&EPA
             United States
             Environmental Protection
             Agency
            Environmental
            Systems Laboratory
            P.O. Box 15027
            Las Vegas NV 89114-5027
EPA-600/4-84-058
June 1984
             Research and Development
Western  Regional
Visibility Monitoring
Teleradiometer and
Camera Network

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                          WESTERN REGIONAL VISIBILITY MONITORING:
                             Teleradiometer and Camera Network
                    John Muir Institute for Environmental  Studies, Inc,
                                     743 Wilson Street
                                  Napa, California  94558
                              Cooperative Agreement #CR808562
                                      Project Officer

                                       Marc Pitchford
                            Advanced Monitoring Systems Division
                        Environmental Monitoring Systems Laboratory
                                      P. 0. Box 15027
                                  Las Vegas, Nevada  89114
 v
 r
                        ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
O                           OFFICE OF RESEARCH AND DEVELOPMENT
O                          U.S. ENVIRONMENTAL PROTECTION AGENCY
                                  LAS VEGAS, NEVADA  89114

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                                    NOTICE

     The information in this document has been  funded  wholly  or  in  part  by  the
United States Environmental  Protection Agency under cooperative  agreement
numbers CR 805788 and CR 808562.   It has been subject  to  the  Agency's  peer  and
administrative review, and it has been approved for publication.  The  contents
reflect the views and policies of the Agency.  Mention of trade  names  or com-
mercial products does not constitute endorsement or recommendation  for use.

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                                   ABSTRACT

     The 1977 Clean Air Act Amendment provides for protection  of visual  air
quality of certain federally managed lands.  In support of these provisions
the U.S. Environmental  Protection Agency, in cooperation with  the National
Park Service, has sponsored a number of visibility research programs.   One
program involves development and operation of a western regional visibility
monitoring network.  The objectives of this network are to develop visibility
monitoring methods, to characterize visibility in this regions,  and to provide
data that can be used to identify sources of visibility impairment.

     This report describes the western network and methods used  to collect and
process data, the results for the period of record and quality assurance pro-
cedures.  A visibility theory section is provided to define terms and  concepts.
Seasonal and monthly mean standard visual range values with 90 percent confi-
dence intervals and cumulative frequency plots for each monitoring location  are
reported.  This report covers the data collection period from  summer of  1978
through fall of 1981.
                                    i n

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                              TABLE OF CONTENTS
                                                                      Page

Abstract	iii
Tables 	    v
Figures	   vi
Introduction 	    1
Visibility Theory  	 ...    2
Measurement Methodology  	    5
     Manual Teleradiometer 	    5
          Instrument Description 	    5
          Operation	   10
          Meteorological and Sun/Snow Codes  	   11
     Camera System 	   12
          Loading film	   12
          Operation	   12
     Quality Assurance  	   12
          Preventive maintenance 	   17
          Functional checks  	   17
          Data quality check	   17
          Documentation  	   17
Network Description  	   22
     Teleradiometer Network  	   22
     Camera Network  	   30
Data Processing	   32
Summary of Results	   34
References	   39
Appendices
     A.  The Spectral Consistency Editing Test 	   40
     B.  Time Plots of Monthly Standard Visual Range 	   42
     C.  Cumulative Frequency Distributions of Standard Visual Range .   71
                                     IV

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                                    TABLES
Number                                                                Page

  1    Meteorological  and Snow Codes Used Before 10-1-80 	  16
  2    Contrast Teleradiometer Maintenance   	  18
  3    Camera Systen Maintenance 	  19
  4    Site/Target Information 	  24
  5    Inherent Spectral  Contrasts as a Function of Vegetation,
       Lighting and Wavelengths  	  29
  6    Camera Network   	  31
  7    Seasonal Mean Standard Visual Range 	  35

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                                   FIGURES
Number                                                                Page

  1    Elements of visibility  	    3
  2    Manual  teleradiometer 	    6
  3    Manual  teleradiometer optics  	    7
  4    Manual  teleradiometer eyepiece reticle  	    9
  5    Meteorological  code instructions used by teleradiometer
          operators	13
  6    Sun/snow code instructions used by teleradiometer operators  .  .   14
  7    Data recording  instructions used by teleradiometer operators  .   15
  8    Optical  alignment target  	   20
  9    Regional visibility monitoring network teleradiometer locations   23
 10    Flow of data from manual teleradiometers to final  graphics   .  .   33
 11    Median  standard visual range (km), summer 1978 through
          fall  1981	38

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                                 INTRODUCTION

     Since the 1950's there has been an increasing concern that the beauty of
many of our nation's natural wonders is threatened by industrial  development
and population growth.  Pollution from such sources as coal-fired powerplants
began to reduce the visual clarity in many of these areas by the 1960's (EPA
1979).  The increasing public concern resulted in specific visibility provi-
sions being included in the Clean Air Act Amendment of 1977 (Public Law 95-95;
August 7, 1977).

     Provisions in the 1977 law deal with preventing of new visibility impair-
ments in federal mandatory Class I areas (international parks, national wilder-
ness areas, and national  memorial parks exceeding 5,000 acres; and national
parks exceeding 6,000 acres) and with remedying existing impairments in sel-
ected National Parks and National Wilderness Areas.  The provisions provide a
system to plan for and manage the use of the remaining air quality resource in
areas of the country where air quality is better than National Secondary
Ambient Air Quality Standards.  In Class I areas safeguards are to be insti-
tuted to assure no air pollution damage to "air quality related values (includ-
ing visibility)."

     Data needs to meet these requirements include information about current
conditions and possible visibility impairment by emissions from particular
sources.  This report describes research designed to assist the U.S. Environ-
mental Protection Agency (EPA) and other federal and state agencies and oper-
ators of possible visibility impairing sources to address potential visibil-
ity problems in an expeditious and orderly way.

     The report describes a western regional visibility monitoring network
established by EPA in cooperation with the National Park Service to character-
ize visibility in representative Class I areas and to provide data that can be
used to identify the sources of visibility impairment.  Description of the
methods used to collect and process the data, the monitoring locations, period
of record, quality assurance procedures, and a descriptive summary of the data
collected are included.  A visibility theory section provides definitions of
concepts and terms.

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                              VISIBILITY THEORY

     This section provides an overview of the physical  processes  which deter-
mine visibility.  It is adapted from the EPA Interim  Guidance  for Visibility
Monitoring (EPA 1980).  Several references are available  for those who wish
to learn more about visibility theory (Middleton  1952;  Malm 1979; Malm 1982;,
EPA 1979; and EPA 1980).

     Visibility can be broadly defined as the degree  of clearness of the  atmos-
phere.  Traditionally, visibility has been defined  in terms of visual range--
the distance from an object that corresponds to a minimum detected or threshold
contrast between that object and its background.  Threshold contrast refers to
the smallest difference between two stimuli  that the  human eye can distinguish.
The measurement of these quantities depends  on the  nature of the  observer, this
or her physical health, and mental  attitudes of attention or distraction  such
as effects of boredom and fatigue.

     Although visibility defined in terms of visual  range is a reasonably pre-
cise definition, visibility is really more than being able to  see a target at
a distance for which the contrast is reduced to the threshold  value.  Visibil-
ity also includes seeing vistas at  shorter distances  and  being able to appre-
ciate the details of line, texture, color, and form.  The definition of visi-
bility and the selection of methods for monitoring  visibility  should relate to
these different aspects of perceiving distant objects.

     The importance of air quality  impact on visibility,  "the  seeing" of  dist-
ant objects, is based on the ability of aerosol and gases to scatter and  absorb
image-forming light as it passes through the atmosphere.  The  loss of image
forming light is proportional to the sum of b  (scattering coefficient) plus
b .   (absorption coefficients).  The combined effects of  scattering and ab-
s8rption are referred to as extinction, represented by  b    (extinction coef-
ficient).  Scattering by the gases  which comprise unpolluted air  is referred
to as Rayleigh scattering.  The Rayleigh scattering coefficient,  bR  ,  .  . , is
dependent on air density.  Figure 1 graphically displays  the various erements
of visibility, which are described  in greater detail  below.

     Radiance, N, is a measure of the amount of monochromatic  radiant energy
present at some point in space.  Thus, .N ,  the apparent  target radiance  inci-
dent at an observation point located a Sistance r from  some target, is a  meas-
ure of radiant energy reaching an observer who is viewing a target in some
specific direction.   N  then is the sum of the attenuated inherent radiance
of the target, .N , and radiant energy scattered by the intervening atmosphere.
The radiant energy scattered by the intervening atmosphere is  a result of air
molecules or aerosols scattering direct sun, diffuse  light, or ground reflected
light into the sight path.  The volume scattering function determines how much
of the radiant energy incident on the sightpath is  scattered toward the eye.
It is a minimum for radiant energy  incident perpendicular to the  sightpath and
a maximum for radiant energy incident on the sight  path in front  of the ob-
server (forward scattering).

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                                                           Background
                                                           Sky
                                                           Target
Figure 1.  Elements of visibility.
                                                            the inherent back'
                                                             and ^N_ respec-
           tively while ,N  and
The observer is at a distance r from the target;
ground and target radiance are represented by  N  and  N

                      N  are the apparent background and target
radiances.  Point (1) represents the reduction of sky and target
radiance resulting from absorption; point (2) shows the reduction
in sky and target radiance resulting from scattering; point (3)
represents the increase in target and sky radiance resulting from
sunlight scattered into the sight path; while point (4) represents
increase in target and sky radiance due to scattering of sky light
and ground reflected light.

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     Apparent target contrast,  C ,  is  defined  as  the  difference between target
radiance, .N , and some background  radiance, .  N   (when  the background is the
sky, .N  becomes  N ), divided  by the  background  radiance.
               Cr =
In a similar manner, inherent contrast,  C  ,  is  defined  to be the contrast of a
target viewed at a distance r=0,  against a background sky:                  ,

               C  = LN  -  N )/  N .                                   (2)
                o   vt o   s o" s o                                   v  '
     The ratio of the apparent to inherent contrast  (C  /C ) is contrast  trans-
mittance, a measure of the ability of an intervening atmosphere to transmit
contrast.  The equation that describes the reduction of contrast over  a  path
of length r is given by:
               Cr = C0WsN

     The quantity  N /  N  is equal  to 1  if  the  earth  is assumed to be flat,
the atmospheric aer"oiof Snd gas concentrations  are  assumed to be evenly dis-
persed both in the vertical and horizontal, and the observation angle is equal
to zero (horizontal sight path).  With these assumptions, equation (3) can be
transformed to an equation for the extinction coefficient, b  .  :

               b    = (_i/r) in(C /CJ.                               (4)
                ext   x          r  o'                               x  '
In addition, if the above assumptions are met,  visual  range can be calculated
from the extinction coefficient by:

               Vp = 3.912/bext.                                      (5)

     To account for the effect of air density at different elevations, we
define standard visual  range as:

               cu  _ _ 3.912 _ ,                              (6)
                 r~bext-bRayleigh+0-01

where the 0.01 is the reference Rayleigh scattering coefficient (km~  ) corres-
ponding to a reference altitude of 1.55 km  above sea  level.

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                           MEASUREMENT METHODOLOGY

     A contrast measurement technique, using teleradiometers,  was  chosen  to
measure visibility.  These instruments measure the amount  of  radiant  energy
reaching a detector from selected viewing targets  and  their surrounding back-
ground.  Teleradiometers directly measure the apparent spectral  radiance  of
the sky, target or a plume and thus allow for a calculation of target or  plume
contrast and its change.  The apparent contrast of targets (or plumes) can be
easily calculated from the measurements using equation 1  or 3.   Visual range
can also be calculated after making a series of assumptions about  the inherent
contrast of the target, uniformity of the atmosphere along the sight  path, and
angle of observation.

     Teleradiometers make measurements in a  way that is very  similar  to obser-
vations made by the human eye.  In Figure 1, the eye could be  replaced by a
teleradiometer.  Properties of the target, air quality (homogeneity and concen-
tration of visibility reducing substances),  distance to the target, illumina-
tion of the sight path, humidity, and observation  angle all affect the measure-
ment.

     Photography was also employed at many of the  network  sites  to provide a
means to qualitatively document changing visual air quality on various vistas.
This is particularly important where plumes  or layered haze are  a  concern
since the teleradiometer would not necessarily provide a  measure of these con-
ditions.

MANUAL TELERADIOMETER

     The manual teleradiometer consists of a 0.5-meter focal  length objective
lens, filter turret, beam diverter, flip mirror, eye piece, photodiode, and an
electrical system consisting of batteries, switches, a liquid  crystal display,
and various electronic components.  The photodiode provides the  interface
between the optical and electrical systems by producing an electrical current
proportional to the amount of radiant energy which strikes its surface.   The
unit is portable (weighing 3.2 kilograms), battery powered, and  manually  oper-
ated.  A tripod or more permanent mounting device  is required  to steady the
teleradiometer during measurements.  The teleradiometer has been designed for
ease of operation and can be readily dismantled.  Figure 2 shows a manual tele-
radiometer, and Figure 3 is a diagram of the associated optical  system.   A
brief discussion of the various system components  is given below,  followed by
a discussion of the operation of the instrument.

Instrument Description

     The telescope lens has a nominal diameter of  54 mm with  a clear  aperture
of 47.5 mm and a focal length of 508 mm.  The lens is  a cemented and  coated
achromat.  The lens can be removed easily for cleaning and can be  adjusted to
focus the target image.  The filters are mounted in a  five-position filter

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                                                               VistaRanger1
                                                                On/Off Switch





                                                   Ratio/Direct Switch





                                  Battery Condition Indicator




                                        Display




                       Vertical Vernier




                  Eyepiece.
      Filter Turret
Focus
                                                      Battery Cover Fastener(2)




                                            Battery Condition Switch




                                  Flip Mirror Knob




                         Sky/Target Knob
       Figure 2.   Manual Teleradiometer.

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     Telescope
     Objective
        Lens
                                      Eyepiece
                                                                       Photodiode
                                        Beam
                                       Diverter
 Flip
Mirror
                        Filter
                       Turret
Figure 3.  Manual  Teleradioneter Optics  (based on Model  3010 VistaRanqer"
           Optics).                                                     H

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turret and correspond to wavelengths of 405,  450,  550,  and  630 run.   One  filter,
centered in the green (550 nm), is coincident with the  wavelength of maximum
response for the human eye.  The turret is also fitted  with a  clear  glass  piece
which is used to align the instrument on the  target.   The filter turret  is
located between the telescope lens barrel  and the  main  instrument assembly  and
is held stationary by two hex screws (see Figure 2).   The turret can be  removed
easily by the operator for routine cleaning of the filters, or, if necessary,
for repairs.

     The beam diverter is a disk of clear acrylic  which, when  rotated  from  the
sky to target position, causes the target image to be displaced (in  the  ver-
tical direction) by 3.0 mm.  This makes it possible for the single photodiode
to measure both the sky and target apparent spectral  radiance  without  moving
the instrument (see Figure 3).  A manually operated flip mirror allows the
operator to direct the target image to either the  eyepiece  for viewing,  or  to
the photodiode for measurements.  A knob on a threaded  screw is provided to
allow a fine adjustment of the instrument elevation angle.   While the  tripod
is used for coarse adjustment of the azimuth  and elevation  angles, this  screw
adjustment provides a fine control for the elevation  setting and aids  in sight-
ing the target.

     The eyepiece has a reticle to aid in the alignment of  the teleradiometer.
A horizontal horizon line in the middle of the field  of view is typically
placed on the peak of the target of interest.  There  is a small circle above
the line and another directly below it on the other side of the line,  with
identical distance between each circle and the line.   The circles show the
portion of the view to be focused on the photodiode when the beam diverter  is
turned to sky or target position.  The eyepiece is also provided with  a  lens
cap in order to prevent stray light from hitting the  photodiode.  Stray  light
will  affect the readings by decreasing the apparent contrast and visual  range.
Figure 4 shows an illustration of the eyepiece reticle. The photodetector  is
a single, blue-enhanced, PIN silicon photodiode.

     A key component in the teleradiometer is the  analog to digital  converter
with a 2 volt liquid crystal display (LCD).  This  display reads out  voltage in
millivolts up to a maximum of 1999.  Though the display has four place preci-
sion, the rightmost digit is rounded off by the operator so that the recorded
numbers do not misrepresent the precision actually achievable  by the teleradi-
ometer.

     As with most battery operated instruments, insufficient battery voltage
is the most common cause of failure.  Early model  teleradiometers are  equipped
with three 9-volt alkaline batteries.  One battery supplies the very low power
needed by the LCD while the other two operate the  main  circuitry.  The latter
two batteries must each have at least 7.0 volts for proper  operation of  the
teleradiometer.  For this reason, each instrument  has been  equipped  with a
battery test circuit incorporating a light emitting diode (LED) and  a  test
switch.  Upon activating the switch, the LED will  light only if the  battery
voltage exceeds 7.0 volts.  In newer models the LED test circuit has been  elim-
inated.  When the battery voltage drops below 7.0  volts, a  low battery signal
is displayed on the LCD.

                                     8

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                                                               .31mm Dia.
                                                                .31mm Dia.
Figure 4.   Manual  Teleradioneter  Eyepiece  Reticle  (Model 3010 VistaRanger"),

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     The instrument has an on/off switch,  a Direct (D)/Ratio (R)  switch,  and,
in older models, a battery test switch.   In the direct mode, the  LCD will  dis-
play a voltage proportional to either the  sky or target apparent  spectral  radi-
ance.  In the ratio mode, the LCD will  display a voltage proportional  to  the
ratio of target to sky apparent spectral  radiance.

Operation

     The procedure used to riake contrast  measurements  with  the  manual  teleradi-
ometer consists of five steps:  set up,  target sighting, measurement,  data
recording and a recheck of target sighting.

     The teleradiometer is positioned in  the same location  for  each series  of
measurements.  The instrument is switched  on and allowed to warm  up for a  brief
period of time.  The battery integrity is  checked prior to  the  measurement
process.

     The reticle in the eyepiece aids aiming by providing a horizon line,  a
small target circle beneath it and a small  sky circle  directly  above it  (see
Figure 4).  The observer usually puts the  horizon line on the peak of  the
mountain and the target circle on the target area.  The target  is usually
chosen to be a patch of coniferous trees  so it will  be green throughout the
year.  The horizon line need not be exactly on the top of the mountain peak.
The important requirement is that the sky  circle must  be completely filled
with sky when the target circle is completely filled with target. The aiming
procedure is done with the beam diverter  knob in the sky position and  the  fil-
ter turret set on C (clear glass).  Small  adjustments  in the azimuth and  ele-
vation angles are made to put the target  circle on the particular patch of
trees with the least amount of rocks appearing between the  trees. A vernier
adjustment has been provided to aid in the elevation adjustment.

     If necessary, the instrument is focused by loosening the lens adjusting
screw, sliding the lens in or out until  the image focuses,  and  then tightening
the adjusting screw.

     The instrument is designed to make  the fewest possible measurements  neces-
sary to compute visibility related variables.  In ratio mode, the electronics
are designed to measure and store the apparent spectral radiance  of the  sky as
a voltage and divide it into the target  apparent spectral radiance.  The  output
to the liquid crystal  display is the ratio.  After reading  the  ratio,  the
apparent spectral radiance of the target  is measured.   This is  done by switch-
ing the Ratio/Direct switch to Direct.

     A final check to ensure that the teleradiometer is still properly aligned
on the target is done immediately after  taking the measurements.   This is  done
by rotating the filter turret to C (clear  glass) with  the beam  diverter  in  the
sky position and viewing the target through the eyepiece.  If the target  circle
(Figure 4) is not on the target, then the  teleradiometer is realigned  and  the
measurements repeated.


                                     10

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     A data sheet is used to record every  measurement.   Each  data  sheet  is
identified by a unique location code,  month and  day.   The  operators  are  encour-
aged to write notes on the record sheet,  indicating  any  problems or  special
observations.  In addition to the ratio and target direct  readings,  meteorol-
ogy, sun and snow codes are recorded for each  target.

Meteorological  and Sun/Snow Codes

     The view of a distant target depends  on the contrast  of  the target  against
its surroundings.  The contrast depends on the light  reflecting characteris-
tics of the target, the illumination of the target and the sight path, and
the optical characteristics of the air along the sight path.   To help  specify
these conditions, a meteorological  code and sun/snow was assigned  to each tar-
get for each measurement.  The codes are included on  the data sheet.

     The meteorological code serves two functions.   It describes the cloudiness
of the sight path, and it describes certain situations when measurements are
not made.  Meteorological code 0 denotes a cloud-free sky, which provides the
simplest illumination of the target and atmosphere.   Meteorological  code 1
denotes a cloud-free observation plane defined by the target, observer,  and
sun.  This case is still relatively simple optically, because there  are  no
clouds in the plane that can cause non-uniform illumination of the sight path
or target.  Clouds can be present elsewhere in the sky for this code but they
have less effect on the illumination of the sightpath.   Meteorological codes
2, 3, and 4 denote some clouds in the observation plane.  Code 2 is  for  clouds
covering up to one-third of the sky; code  3 is for one-third  to two-thirds
cloud cover; and code 4 is for more than two-thirds  cover. Meteorological
code 5 is for a completely overcast sky.   Readings recorded for meteorological
codes 0 through 5 can be analyzed for various  amounts of clouds.

     Higher numbers of the code do not have accompanying readings.  Code 6
means it was raining on the teleradiometer site. The observers are  instructed
not to take readings in the rain, a precaution that  helps  protect  the  telerad-
iometers from water damage.  Code 7 means  the  readings were not taken  because
of some reason not related to the atmosphere.   For example, the observer may
have been called to help in an emergency.   If  measurements cannot  be taken due
to the sun shining into the lens, then the observer  records code 8.   If  sun-
light directly strikes the lens, then the refracted  light  may strike the photo-
diode and change the reading.  Operators may fabricate an  extension  for  the
sunshade on the teleradiometer in order to make  an otherwise  disallowed  read-
ing.

     Each meteorological code is paired with a sun/snow  code.  The sun/snow
code describes the relative amount of snow on  the target and  the lighting con-
ditions on the target at the time of the measurements.   Snow  greatly increases
the reflectance of light from the target towards the observer and  from the
ground to the sight path.  While the meteorological  code describes the condi-
tions relative to the entire sky, the sun/snow code  describes conditions rela-
tive to the individual targets.  In most cases,  the  meteorological code  will
be the same for all targets, whereas the sun/snow code will probably vary.   It
should be noted that an important variation on the situation  exists  when the
target cannot be seen.  If it is obscured  by air pollution rather  than clouds,


                                     11

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then the regular meteorological  code should be recorded as determined  by cloud
cover.  Instead of regular readings though, -1 is recorded for each of the
four ratios and each of the four target radiances.

     The meteorological and sun/snow codes are summarized  in Figures 5 and 6.
Figure 7 summarizes the measurement and data recording process using a flow
diagram.  By following the logic shown in the diagram, the proper codes can be
accurately assigned to the data.  Prior to October  1,  1980, a similar  though
less complex code system was used (see Table 1).

CAMERA SYSTEM

     In order to photo document vista appearance and weather conditions, color
photographs were taken of selected targets.  The photographs were taken twice
a day during the morning and afternoon manual  teleradiometer measurements.

     The Olympus OM-2 35-mm SLR automatic camera, equipped with a 135-mm tele-
photo lens and a haze filter, is used in the network.   Kodachrome ASA  25 color
slide film is used at all locations for consistency.  This film was chosen
because it was reputed to give the best representation of  true color.

Loading Film

     A fresh roll of film is loaded into the camera following the manufactur-
er's instructions.  The roll number, date and location are recorded on a log
sheet.  The automatic flash is installed and the camera is set on auto mode.
A gray scale and color chart are photographed.

Operation

     The camera is set on automatic with an aperature  setting of f/4.   For
most daylight conditions, this setting produces a good photograph.  The camera
automatically adjusts the shutter speed.  If the camera is equipped with a
data back, the date and time display are checked and adjusted if necessary.
The target is sighted through the viewfinder.  For  most targets, the focus
setting will be infinity.  The photograph is taken  and the exposure, date,
time, target number and/or name and any notes or comments  about the photo-
graph are recorded on the log sheet.

QUALITY ASSURANCE

     To prevent loss of valuable data due to instrument malfunction or "out of
control situations," a strong quality control  effort is necessary.  The quality
control program consists of four tasks:

     1.   regular preventive maintenance and operational  checks;

     2.   frequent functional checks of all instrumentation;

     3.   data quality checks; and

     4.   documentation


                                     12

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                                         MbTEDROLOGICAL COOES
                          Code    Condition
                            0      Total sky cloudless
                            1      No clouds in  sun-target-observer  plane
                            2      Less than 1/3 cloud cover,  total  sky
                            3      1/3 to 2/3 cloud  cover,  total  sky
                            4      2/3 to total  cloud cover
                            5      Overcast
                            6      Raining on site
                            7      Readings not  taken - unrelated to
                                   atmospheric  conditions
                                  Sun in lens,  readings not taken
           MET CODES
            Code 0
                ttiis code is fairly obvious.  Ihe only problem may occur when
                there are very faint high wispy clouds. As  in all cases, use
                your own discretion.
            Code 1
                Itiis code often causes problems.   If the net code for most of
                your targets is a 2, 3, or 4, that is there are clouds in the
                sky, it is still possible to have a target with no clouds in
                the target-sun-observer plane, ttiat target would receive a 1.
           Code 2, 3, 4
                These codes are not to be used independently for each target
                because of the total sky concept.   If less than 1/3 of the
                total sky is covered, then the met code is the same for all
                targets.  Two exceptions to this are:

                     Code 1 - even though 1/3 of the sky is covered, this
                     particular target has no clouds in tlie target-sun-
                     observer plane.

                     Sun/snow code 9 - target obscured by clouds, met code
                     remains the same, sun/snow code becomes 9.

           Code 5

                Overcast; total sky is cloud covered.

           Code 6

                Raining on the observation site, readings not taken.

           Code 7

                Readings not taken for reason not  relating to the atmosphere.  It
                helps to write the reason down that day, as it is often hard to
                remember later.
           Code 8
                If you are unsure about sun hitting the front lens, set the telephotometor
                to take a direct reading of the target, then shade the end of the teiescoie
                with your hand.   If the direct reading drops appreciably, then this
                target should receive a code  8, or the telephotcnetcr should be fitted
                with a sun shade.
Figure  5.   Meteorological  code  instructions used  by teleradiometer operators.
                                                13

-------
TARGET
IN SUN
US
YES
YES
YES
NO
NO
NO
NO
CLOUD
BEHIND TARGET
YES
YES
NO
NO
YES
YES
NO
NO
SNOW ON
TARGET
YES
NO
YES
NO
YES
NO
YES
NO
                                       SUN/SNOW CODE
                          pnpE

                           1
                           2
                           3
                           4
                           5
                           6
                           7
                           8
                           9      Target obscured by clouds


          This code is most useful in data interpretation for close or intermediate
          targets.  For these, you should be able to make accurate estimates.


               1.  Make determinations of these codes by utilizing both direct
                   and telephotoneter observation.

               2.  The area of the target within and around the detector circle
                   should be considered.  If most of the mountain is in the sun
                   but the detector circle is in shade, then the target would
                   be considered to be in the shade.  If there are no clouds
                   behind most of the mountain, but there is a cloud in the
                   detector area, then the target is considered to have a cloud
                   background.

               3.  If there happens to be a large snow bank or shade patch that
                   is half in your detector area, feel free to move the detector
                   slightly to an area of more uniform density.  This also stops
                   very jumpy readings caused when the detector alternately hits
                   light and dark patches due to wind.

               4.  When using the sun/snow codes, don't worry about being mis-
                   taken on very distant targets.  If you are in doubt about
                   whether the target is in the sun or shade, and it's hard to
                   estimate from the cloud cover, assume that the target is in
                   the sun.
                   If in doubt about whether or not there are clouds behind the
                   target,  assume there are no clouds.

               5.  In distinguishing between a partially snow covered and a
                   covered classification, an estimate must be made as to the
                   dominant effect on reflected light.  A new snow on the target
                   would obviously warrant a covered classification.  There comes
                   a time,  however, when the trees and shrubs become more dominant
                   in the view.  Once again it is a subjective judgement and you
                   can only do your best.
Figure  6.   Sun/snow code  instructions  used by teleradiometer  operators,
                                                14

-------
                                                  Telephotometer Data  Recording Instructions
                                                                          Start Here
                   Not taken because of
                   weather conditions?
                                      No
                        Yes
                   Precipitating on the
                   observation site?
                                         No
                        Yes
                        TeS
                    Record:
                    met. code = 6
                    leave readings blank
                                                  No
                     Are you going to take
                     a measurement?
Instrument broken, illness,
emergency or other reason
unrelated to the atmosphere?
                                                            Yes
                                                   Record:
                                                   met. code = 7
                                                   leave readings blank
 Target totally obscured
 by distant rain or clouds?
                                                          Ye,
                                                          Yes
  Record:
  met. code = 8
  leave readings blank
                                                                                                      Yes
                                                                                                        No
Target not seen due
to poor air quality?
                                                                                            Is display on instrument blank.
                                                                                            or blank with 1 on the left?
                                                                                                     No
                                                                            Does reading meet
                                                                            the following criteria?
                                                                             U or B  < 99
                                                                                  G  < 98
                                                                                  R  <98
                                                                             (means less than)
                                                                                                                                    Yes
                                                                             Record two or three
                                                                             digit number after
                                                                             rounding right most
                                                                                                                             Take direct readi
                                                                                           ng]
                                                                                                                                   Yes
                                                                                            Record two or three
                                                                                            digit number after
                                                                                            rounding right most digit.
                                                                                                                      Leave direct reading blank]
Figure  7.   Data recording instructions  used  by  teleradiomater  operators,

-------
TABLE 1.  METEOROLOGICAL AND SNOW CODES (used before 10-1-80)
Meteorological
     Code

       0
       1
       2
       3
       4
       5

Snow Code

       1
       2
       3
       4
       5
       6
          Condition

Cloudless sky
No clouds in plane of sun, target and observer
Total  sky is less than 1/3 cloud covered
Total  sky is 1/3 to 2/3 cloud covered
Total  sky is more than 2/3 cloud covered
Overcast sky

          Condition

No snow on target; no snow on ground
Covered target; covered ground
Covered target; partially covered ground
Covered target; no snow on ground
Partially covered target; any condition on ground
No snow on target; any condition on ground
                                     16

-------
Preventive Maintenance

     Tables 2 and 3 summarize the various types of maintenance which  are  per-
formed.  Most of the tasks are done on a weekly basis,  although some  items  are
done only as needed.

Functional Checks

     Functional  checks are performed less frequently than the preventive  main-
tenance tasks.  The checks discussed in this section are performed  monthly.

     The photodetector must be aligned with the optical  system so that only
light from the target area is measured.  The detector must be aligned in  both
the horizontal and vertical planes; otherwise, it will  respond to light re-
ceived from some area in the field of view other than the desired target  area.
The optical alignment check is designed to verify that the target as  viewed
through the eyepiece is the same as that seen by the photodetector.

     The optical alignment check is performed using a target consisting of  a
black background with a white dot and two white lines or stripes, one hori-
zontal and one vertical, and each approximately 1 cm across.  On the  opposite
side are two white lines forming crosshairs.  Figure 8 shows a simple diagram
of the optical alignment target.  Basically the test consists of horizontal
and vertical scanning of the alignment target with the teleradiometer in  an
effort to find the orientation with greatest signal.  That orientation should
correspond to a white portion of the target aligned with the proper eyepiece
reticle.

Data Quality Check

     The data sheets are reviewed for errors by field personnel.  The sheets
are checked to ensure that:

     1.   the meteorological and sun/snow codes have been assigned  to each
          target correctly;

     2.   the contrast readings have been entered on the data sheet correctly,
          e.g., all two-digit values have been entered right-justified;

     3.   the data sheets contain the location, date, and operator's  initials;

     4.   any missing data are accounted for either through the appropriate
          meteorological code or a notation by the operator indicating why
          the readings were not taken; and

     5.   the readings are consistent.  Experience will  indicate when certain
          values seem inconsistent with past readings for a given target.

Documentation

     Results of all preventive maintenance tasks, functional checks,  or any-
thing that could affect data quality are documented.  Standard procedures for


                                     17

-------
TABLE 2.  CONTRAST TELERADIOMETER MAINTENANCE
Item
  Maintenance Action
Examine  Clean  Replace
Frequency
Remarks
Batteries
                           Before each series  Check voltage; if
                           of measurements     less than 7.0 volts,
                                               replace.
Optics (lens,   x
  filters,
  etc.)
Mount (tripod)  x
                           Once per quarter

                           Once per week




                           As requi red
               Use soft tissue.
               _D_ not use concen-
               trated solvents or
               abrasives.

               Tighten all  screws,
               nuts, etc. Lubri-
               cate necessary parts.
                                     18

-------
TABLE 3.  CAMERA SYSTEM MAINTENANCE
Item
  Maintenance Action
Examine  Clean  Replace
Frequency
Remarks
Lens
Batteries
  light
  meter
Auto winder*
Tripod*
Timer*
                           Once per week



                           Once per week


                           As required


                           Once per week

                           As required


                           Once per week

                           As required


                           Once per week
               Lens should be in-
               spected for chips,
               tightness, etc.

               Battery voltage
               should be checked
               using either exter-
               nal  voltmeter or
               internal  check.

               Operator should
               check battery volt-
               age  at least once
               per  week.

               Camera mount should
               be checked to verify
               that all  parts are
               tight.

               Timer connections to
               data recording sys-
               tem  and camera must
               be securely fastened.
* For sites with automated camera systems.
                                     19

-------
               Front
                 O
              Back
               IL
Figure 8.  Optical alignment target.
                 20

-------
equipment operation, maintenance, quality control  and data handling are docu-
mented in a procedures manual.  The data are maintained on original data
sheets, computer cards and magnetic tapes.  Data are periodically reproduced
with copies stored in different locations to reduce the chance of loss by
damage to the principal data library.
                                     21

-------
                             NETWORK DESCRIPTION

TELERADIOMETER NETWORK

     Manually operated teleradiometers were installed  in  16 National  Park
Service Class I areas, 10 sites of mandatory Class  II  status (national  monu-
ments, national primitive areas, national  preserves, national  recreation  areas,
national  wild and scenic rivers, national  wildlife  refuges, or national  lake-
shores or seashores of 10,000 or more acres) and two sites  at  Lake  Tahoe  that
adjoin National Forest Service Class I areas.  Figure  9 shows  the western
regional  observation site locations (excluding Olympic, WA, Shenandoah,  VA,
and Acadia, ME).  The monitoring has been  continuous since  its initiation.
For most  sites, monitoring began in the summer of 1978.  At all  but one  site,
measurements were made three times daily at 9 a.m.,  12 noon, and 3  p.m.  local
time.  The 12 noon measurement was not performed at  Chaco Canyon.

     The  observation site at each park or  monument  was chosen  to provide  a
variety of vistas toward distant targets.   Up to six targets in  a variety of
directions were selected at each observation site.   The targets  were selected,
where possible, at distances between 10 and 75 percent of the  estimated  average
visual range, as recommended in the Interim Guidance for  Visibility Monitoring
(EPA 1980).  Within these distances, apparent contrast is most sensitive  to
changes in airborne fine particulate concentration  (Malm  1979).

     To provide a more reliable data base, desirable target characteristics
included  a distinctive shape for easy aiming of the teleradiometer  at  the tar-
get, a low elevation angle of observation, and a dense cover of  evergreen vege-
tation.  However, rock targets were also selected to provide a greater variety
of situations for future investigations of apparent  color changes with visi-
bility degradation.  Table 4 lists the specifications  for each target.  As
seen in Table 4, some target changes were  made at Grand Canyon and  Bryce
Canyon National Parks.

     The  computation of standard visual range requires knowledge of the
inherent  spectral contrast, C  of the targets.  This was  measured in a series
of field  experiments, using different vegetation types under varying illumin-
ation.  The measured inherent spectral contrasts shown in Table  5 were used to
determine the proper values for each target at each  of the  three times of day.
These measurements indicated that evergreen vegetation was  a satisfactorily
dark target in direct sun or shade, but rock targets in direct sun  had varying
and unpredictable inherent spectral contrasts.  Therefore,  computations  requir-
ing C  were not made for rock targets.  Similarly,  targets  covered  with  decid-
uous vegetation were not used in autumn and winter  when the leaves  change
color.  The direction to the target from the measurement  location was  used to
estimate  the direction of sunlight on the  target and the  inherent spectral
contrast  of each target at each measurement time.
                                     22

-------
             0
Station number
Figure 9.  Regional  visibility monitoring network teleradiometer locations.
                                     23

-------
                                                                         TABLE 4.   SITE/TARGET INFORMATION
ro
Location
Number Location Hane
1 Canyonlands national Park





2 Grand Canyon National Park



(before in Hay 1979)
(after 9 Hay 1979)

3 Canyonlands National Park





4 Rryce Canyon National Park


(after 9 June 1979)


S Capitol Reef National Park

.



6 Dinosaur National Honunent





Target
Number Hane

1
2
3
4
5

1
2
3
4
4
5

1
2
3
4
S

1
2
3
4
5

1
2
3
4
5

1
2
3
4
5
Island In the Sky
South Mountain
Patmos Mountain
Old Woman Plateau
Thousand L. Mountain
lit. Ellen
Hopl Fire Tower
Shiva Saddle
Trumbull Mountain
Red Rutte
Hunphrey
Kendrlck
Desert View Point
Hans Flat
Ht. Holmes
Mt. Ellen Flank
San Rafael Swell
Book Cliffs
Abajos
Bryce Point
Navajo Mountain
Table Cliffs
Table Cliffs Plateau
Parker Mountain
Cottonwood Peak
Panorana Point
Capitol Gorge
Ht. Pennell
Ant H111
Teasdale Bench
Repeater Hill
Scenic Overlook
U1nts. (IT
Rook Cliffs. IIT
Rabbit Mountain, CO
Book CHffs. CO
Cathedral Bluffs, CO
Lat
(tl)
3R27'
3B23'
3R41'
3R-41'
3825'
3ft7'
364'
36ir
3624'
35-50'
35-21'
3524'
363'
3R19'
37-48'
3R10'
3R-38'
3907'
37-51'
3736'
3703'
37-40'
37-42'
38-14'
3756 '
31-iR1
3R-07'
375R'
3fl21 '
3R19'
3R17'
40-17'
40-33'
39-/I1'
3953'
39-36'
4n08'
Long Distance
(-H) (km)
10945'
10P16'
11002'
110-38'
lll-Zfl1
1104R'
112101
U2R'
113-7'
112-6'
11141'
1H053'
m-sr
no-ir
110-35'
110-4H'
11043'
11003'
10930'
11210'
11054'
111541
111054I
U1055'
11239'
111-20'
111-11'
1104R'
11129'
111029.5'
11130.5'
109-00'
110-24'
110-25'
10R-59'
ion5R'
10R-32'
0
50
76
141
144
94
0
16
9fi
2R
91
76.5
30
0
62
57
67
RR
72
0
130
26
27
67
57
0
19
60
17
17
19.5
0
150
141
45
76
42
Azimuth
Angle
n
...
105
345
292
270
246
...
6
293
170
151
163
96
	
215
261
322
8
130

120
76
6R
20
311
	
146
130
283
275
263
	
2R3
24/
1R6
180
132
Elevation
(feet)
5,940
9,600
6,200
8,600
9,900
10,600
7,090
7,750
8,030
7,324
11,790
9.685
7,470
6.500
7,600
8,000
6,500
6,000
10,000
8.300
9.100
10,000
10,000
9,400
7,600
fi.170
6,500
10.100
8,700
7,000
R.260
6,790
11,100
8,000
7,000
7.500
fl.OOO
Elevation
Angle ()
....
1.3
0.06
0.33
0.4R
0.87
...
0.72
0.17
0.02
0.90
0.59
0.22
	
0.31
0.46
0.00
-0.10
0.85
	
0.11
1.14
1.10
0.29
-0.21
	
0.30
1.14
2.60
1.7R
1.R7
	
, 0.50
0.15
0.08
0.16
0.50
Calculate
Target Cover SVr
...
vegetation
1/2 rock
rock and pJD
vegetation
vegetation
...
vegetation
7/8 vegetatlon(pj)
vegetation
dark rock
vegetation
vegetation, rock
...
1/4 vegetation
1/2 vegetation
rocks
pink rock
vegetation
	
vegetation
rock
vegetation
vegetation
vegetation
	
red rock
sub alpine, fir
PJ
rock
3/4 pj
	
vegetation
colored
vegetation
vegetation
vegetation

yes
no
no
yes
yes

yes
yes
yes
yes
yes
yes

yes
yes
no
no
yes

yes
no
yes
yes
yes

no
yes
yes
no
yes

yes
no
yes
yes
yes
            *  - SVr   standard visual  range
            b  - pj " pinion juniper
                                                                                                                                                       (continued)

-------
                                                                            TABLE  1.   (Continued)
rv>
tn
Location Target
(lumber Location (lame Number (lane
7 Mesa Verde National Park





8 Olympic National Park





9 Uupatkl National Monunent





10 Navajo National Monument






 11 Chaco Canyon National
Monunent





12 Randeller National Monunent






1
2
3
4
5

1
2
3
4
5

1
2
3
4
5

1

2
3
4
5

1
2
3
4
5
6

1
2
3
4
5
Far View Visitor Ctr.
Lukuchukal (Its 1
Lukuchukal Mts 2
Hogback
Chaco River Rise
Bridge Timber Mt.
Scenic Turnout
Sequin H111
Mt. Baker Flank
Parllnent Hill
Empress Mountain
Gowlland Range0
Vis. Ctr. Clnrferhlll
White Horse 111 11s
Flank of Humphrey
Top of Humphrey
No Hane Crater
Montezumas Chair
Water Tower
Navajo Mountain

Square Rutte
Black Mesa 1
Black Mesa 2
Tsegl Canyon Vlall
Pueblo Alta Ruins
Beautiful Mountain
Washington Pass
Small Rutte
Hosta Rutte
Mt. Taylor
Naclnlento Mountains
Rln Fire Tower
Cabal lo Mountain 1
Cabal lo Mountain 2
Tecolote Peak
Sanrila Mts. East Peak
Thompson Peak
Lat
(N)
3716'
3fi2R '
3612'
36-38'
36-40'
37in'
4P01'
48-0?'
48-43'
4840V
4R-27'
4R3n'
3530'
3524'
35-22'
35-21'
35-20'
3527'
36-41'
36-02'

3637'
3624'
3640'
3fi43'
36-04'
3628'
36-06'
35-41'
35-37'
35-14'
36-05'
35-47'
35-57'
3557'
35-14'
35-12'
3541'
Long Distance
(-U) (kp)
lOR-291
I09on'
10B-52'
10R-341
10R-29'
108-57'
123-73'
123-06'
122-04'
122-49'
123-39'
1,?330-
111-20'
111-42'
111-38'
111-41'
111017'
11030'
11033'
110-52'

110-57'
Iin848'
110-22'
110-28.5'
107-57'
ion-no-
100-5.?'
108-15'
108-12'
107-35'
Olfi052'
10fi16'
106-20.5'
10fi21'
106-22'
106-20.5'
105-49'
0
106
130
70
109
47
0
19
118
03
53
52
0
34
33
34
21
79
0
48

36
40
16
3.3
0
105
14
54
50
97
09
0
21
21
65
66
45
Aztnuth
Angle
()
...
220
194
185
178
100
	
88
52
29
336
357
	
247
239
236
158
96
..-
325

260
217
96
66
	
297
270
210
202
162
90
	
336
334
190
187
107
Elevation
(feet)
8.000
8,500
9,000
6,060
7,200
8,400
2,050
2,450
4,500
2,300
2,100
1.350
5.220
8.800
10,600
12.350
6.380
3,940
7.350
9,000

7.800
6,800
8.000
7.700
6.430
9,400
8.700
7.970
8.600
11.400
10,200
6,560
9,300
9,300
8,200
7,200
10,100
Elevation
Angle ()
....
0.08
0.14
-0.48
-0.13
0.14
	
0.37
0.36
0.05
0.02
-0.10
	
1.84
2.84
3.66
0.96
-0.28
	
0.60

0.22
-0.24
0.71
1.85
	
0.49
0.4?
0.50
0.76
0.89
0.66
	
2.32
2.32
0.44
0.17
1.39
Target Cover

1/2 - 3/4 pj
1/2 PJ
rock
3/4 vegetation
vegetation
...
pines
pines
pines
pines
pines
...
vegetation
vegetation
vegetation
1/3 vegetation
rock
...
1/2 limestone and
vegetation
all red rock
PJ
PJ
pinion, juniper
	
vegetation
vegetation
1/2 vegetation
1/2 vegetation
vegetation
vegetation
	
grassy
forest
vegetation
vegetation
vegetation
Calculate
svr

yes
yes
no
no
yes

yes
yes
yes
yes
no

yes
yes
yes
no
no

yes

no
yes
yes
no

yes
yes
no
no
yes
yes

no
yes
yes
yes
yes
                                                                                                                                                    (continued)
        cr.ead
-------
                                                                            TABLE 4.  (Continued)
ro
location Target
Nunber Location Name Nunber Nane
13 White Sands National
Monument 1
2
3
4
5
14 Carlsbad National Park
1

2
3
IS Big Bend national Park
1
2
3
4
5
16 Theodore Roosevelt
national Memorial Park 1
(south unit) 2
17 Wind Caves National Park
1
2
3
4
5

ID Colorado National Monunent
1
2
3
4
5
Entrance Station
95 degrees
Flank of Sierra Rlanca
Capitol Peak
The Nose
Rattlesnake Ridge
Tennis Courts
East Rln near Hunter
Park
Colored
Limestone H111
Maintenance Yard
Sierra Del Carmen Hts.
Cabal lo Huerto
Dagger Mountain
Roslllo Mountains
Nine Point Mesa
Scenic Viewpoint
Bullion Rutte
Sentinel Rutte
Ridge
Rank In Ridge
Cicero Peak
Alabaugh Ridge
Horseshoe Rend
Buffalo Gap

Canpground-Plcntc Area
Margarets Mt.
Lookout Mountain
Horse P.ldge
Grand Mesa North
Grand Mesa South
Lat
(N)
2920'
2<)o12.
292fl'
29-33'
2930'
2939'
32-10'
3157.5'

31-56.5'
31-53'
2
-------
                                                                               TABLE 4.   (Continued)
IV
Location
Nunber Location (lane
19 Rocky Mt. National Park





21 Chlrlcahua National
Monument




22 Grand Tetons National Park





23 Shenandoah National Park





24 Capulln Mountain National
Monument




28 Death Valley National
Monument





Target
(lumber (lane

1
2
3
4
5

1
2
3
4
5

1
2
3
4
5

1
2
3
4
5

1
2
3
4
5


1
2
3
4
5
Headquarters
Plerson Mt.
Estes Cone
Longs Peak
Notchtop Mt.
Tombstone Ridge
Hassal Point
Dos Cabezas
Cochlse Stronghold
Potter Peak
Hatchet Mt.
Steins Peak
Windy Point
Snow King
Indian Peak
Phillips Ridge
Huckleberry Ridge
Coulter Peak
Loft. Mt. Campground
Appalachian Mt. Ridge
Massanutten Pt.
Rocky Mt.
Grindstone
High Top
Scenic View
Little Crater( Nameless)
Taos Ridge
Mil low Canyon Ridge
Barilla Mesa
Hater-vale Mesa
Water-Tank Furnace
Creek
Sylvanla Mts.
Tuckl Hash Peak
Owl 's Head Mountains
Golden Canyon
Grapevine Mountains
Lat
(N)
40-22'
40-17.5'
4017'
4015'
4019'
4022'
32-00'
32i3'
3155'
31-31'
31-37'
32-20'
43-40'
46-28'
43-20'
4344'
4344'
435fi'
38-15'
38-35'
3R-23'
38-19'
3828'
38-20'
3fi47'
3635'
3636'
3648'
37-00'
36-58'
36-30.5'

37'22'
3627.5'
35"46'
3625'
3646'
Azlnuth
Long Distance Angle Elevation Elevation
(ll) (kn) () (feet) Angle ()
105-33'
105-28'
105-34'
105-36.5'
105-42'
105-40'
109-20'
109-37'
10958'
109-57'
10R-25'
109-5'
110-43'
110-41'
110-56'
110-52'
110-35'
110-26'
78-40'
7<>03'
78-46'
78-30'
78-32'
78-33'
103-59'
104-13'
105M2'
104-36'
104M51
104-58'
116-51'

117-44'
117-4'
116-48'
116-50'
llfi57'
0
10.9
8.0
13.7
12.9
8.4
0
37
62
79
94.5
43.4
0
24
42
19
47
45
0
42
18
9
27.2
14.0
0
31
125
55
35
21
0

123
21
82
9.4
30
...
135
187
202
247
270
...
311
263
227
116
35

135
208
218
11
23
	
324
330
9
22
45
	
224
287
273
313
358
-_-

321
255
176
171.6
343
7,840
9, 500
11,006
14,050
12,129
10,800
6,870
8,354
6.807
5,628
7.356
6.520
6,600
8,000
9,600
6.700
8,900
8,100
3,360
2,100
2.200
2,300
2,400
2,840
7.700
7,800
9,200
7,700
8,200
7.200
410

6,750
5,360
3,400
417
4.700
.._.
2.66
6.88
7.86
5.79
6.13

0.70
0.02
0.27
0.09
-0.14

0.50
0.70
0.09
0.85
0.97
	

-0.63
-2.05
-0.81


0.00
0.00
0.00
0.00
0.00
	

0.90
4.11
0.64
0.18
2.67
Calculate
Target Cover SVr
...
evergreen
evergreen
rock
rock
evergreen
manzanlta
rock
rock
rock
rock
rock
	
pines
pine/rock
pines
pines
pines
	
forest, deciduous
forest, deciduous
forest, deciduous
forest, deciduous
forest, deciduous
...
vol. ash/cinder
pine
PJ
PJ
PJ
--.

1/2 PJ
rock
Scrub
rock
soil

yes
yes
no
no
yes

no
yes
yes
yes
no

yes
yes
yes
yes
yes

yes
yes
yes
yes
yes

yes
yes
yes
yes
yes


yes
yes
yes
yes
yes
                                                                                                                                                       (continued)

-------
                                                                              TABLE 4.   (Continued)
rvs
oo
Location Target
llumber Location Nane Nunber (lame
30 Yellowstone National Park

1

2
3
35. 36 Acadla National Park
1
2
39 Lake Tahoe Low
1
2
3
4
5
40 Lake Tahoe High
1
2
3
4
5
Administration
Building
Monitor Peak,
East Rtdoe
Bear Creek Basin
Poison Peak
Maintenance Area
Blue Hill
Mt. Battle
King's Beach
Deadnan Point
fiunbarrel
8455
Tahoe Mountain
Ellis Peak
State line Fire Lookout
Oeadrtan Point
Gunbarrel
R455
Tahoe Mountain
Ellis Peak
Lat
()
4502'

4510'

456'
44'52'
4422'
4426'
44M41
3914'
3907'
3856'
3R-531
3R55'
3904'
3913'
3907'
3856'
3fl53'
38-551
3904'
Long HI stance
(W) (km)
11043'

nn39'

11037'
iifvsn'
6fllfi'
6R-151
6904'
12002'
119-561
11955'
11956'
12n02'
12012'
120or
U9056'
11955'
m-se1
I?no2'
12012'
0

22.7

17.5
16.7
0
27
67
0
15.5
34.5
40
36
23.5
0
14.5
34
39.5
35.5
24
Azimuth
Angle
n
...

21

27
127
...
2fl5
256
	
157
167
170
1B2
218
	
161
169
172
1(14
222
Elevation
(feet)
6,267

9,3on

8,000
8,700
5(10
800
1,000
6,234
6,400
7,200
8.440
6,800
8.730
7.021
6,400
7,200
8,440
6,800
8,730
Elevation
Angle ()
....

0.04

0.03
0.04
---
0.00
0.00

0.00
0.01
0.02
0.01
0.03
	
-0.01
0.00
0.01
0.00
0.02
Target Cover
...

pine

pine above mining
pine
...
forest
forest
	
forest
forest
forest
forest
forest
	
forest
forest
forest
forest
forest
Calculate
svr


yes

yes
yes

yes
yes

yes
yes
yes
yes
yes

yes
yes
yes
yes
yes

-------
TABLE 5.  INHERENT SPECTRAL CONTRASTS AS A FUNCTION OF  VEGETATION,  LIGHTING
          AND WAVELENGTHS
                                        Wavelength (nanometers)
                                   405       450       550       630
Vegetation

     Shade                        -0.92     -0.92     -0.87     -0.83
     1/2 Shade                    -0.90     -0.88     -0.80     -0.74
     Sun                          -0.88     -0.84     -0.73     -0.65

Half Vegetation

     Shade                        -0.91     -0.91     -0.86     -0.82
     1/2 Shade                    -0.88     -0.83     -0.70     -0.60
     Sun                          -0.86     -0.75     -0.53     -0.39
                                     29

-------
CAMERA NETWORK

     Color photography at some sites was initiated  during  the  fall of  1979
to document the effects of changing  visual  air quality  on  various vistas.
Table 6 indicates the camera location,  starting date, direction of view  (azi-
muth angle) and teleradiometer targets  for  the camera network.  A 135-mm lens
provides a 14 view.  The camera was typically centered  on the teleradiometer
target.  Photographs were taken twice daily,  at 9 a.m.  and 3 p.m. local  time.
                                     30

-------
TABLE 6.  CAMERA NETWORK

Location Name
Grand Canyon National Park


Bryce Canyon National Park


Dinosaur National Monument

Mesa Verde National Park


Olympic National Park

Navajo National Monument

Big Bend National Park


Theodore Roosevelt National
Memorial Park
Colorado National Monument

Chiricahua National Monument

Shenandoah National Park



Azimuth Angle
293
163
96
120
20
311
243
180
220
200
185
52
336
325
260
112
50
22
195
254
350
88
263
116
330
go
22
45
Teleradiometer
Target #
2
4
5
1
4
5
2
4
1
Shiprock
3
2
4
1
2
1
2
3
1
2
2
4
2
4
2
3
4
5
Starting Date
10/1/79


11/1/79


9/1/79

9/1/79


4/30/80

3/6/80

9/4/79


9/4/79

1/12/81

6/5/81

5/5/80



                                     31

-------
                               DATA PROCESSING

     The flow of data from observation to final  graphics is shown  in Figure 10.
Each day the observer recorded the date, location code,  meteorological  and
snow codes, ratios and target radiance values on a data  sheet.   These data
sheets were mailed to the John Muir Institute-Visibility Research  Center (VRC)
each month where they were visually checked for  obvious  errors.   Operators  were
notified when errors appear and changes were suggested.   The data  were key-
punched on cards, verified, and computer-stored.  The ratios were  checked man-
ually for several kinds of errors or anomalies.

     Editing was designed to produce a data set  of uniform quality.   Data that
failed the editing tests were maintained, though specifically labeled, in the
time plots of apparent contrast.  Raw and edited data could then be  compared
in order to help observers and analysts reduce the occurrence of these errors
in the future.  Three tests were applied to each measurement:  "in sky,"
"Rayleigh contrast," and "spectral  consistency"  tests.   The "in  sky" test
assumes that contrasts between -0.01 and +0.01 occur only when  the teleradi-
ometer was mistakenly aimed so that both sky and target  detector readings
were taken in the sky.  The "Rayleigh contrast"  test rejects apparent con-
trasts that are less than (more negative than) the lowest possible calculated
contrast for a dark target viewed through an unpolluted  or a Rayleigh atmo-
sphere.  The "spectral consistency" test identifies spectral  ratios  that
significantly departed from the monthly mean of  the ratios at that wavelength.
It is based on an assumption that for dark targets, departures  for all  four
wavelengths would tend to vary in a similar way.  If the departure of a ratio
differed too greatly from concurrent ratios at other wavelengths,  it was re-
jected.  Details of this test are discussed in Appendix  A.  None of  these
questionable apparent contrasts are used in statistical  computations.

     Although the teleradiometer was used to measure the apparent  spectral
ratio at four wavelengths, only the 550-nm ratios were  used to  compute stan-
dard visual range because the human eye has its  peak response at the 550-nm
central wavelength of the green filter.

     Summary statistics were computed monthly, seasonally and for the entire
period of record.  The geometric mean is the appropriate averaging statistic
because standard visual range is log-normally distributed.  The  90-percent
confidence limits are one measure of the variability of  the individual  stan-
dard visual range.  They are related to the standard deviation  and the number
of readings.  If the confidence intervals around two means do not  overlap,  it
can be concluded that at a 90-percent confidence level  the two  means are sig-
nificantly different.
                                     32

-------
           Three times daily: Observers record
           codes. R and tNr on data sheet
         (Data sheets for each month sent to VRC I
Data sheets visually scanned for errors
                          Yes
          Data sheets key punched and verified
                 I
          Data cards entered into computer!
                  
          "In Sky" test
          Cr (A = 550)z- 0.01, 0, +0.01
                                          Yes
                      No
           "Rayleigh Contrast" test
           Cr (550) < (C Rayleigh - 0.05 )
                                          Yes
                                                   Notify operators of change needed
                                                   to eliminate errors
                                                   Correct errors by hand, if possible I
                                         Reading rejected by "in sky" test
                                         Reading rejected by "Rayleigh contrast"
                                         test
                      No
          "Special Consistency" test
          Does each reading significantly depart from
          value expected if all 4 spectral ratios are
          consistent
                 I
                                         Yes
                                                 Reading rejected by 'relative
                                                 departure' test
           No
          plot Cr (550) for the month for each location
         Combine apparent contrasts for 3 months
         to make season
          Is the target cover adequate
                                        No
                                        Drop these Cr from any further
                                        computation.
                      Yes
          Is the target snow-free
                                        No
                                        Don't include these readings in
                                        statistics
                      Yes
         Compute standard visual range
         statistics for each location
          Plot SVR cumulative frequency.
          histogram, and time plots
Figure 10.    Flow of  data from  manual  teleradiometers  to  final  graphics.
                                          33

-------
                              SUMMARY OF RESULTS

     Teleradiometer data collected during fourteen seasons of monitoring are
summarized in Table 7 and Appendices B and C.  Table 7 lists seasonal  statis-
tics of standard visual  range calculations:  geometric mean, 90% confidence
intervals, and the number of valid measurements collected at each site.   Since
snow covered targets are not used in standard visual range calculations, the
winter seasons at a number of the locations have very few valid  measurements.
The values calculated for these winter seasons should be used with care.

     The Big Bend, Chiricahua, and Death Valley sites all have targets  which
are sparsely vegetated.   Standard visual ranges calculated at these sites are
intended for interseason comparison at each location and are not recommended
for comparison with other locations.

     Appendix B contains time plots for each location of monthly geometric
mean standard visual range.  The 90% confidence levels are indicated by  cross
hatching.  In order to generate meaningful  statistics, only those months that
have 11 or more valid measurements of standard visual range are  plotted.

     The data in Table 7 and Appendix B show strong seasonal  variations  in
standard visual range at all the monitoring locations.  Maximum  values  occur
during the fall and winter months with minimums during the spring and  summer.
The causes of these seasonal fluctuations are not addressed in this report.
Further studies in this  area are in progress.

     Appendix C contains total cumulative frequency distributions of standard
visual range for each location.  These plots represent all the valid standard
visual range measurements made at a location during the period that monitoring
was in effect.  Frequency of occurrence of standard visual range at each moni-
toring site can be taken from these distributions.  The 10%, 50%, and  90%
levels are indicated on  each plot.  Figure 11 is a map showing the 50%  levels
for sites with at least  one year of data.  Isopleths on the map  indicate that
the area of greatest measured median visibility is primarily the Colorado
Plateau.

     Though the camera monitoring network was responsible for collecting over
20,000 color slides, the qualitative nature of this type of information  does
not lend itself to data  summary.  This photographic record has been made avail-
able to researchers investigating western regional visibility, and has  been
proven to be a valuable  source of information.
                                     34

-------
                                   TABLE  7.   SEASONAL MEAN STANDARD VISUAL RANGE (KM)a
Season1"
Year
Su inner
1978


Fall
1978


Winter
1978/1979


Spring
1979


Summer
1979


Fall
1979


Winter
1979/1980


Spring
1980


Summer
1980


Fall
1980


Winter
1980/1981


Spring
1931


Summer
1981


Fall
1981


Canyonlands
Island in
the Sky
1
NO
DATA


200
(194-
206)
366
251
(184-
341)
7
169
(161-
178)
90
189
(185-
193)
413
190
(185-
195)
456
194
(177-
213)
51
182
(171-
193)
99
190
(187-
193
482
206
(200-
211)
353
241
(209-
278)
10
192
(185-
200)
168
165
(162-
169)
498
205
(200-
211)
369
Grand
Canyon
2
172
(168-
177)
642
208
(203-
213)
809
248
(213-
288)
24
159
(151-
166)
236
178
(175-
181)
1.023
194
(190-
199)
990
276
(265-
287)
296
130
(122-
138)
269
159
(156-
162)
1,122
219
(213-
224)
910
264
(258-
271)
626
180
(176-
185)
706
138
(135-
140)
944
203
(198-
208)
1.091
Canyonlands
Hans Flat
3
NIC



NI



NI



136
(130-
142)
81
166
(164-
169)
672
176
(172-
180)
506
206
(193-
220)
75
151
(145-
157)
126
158
(156-
161)
583
180
(176-
184)
426
174
(165-
182)
252
NI



NI



NI



Bryce
Canyon
4
178
(173-
184)
228
208
(202-
215)
327
259
(240-
279)
30
144
(138-
150)
114
170
(166-
173)
920
195
(190-
199)
757
289
(280-
299)
218
129
(117-
142)
26
138
(135-
142)
662
223
(219-
228)
798
280
(274-
286)
591
192
(187-
197)
453
159
(157-
162)
793
206
(201-
211)
600
Capitol
Reef
5
190
(185-
194)
570
215
(209-
222)
509
NO
DATA


171
(163-
179)
209
175
(171-
179)
682
189
(184-
195)
580
216
(203-
230)
5
164
(157-
m)
245
164
(160-
168)
672
206
(199-
214)
357
159
(109-
231)
15
204
(193-
216)
179
160
(156-
163)
707
207
(201-
214)
513
Dinosaur
6
192
(186-
198)
223
NO
DATA


205
(147-
286)
8
168
(153-
185)
14
177
(174-
181)
593
192
(187-
196)
414
NO
DATA


102
( 96-
109)
3
151
(145-
157)
356
203
(199-
208)
457
209
(191-
229)
65
166
(160-
173)
255
145
(142-
148)
357
NI



Mesa
Verde
7
169
(164-
174)
207
185
(180-
191)
336
NO
DATA


153
(142-
165)
48
182
(178-
186)
482
184
(179-
189)
323
189
(148-
242)
2
139
(123-
156)
113
176
(172-
180)
538
201
(197-
205)
466
235
(225-
246)
141
190
(185-
195)
276
153
(150-
157)
456
172
(166-
178)
443
Olympic
8
NI



NI



NI



NI



NI



NI



NI



140
(124-
158)
65
138
(126-
151)
75
152
(139-
167)
128
178
(155-
205)
66
151
(129-
176)
36
NI



NI



Wupatki
9
166
(154-
179)
22
122
(114-
131)
254
188
(161-
218)
- 28
201
(169-
233)
16
159
(153-
166)
259
162
(155-
168)
339
215
(191-
243)
57
141
(133-
148)
80
158
(153-
163
315
180
(172-
189)
229
166
(149-
187)
52
170
(162-
178)
201
141
(137-
145)
459
176
(169-
183)
402
Navajo
10
192
(177-
209)
68
191
(185-
198)
511
NO
DATA


160
(102-
169)
154
164
(160-
167)
632
175
(171-
180)
474
264
(181-
384)
7
145
(138-
153)
165
168
(164-
171)
678
230
(224-
237)
564
256
(245-
267)
204
192
(185-
183)
332
152
(149-
155)
620
218
(211-
225)
465
Order of presentation for each  entry  1s geometric mean. (90% confidence Interval), and number of values.   Calculated
 for snow-free targets regardless  of cloud  condition.
"Seasons are:   Summer - June, July, August; Fall - September, October, November; Winter - December,  January,  February;
                 Spring - March, April, May.
CN1  No Instrument.
                                                          35

-------
                                                   TABLE 7.  (Continued)
Season
Year
Summer
1978


Fall
1978


Winter .
1978/1979


Spring
1979


Summer
1979


Fall
1979


Winter
1979/1980


Spring
1980


Summer
1980


Fall
1980


Winter
1980/1981


Spring
1981


Summer
1981


Fall
1981


Chaco
187
(181-
193)
115
203
(198-
208)
270
NO
DATA


188
(175-
201)
22
198
(195-
202)
250
198
(194-
202)
331
298
(271-
327)
2
176
(169-
183)
67
180
(177-
183)
384
213
(207-
219)
190
257
(240-
275)
58
177
(172-
183)
102
163
(160-
167)
183
208
(195-
222)
68
Canyon"1
11
NO
DATA


225
(201-
251)
11
264
(228-
302)
3
184
(166-
205)
12
184
(177-
190)
87
190
(184
197)
103
348
(348-
348)
1
211
(192-
231)
23
237
(226-
249)
119
195
(185-
205)
65
210
(197-
224)
64
188
(180-
197)
43
167
(159-
176)
48
208
(188-
230)
23
Bandelier
12
172
(166-
177)
335
155
(151-
158)
681
226
(207-
247)
33
284
(284-
284)
1
148
(145-
150)
801
149
(146-
153)
689
186
(178-
194)
191
174
(169-
180)
210
164
(161-
167)
940
176
(172-
180)
613
221
(213-
228)
335
187
(182-
192)
519
147
(144-
150)
828
176
(172-
181)
659
White Sands
13
118
(111-
124)
155
125
(119-
131)
269
190
(174-
207)
89
143
(137-
148)
297
114
(111-
118)
418
115
(111-
119)
424
159
(153-
165)
329
132
(128-
136)
423
119
(115-
113)
411
139
(134-
145)
321
177
(171-
183)
356
141
(136-
145)
376
112
(109-
116)
322
133
(127-
139)
284
Carlsbad
14
157
(145-
171)
42
179
(163-
197)
55
245
(218-
275)
29
151
(132-
173)
19
139
(133-
145)
191
142
(136-
149)
174
206
(194-
219)
146
197
(169-
231)
13
NI



NI



NI



NI



NI



NI



Big Bend6
15
148
(140-
158)
234
130
(125-
136)
455
212
(192-
234)
75
163
(157-
168)
579
154
(150-
158)
1,008
146
(142-
150)
905
174
(168-
179)
8C2
168
(163-
173)
838
138
(135-
141)
1,054
146
(141-
152)
577
208
(202-
215)
965
183
(178-
189)
1.043
139
(135-
143)
1,156
143
(139-
148)
1.040
Roosevelt
16
NI



NI



NI



120
(111-
130)
100
113
(109-
118)
366
154
(147-
161)
282
230
(206-
258)
54
100
( 95-
105)
246
131
(127-
135)
389
195
(185-
205)
291
211
(197-
227)
194
130
(122-
138)
213
115
(110-
121)
368
135
(126-
145)
225
Cave
17
NI



NI



NI



123
(105-
142)
34
145
(138-
154)
301
179
(162-
198)
102
NO
DATA


111
(102-
122)
100
163
(157-
170)
485
194
(180-
210)
163
209
(167-
262)
48
185
(171-
200)
146
159
(152-
165)
523
128
(117-
140)
123
Colorado
National
Monument
18
NI



NI



NI



!



NI



NI



NI



NI



177
(174-
180)
877
204
(199-
208)
681
235
(228-
242)
427
190
(182-
199)
243
171
(167-
175)
659
183
(176-
189)
307
Rocky
Mountain
19
NI



NI



NI



Ni



NI



NI



HI



NI



157
(150-
165)
481
239
(226-
253)
332
278
(258-
300)
211
221
(197-
247)
120
193
(181-
206)
269
199
(185-
214)
310
dChaco Canyon values  for target  6 are  In the second column, all other targets In the first columns.
eThis site has no satisfactory targets.  Visual  range values should not be compared to other locations.
                                                          36

-------
                                             TABLE 7.  (Continued)
Season
Year
Sunnier
1978
Fall
1978
Winter
1978/1979
Spring
1979
Sunmer
1979
Fall
1979
Winter
1979/1980


Spring
1980


Sunnier
1980


Fall
1980


Winter
1980/1981


Spring
1981


Summer
1981


Fall
1981


Chiricahua6
21
NI

NI

Nl

NI

NI

NI

NI



NI



NI



NI



NI



Nl



14S
(141-
148)
388
244
(236-
253)
426
Grand Tetons
22
NI

NI

Nl

NI

NI

NI

NI



NI



152
(147-
157)
470
172
(166-
178)
539
NO
DATA


NO
DATA


147
(143-
150)
1.018
151
(146-
156)
755
Shenandoah
23
NI

NI

NI

NI

NI

NI

NI



50
( 47-
54)
179
39
( 37-
41)
489
63
( 60-
67)
377
NO
DATA


35
( 31-
40)
24
41
( 39-
44)
399
72
( 67-
77)
185
Capulin
24
NI

NI

NI

NI

NI

NI

NI



137
(131-
143)
338
139
(136-
143)
973
207
(201-
213)
819
273
(267-
280)
870
180
(175-
187)
606
160
(156-
164)
849
201
(195-
207)
873
Death Valley6
28
Nl

NI

NI

NI

NI

NI

250
(225-
277)
36
171
(162-
181)
294
145
(138-
152)
420
235
(226-
244)
535
294
(285-
303)
501
204
(195-
213)
495
142
(137-
148)
616
220
(211-
230)
487
Yellowstone
30
NI

NI

NI

NI

NI

NI

NI



NI



NI



NI



NI



NI



177
(171-
184)
529
161
(151-
171)
338
site has no satisfactory targets.  Visual range values should not be compared to other locations.
                                                   37

-------
                                                 Texas
    123 Median standard visual range (km)
      I Station number
Figure 11.  Median standard  visual  range  (km),  summer 1978 through fall  1981,
                                     38

-------
                                  REFERENCES

Environmental Protection Agency (EPA), "Protecting Visibility:  An EPA Report
     to Congress," EPA 450/5-79-008 (1979).

Environmental Protection Agency (EPA), "Interim Guidance for Visibility Moni-
     toring," EPA-450/2-80-082 (1980).

Malm, W., "Considerations in the Measurement of Visibility," Journal  of the
     Air Pollution Control  Association, _29, 1042 (1979).

Malm, W. C., M. Pitchford, A. Pitchford, "Site Specific Factors Influencing
     the Visual Range Calculated from Teleradiometer Measurements," Atmos.
     Environ. (In Press) 1982.

Middleton, W. E. K.  1952.   Vision through the atmosphere.  University of
     Toronto Press, Toronto, Canada.
                                     39

-------
              APPENDIX A



THE SPECTRAL CONSISTENCY EDITING TEST
                 40

-------
     The arithmetic  mean  and_standard deviation of the ratios of target to sky
apparent spectral  radiance  (R  and  SD) are computed for a 1-month period for
each target, time  of day  and wavelength.  The relative departure (DEP) of each
ratio (R) is computed using the  relation

          DEP = ABS  (^-^  )

where ABS is the absolute value  of expression in parentheses.

     The test can  be graphically illustrated as shown below.  The dots mark
the relative departures of  specific  spectral ratios.  These are used to compute
the least squares  fit straight line.  If the difference between a point and
the line is less than 0.8 then the ratio is accepted.  The 0.8 was selected
from tests on early  Grand Canyon data as appropriate to eliminating obviously
incorrect ratios.
         CD
         a
         a>
        a
         a>
         O>
        QC
              1-
                                      Example of
                              Spectral Consistency Test

                                   Data is accepted
                                      for A <0.8
 A =0.77
                 4=0.22
                                          Least Squares Line
                                      550
         630
                                  Wavelength
                                     41

-------
                 APPENDIX B

TIME PLOTS OF MONTHLY STANDARD VISUAL RANGE
   GEOMETRIC MEAN, 90% CONFIDENCE LEVELS
                    42

-------
         CRNYONLRNDS  NRTIONflL PRRK,  ISLflND  IN THE SKY
                  MONTHLY STRNDRRD VISUflL RRNGE, GEOMETRIC MERN
     300-
   LiJ


   CE
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     200
   CO
   Q
      100~
   CE
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       0-
           i i i  i i i  i i i i  i ii i i i  r i i  i i i  i i i  i i i i  i i i  i i i  i i i  i i i
JJfl S ON D

  1978


                   JFMflMJJRSOND


          JFMnMJJRSOND
                                                                1
                                                                8
JFMflMJJflSON
1979            1980
       MONTH
                                                       1981
                                                               82/02/18.

-------
   400
   300-^
CE
   200-^
CO
Q
g 100 
CE
h-
CO
     0-
           GRflND CRNYON NRTIONRL  PflRK
        MONTHLY STflNDflRD VISUflL RflNGE, GEOMETRIC MEflN
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        JJflSO ND

          1978
                   I
                      i
         JFMflMJJflSOND
                            i
JFMflMJJflSOND
               1979            1980
                       MONTH
JFMflMJJRSON

    1981
                                                                 82/02/18.

-------
              CRNYONLflNDS NflTIONRL PfiRK,  HRNS FLRT
                 MONTHLY STRNDRRD VlSURL RHNGE, GEOMETRIC MERN
     300-
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CD

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  1978
                 i  i i
                                 ^
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                          1  1
                                JFMRMJJnSOND
  i  i i i  i i i  i i
                      1979            1980
                             MONTH
JFMflMJJflSON

    1981
                                                              82/02/18.

-------
                      BRYCE CRNYON NflTIONRL PRRK
                   MONTHLY STRNDRRD VISURL  RRNGE, GEOMETRIC MERN
     300-
  UJ
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                                                              ii i  r
               11
          J Jfl S 0 N D
             197Q
                  JFMRMJJflSOND
JFMRMJJRSOND
                        1979            1980
                                MONTH
JFMRMJJHSON
    1981
                                                                    82/02/18.

-------
                  CRPITOL  REEF  NRTIONflL  PflRK
               MONTHLY STRNDRRD VISURL RRNGE, GEOMETRIC MERN
   400
   300 
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              1979            1980
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                                                  1981
                                                             82/02/1B.

-------
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                 JFMflMJJflSOND
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                       1979
                                       1980
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    1981
                              MONTH
                                                               82/02/1B.

-------
   400
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                                    1
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      1979
      1980
    1981
                               MONTH
                                                                82/02/18.

-------
   400
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                       1979
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JFMflMJJflSON

    1981
                               MONTH
                                                                82/02/18.

-------
                   WUPRTKI   NRTIONRL  MONUMENT

                MONTHLY STRNDflRD VISURL RflNGE,  GEOMETRIC MERN
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    1981
                                                                82/02/18.

-------
                     NflVflJO  NRTIONflL MONUMENT

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-------
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1979            1980
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1981
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-------
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-------
   400
             WHITE  SRNDS  NflTIONRL MONUMENT

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-------
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                MONTHLY STRNDRRD VI SURE RRNGE, GEOMETRIC MERN
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-------
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                                 MONTH

-------
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-------
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                    1979            1980

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    1981

-------
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             1978
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              1979
      1980
1981
                                 MONTH

-------
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1979
                                       1980
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     1981
                                MONTH

-------
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1979
                                      1980
JFMRMJJRSON

    1981
                                  MONTH

-------
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             1978
              JFMRMJJRSOND
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1979
                                    1980
JFMRMJJflSON

    1981
                                 MONTH

-------
     400
     300-
   LiJ
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                                    1
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              1979            1980

                      MONTH
JFMRMJJRSON

    1981
                                                                92/02/19.

-------
TflRGET  6 CHflCO  CRNYON  NflTIONflL  CULTURRL PRRK
        MONTHLY STfiNDflRD VISURL RRNGE, GEOMETRIC MEflN
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  137 B
1979
1980
1981
                     MONTH

-------
      DEflTH  VRLLEY NRTIONRL  MONUMENT
      MONTHLY STRNDRRD VISUflL RRNGE, GEOMETRIC MERN
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1978
1979            1980
       MONTH
1981
                                                  82/02/18.

-------
oc
  LU
  or.
  o/
  CO
  o
  Q/
  CT
  Q
  CL
  h-
  CO
400  r r T
     300 
     200-
100 
       0-
                    YELLOWSTONE   NnTIONRL PflRK
                  MONTHLY STRNORRD VISURL RflNGE, GEOMETRIC MEflN
                      ~ TI ~T

J J R 3 0 N D

   1978
                             _L.L
                                     I I  I I
                   J F M R M J J R 3 0 N D J FMRMJJR30ND
                         1979
                                    1980
JFMHMJJflSON

    1981
                                MONTH

-------
                              TflHOE   LOW
                 MONTHLY STRNDflRD VISURL RflNGE, GEOMETRIC MEflN
   400
   300-
LLJ
C!D
Z
CE
   200 
CO
Q
Q/
cn
Q
Z
cn
i
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100
     0-
         I I  I lllIIIIIIIITITIIIITIIiTI 1 T I I  I I  I T I 1^ I I  T T
         I I  I I  I I
                I  I I I  I I  I I  I I  I
             i i  i i i  i i  i i  i i
 i  i i  i
                                                                    1
        J Jfl 5 0 NO



           1978
               JFMflMJjnSOND
            JFMflMJJflSOND
JFMflMJJRSON
1979             1980

        MONTH
                                                       1981
                                                                   82/03/04.

-------
                              TRHOE HIGH
                MONTHLY STRNDflRD VISUAL RRNGE, GEOMETRIC MERN
   400
         I I I
                                                     II i  i i i  i r
   300-
UJ
cr
o/
CO
   200
Q
QZ
CE
CD
~Z.
cr
h-
CO
100 
     0-
                      I I  I I  I I I  I I
                                    I I  I I  I I I  I I
                                                               i
        J Jfl S 0 N D

          1978
               JFMRMJJnSOND
JFMnMJJRSOND
JFMRMJJRSON
                     1979            1980

                            MONTH
                      1981
                                                                  B2/03/04.

-------
                         APPENDIX C



CUMULATIVE FREQUENCY DISTRIBUTIONS OF STANDARD VISUAL RANGE
                            71

-------
UJ
O
~z.
cr
cr
ZD
CO
Q
a/
a:
cr
f
CO
       CRNYONLnNDS NnTIONRL PRRK,  ISLRND  IN THE SKY

                        FROM SEP 78 TO NOV  81

                CUMULRTIVE FREQUENCY OF STflNDRRD VISUflL RflNGE
600

500

400


300



200
100
 60



 40


 30



 20
                          i   iii
                              I
I   I
        PERCENT 3VR (KM)

         10    113

         50    173

         90    264
                   1      10       50       90      99

                   CUMULRTIVE  FREQUENCY  (%)

-------
CO
                    GRRND CRNYON  NflTIONRL PflRK
                          FROM  JUL 78 TO NOV  81
                  CUMULRTIVE FREQUENCY OF STRNDRRD VISURL RRNGE


z:
- '
UJ
CE
_J
CE
v
ID
cn
i  i
Q
CE
0
CE
1 
CO

600
500
400
300

200

100
80
60
40
30
20
i i i i I i i i i i i
-
X
r* -
-j/
[ +S \
: + /X ~-
' */ -
/
" /^ "
PERCENT SVR (KM) -
10 88
50 162
90 299
i t i t i 1 i i i i t
1 10 50 90 99
                     CUMULRTIVE  FREQUENCY  (%)
                                                            B2/03/0P.

-------
cb
en
Q/
_J
CE
CO
Q
Q/
CE
Q
cr
CO
            CRNYONLRNDS  NRTIONRL PflRK,  HflNS FLRT
                         FROM  MflR  79 TO FEB  81
                CUMULRTIVE FREQUENCY OF STflNDflRD VISUflL RRNGE
600
500
400

300


200
100
 80

 60


 40

 30


 20
                             III
                               I
PERCENT SVR (KM)
 10
 50
 90
111
163
240
                                     j	I	L
                   1       10        50        90
                   CUMULRTIVE FREQUENCY  (%)
                                               99
                                                             82/03/03.

-------
LU
CJ3
Z
CE
cr
13
CO
Q
Q/
cr
Q
cr
CO
600

500

400


300



200
100

 80


 60



 40


 30



 20
                   BRYCE  CRNYON  NflTIONFL PRRK
                         FROM  JUN 78  TO  NOV  81
                CUMULflTIVE FREQUENCY OF STRNDflRD VISUflL RRNGE
                             T	T
PERCENT SVR IKH)
 10

 50

 90
100

174

302
                           I   I  I
                   1       10       50       90      99

                   CUMULRTIVE  FREQUENCY  (%)

-------
UJ
O
z
cr
cr
=3
CO
Q
OI
Q
cr
j
CO
600
500

400

300


200
100
 60


 40

 30


 20
                   CRPITOL  REEF NRTIONRL  PflRK
                         FROM  JUN 78 TO NOV  81
                CUMULATIVE FREQUENCY OF  STRNDflRD VISURL RRNGE
                                   I
                                 I  I  I
PERCENT SVR (KH1
                                                   10
                                                   50
                                                   90
     98
     165
     280
                   1       10        50       90     99
                   CUMULATIVE FREQUENCY  (%)

-------
LU
ex
Q/
CE
ID
CO
Q
Q/
CL
cr
i
CO
600

500

400

300


200
100

 80

 60


 40

 30


 20
                   DINOSRUR  NRTIONRL MONUMENT
                          FROM  JUL  78  TO  RUG  81
                CUMULATIVE FREQUENCY  OF STRNDRRD VISURL RflNGE
                                    I
                                     I    I
                                    1
PERCEMT 3VR (CT)

 10    102

 50    160

 90    252
                   1      10       50        90      99

                    CUMULRTIVE  FREQUENCY  (%)
                                                              82/B3/0n.

-------
j
(X
  cr
  cr
  :D
  CO
  a
  a/
  cr
  a
  cr
  CO
                       MESH VERDE NRTIONflL  PRRK

                            FROM  JUL 78 TO NOV 81

                   CUMULRTIVE FREQUENpY OF STRNDRRD VISURL RRNGE
       600

       500


       400


       300




       200
100


 80



 60




 40



 30




 20
                                       I
                                 I  I   I
PERCEHT SVR (KM)
 10

 50

 90
101

158

247
                      1       10        50       90      99

                      CUMULATIVE  FREQUENCY  (%)
                                                                 B2/03/K1.

-------
.vo
    LU
    cr
    cr
    Z)
    CO
    Q
    cr
    Q
cr
\
CO
600

500


400



300




200
100


 80



 60




 40


 30




 20
                         OLYMPIC  NRTIONRL   PRRK

                             FROM RPR 80 TO MfiY  81

                    CUMULflTIVE FREQUENCY OF STflNDnRD VISURL RflNGE
                                    r  i
                                I
I  I
           PERCENT SVR (KH)
                                                       10

                                                       50

                                                       90
                62

                128

                263
                       1       10       50       90      99

                       CUMULflTIVE  FREQUENCY  (%)

-------
oo
o
   LU
   O
   z
   cr
   cr
   ZD
   CO
   Q
   Q/
   cr
   Q
   cr
   CO
                     HUPRTKI   NRTIONRL  MONUMENT
                            FROM  RUG  78  TO  NOV  81
                   CUMULATIVE FREQUENCY  OF STflNDRRD VISUflL RflNGE
600

500

400


300



200
100

 80


 60



 40


 30
        20
                                       -K
                          4-
PERCENT SVR tKM)
 10

 50

 90
84

147

257
                                        JL_J	L
                      1       10        50        90

                      CUMUinTIVE FREQUENCY  (%)
                                               99

-------
oc
  LU


  cr
  cr
  ID
  CO
  Q
cr
Q
  cr
  \
  CO
     600

     500


     400


     300




     200
100


 80


 60




 40


 30




 20
                       NflVflJO  NRTIONRL  MONUMENT

                            FROM  RUG 78 TO NOV 81

                   CUMULATIVE FREQUENCY OF STRNDRRD VISURL  RRNGE
                                     i
                                    I

                                i   i  i
                                    1
i  i  i
                                                     PERCENT SVR (KM)
                                                    10

                                                    50

                                                    90
                  90

                  162

                  289
                   1       10        50        90

                    CUMULRTIVE FREQUENCY  (%)
                                                       99
                                                                B2/03/0n.

-------
CO
1X3
  UJ
  CL
  Q/
  cr
  ID
  CO
  Q
  Q/
  cr
  Q
  cr
  CO
600

500

400


300



200
100

 80


 60



 40


 30
        20
               CHRCO CRNYON   NRTIONflL  CULTURRL  PflRK
                           FROM  JUL  78 TO  NOV  81
                  CUMULflTIVE FREQUENCY OF STRNDflRD VISUflL RflNGE
                            i   ill
                                \  i   i
                                                       -f
PERCENT SVR (KH)
 10

 50

 90
122

175

251
                     1       10        50        90      99

                     CUMULATIVE FREQUENCY  (%)

-------
00
  LJJ
  CE
  Q/
  cr
  ID
  CO
  Q
  Q/
  cr
  Q

  cr
  CO
600

500

400


300



200
100

 80


 60



 40


 30



 20
                    BflNDELIER  NflTIONRL MONUMENT

                            FROM JUL  78 TO NOV 81

                   CUMULRTIVE FREQUENCY OF STflNDHRD VISUflL RRNGE
                                      I
                                 I  I   T
-f
                        PERCENT  SVRJICMI
                         10

                         50

                         90
91

149

245
                                J	I
                      1       10        50       90      99

                      CUMULRTIVE FREQUENCY  (%)
                                                                KJ/tB/IB.

-------
  LjJ
oo
-P.
  CT
  Q/
  CE
  D
  CO
  Q
  Q/
  CT
CE
h-
CO
600

500

400


300



200
100

 80


 60



 40


 30



 20
                  NHITE SRNDS   NRTIONRL  MONUMENT
                            FROM JUL  78  TO  NOV  81
                  CUMULFVriVE FREQUENCY  OF STRNDflRD VISURL RRNGE
                                r  i  i
                               I
1  I
                                .	I	L
I  I  I
             PERCEMT SVR (ICM1
                                                     10

                                                     50

                                                     90
                  67

                  117
                  203
               1       10        50       90

               CUMULATIVE FREQUENCY  (%)
                                                      99

-------
oo
in
   LU
   cr
   o/
   a:
   ID
   en
   Q
   a/
   a:
cr
i
CO
600

500


400



300




200
100


 80



 60




 40



 30




 20
                    CRRLSBRD CflVERNS  NRTIONRL PRRK

                             FROM  JUL  78  TO  RPR  80

                    CUMULATIVE FREQUENCY OF STflNDRRD VISURL RflNGE
                                 Til
-f
                   	L
                               I
              I   1
          1
                         PERCENT SVR (KH1
                                                       10


                                                       50


                                                       90
                              81

                              144

                              256
                      1       10        50        90

                       CUMULRTIVE FREQUENCY  (%)
                                               99
                                                                 B2/03/1B.

-------
00
01
   UJ
   (>
   Z
   CT
   CE
   H)
   (D
   o
   a/
   a:.
   a
   a:
   CO
600
500
400
300

200
100
 80

 60

 40

 30

 20
                 THEODORE  ROOSEVELT NHTIONRL  PRRK
                           FROM FEB 79 TO NOV  81
                  CUMULflTIVE FREQUENCY OF STflNDflRD VISURL RflNGE
                             i   iii
                               I
I  I  I
                               J	I  I
I	L	L
            PERCENT  SVR (KM)
             10
             50
             90
61
122
244
                     1      10       50       90     99
                      CUMULflTIVE  FREQUENCY  (%)

-------
oc
                     NIND CnVE   NflTIONRL  PRRK
                          FROM MRY 79 TO  SEP 81
                 CUMULRTIVE FREQUENCY OF STnNDRRD VISURL RRNGE


s:

UJ
en
Q/.
_j
CE
ZD
CO
1 	 1
Q
cr
Q
en
i 
CO
600
500
400
300

200
100
80
60
40
30
OfTl
1 1 1 1 1 I 1 1 i 1 1
-
/
7 ~
/
\ y }
y
y
- / -
/ PERCENT SVR JKH)
/ 10 70
50 137
90 269
! 1 1 1 1 1 1 1 1 1 1
                    1      10       50       90     99
                    CUMULflTIVE FREQUENCY  (%)

-------
00
00
   cr
   o/
   cr
   ID
   en
   cr
   a
cr
h-
CO
       600

       500


       400


       300




       200
100


 80


 60




 40


 30




 20
                      COLORRDO NflTIONRL  MONUMENT

                            FROM JUN 80 TO NOV 81

                   CUMULflTIVE FREQUENCY OF STfMDRRD VISUflL RflNGE
                                 I  I  I
                               I
1  I  I
             PERCENT SVR (KM)
                                                      10


                                                      50


                                                      90
                   112

                   173

                   268
                                  j	L
i  i  i
                             10
                               50
       90
                                                    99
                      CUMULRTIVE  FREQUENCY  (%)
                                                                B2/03/10.

-------
oo
10
   UJ
   (>
   ~ZL
   cr
   cr
   ID
   CO
  Q
  Q/
  cr
  Q
   cr
  CO
600

500

400


300



200
100

 80


 60



 40


 30



 20
                       ROCKY MT.   NflTIONflL  PRRK
                             FROM  JUN  80 TO NOV 81
                   CUMULflTIVE FREQUENCY OF STRNDRRD VISURL RRNGE
                                 I   I  I
                                I
                                 I   I  I
1
I  I  I
               PERCENT  3VR (KH1

                10   57

                50   134

                90   315
                      1       10        50       90      99

                       CUMULflTIVE FREQUENCY  (%)
                                                                  82/83/10.

-------
LU
en

-------
LU
o
cc
cr
ID
CO
a
a:
a
cr
\
CO
600
500
400

300

200
100
 80

 60

 40

 30

 20
                   GRRND TETON   NflTIONRL  PRRK
                          FROM  JUL  80  TO NOV  81
                CUMULRTIVE FREQUENCY OF STflNDflRD VISURL RflNGE
                              I  I  I
                                I
I  I
             PERCEHT SVRJtffl)
                                                    10
                                                    50
                                                    90
                  74
                  137
                  254
                                i	i
iii
                           10
                               50
       90
                                                    99
                    CUMULRTIVE FREQUENCY  (%)
                                                              B2/03/1B.

-------
                          A

                     SHEN|NDOflH  NflTIONRL  PflRK

                          FROM  MRY  80  TO OCT  81

                CUMULATIVE FREQUENCY  OF STRNDRRD VISUAL RflNGE
UJ
C>
cr
o/
cr
ID
en
a
cr
a
cr
\
CO
600

500


400



300




200
100


 80



 60




 40



 30
     20
                   T
                                         T
                 T
                                      I  I  I
               PERCEKT SVR (KH1


                10   15

                50   39

                90   98
                   1
                      10
50
90
99
                    CUMUinTIVE FREQUENCY  (%)
                                                              B2/B3/IB.

-------
ID
00
   CE
   CE
   ID
   CO
   Q/
   CC
   Q
CE
h-
CO
                 CflPULIN  MOUNTRIN NflTIONRL  MONUMENT
                            FROM  RPR  80  TO  NOV  81
                   CUMULRTIVE FREQUENCY OF STflNDflRD VISUflL RRNGE
       600

       500

       400


       300



       200
100

 80


 60



 40


 30



 20

            PERCENT  SYR (KM)
                                                     10
                                                     50
                                                     90
                  84

                  155
                  285
                                      i
i  i  i
              1       10       50       90

              CUMULATIVE  FREQUENCY  (%)
                                                      99
                                                               R3/B3/I1,.

-------
cr
(X
ZD
CO
Q
CL
Q
CL
I
CO
       TRRGET  6 CHRCO  CflNYON  NflTIONRL CULTURRL PflRK
                        FROM NOV 78 TO NOV 81
                CUMULATIVE FREQUENCY OF STflNDRRD VISUflL RRNGE
    600

    500

    400

    300



    200
100

 80

 60


 40


 30
     20
                          i   i  i  i  i  i i
PERCENT SVR (KM)
                                                  10

                                                  50

                                                  90
      113

      175

      272
                             i  i  i
                                i  i
                   1      10       50       90     99

                   CUMULRTIVE  FREQUENCY  (%)
                                                            B2/B3/11.

-------
in
UJ

Z
cr
   cr
   ID
   CO
   en
   Q
en
f
CO
       600

       500

       400


       300



       200
     100

     80


     60



     40


     30



     20
                   DEflTH  VRLLEY  NRTIONRL MONUMENT

                            FROM  FEB 80 TO NOV 81

                   cuMUinrivE FREQUENCY OF STRNDRRD visuni RRNGE
                             I   I   I
                                    I
I   I
        PERCENT  5VR 1KM)
                                                      10

                                                      50

                                                      90
              75

              145

              281
                      1       10        50        90      99

                      CUMULRTIVE FREQUENCY  (%)
                                                                BVYB3/09.

-------
  LU
  cr
ID
CTi
  cr
  ID
  CO
  cr
  a
cr
t
CO
600

500

400


300



200
100

 80


 60



 40


 30



 20
                     YELLONSTONE   NRTIONRL  PRRK

                            FROM  JUN  81  TO  NOV  81

                  CUMULRTIVE FREQUENCY  OF STflNDflRD VISUflL RRNGE
                                I  1  T
                               T
  i  i  r
               PERCENT SVRIKH)
                                                     10

                                                     50

                                                     90
                    71

                    141

                    278
                                i  i  i
i
                                      i  i  i
                     1       10        50        90

                      CUMULflTIVE  FREQUENCY  (%)
                                                99
                                                                82/03/1I.

-------
cr
o/
cr
ID
CO
Q
CL
a
en
t
CO
                               TRHOE  HIGH

                           FROM  JUN  81 TO NOV  81

                 CUMULflTIVE FREQUENCY OF STflNDRRD VISURL RflNGE
     600

     500


     400


     300




     200
100


 80


 60




 40


 30




 20
                                  11
PERttNT  5VR (KHI
                                                      10

                                                      50

                                                      90
      75

      144

      277
                               i   i  i
                    1        10        50        90      99

                    CUMULRTIVE FREQUENCY  (%)
                                                                82/03/11.

-------
1C
00
   UJ
   cr
   cr
   ID
   CO
   Q
   cr
   Q
   cr
   i
   CD
                                  TflHOE   LON
                              FROM  JUN  81  TO NOV  81
                    CUMULflTIVE FREQUENCY  OF STRNDRRD VISUflL RRNGE
600
500
400

300


200
100
 80

 60


 40

 30


 20
                                   T  I  I
J	I	L
                                         1
J	L_JL
                      PERCtiMT  SVR (KH)
                       10
                       50
                       90
                    70
                    135
                    259
                1       10        50        90
                CUMULRTIVE FREQUENCY  (%)
                                                          99
                                                                    62/03/11.

-------
LU

Z
cr
CE
ID
CO
a
cr
a
cr.
h-
CO
     600

     500


     400


     300




     200
     100

     80


     60



     40


     30



     20
                      BIG  BEND NRTIONflL  PflRK

                         FROM  RUG  78  TO  NOV  81

                CUMULRTIVE FREQUENCY  OF STflNDflRD VISURL RflNGE
                              7  I  I
                                   1.
             PERCEMT SVR fKM)
              10


              50


              90
59

126

268
J	I	L
                   1       10     .  50        90      99

                   CUMULRTIVE  FREQUENCY  (%)

-------