&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.
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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
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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.
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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,
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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,
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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
U1nt»s. (IT
Rook Cliffs. IIT
Rabbit Mountain, CO
Book CHffs. CO
Cathedral Bluffs, CO
Lat
(°tl)
3R°27'
3B°23'
3R°41'
3R-41'
38°25'
3«°ft7'
36»4'
36°ir
36°24'
35-50'
35-21'
35°24'
36°3'
3R°19'
37-48'
3R°10'
3R-38'
39°07'
37-51'
37°36'
37°03'
37-40'
37-42'
38-14'
37°56 '
31-iR1
3R-07'
37°5R'
3fl°21 '
3R°19'
3R°17'
40-17'
40-33'
39-/I1'
39°53'
39-36'
4n°08'
Long Distance
(-H) (km)
109°45'
10P°16'
110°02'
110-38'
lll-Zfl1
110°4R'
112°101
U2°R'
113-7'
112-6'
111°41'
1H053'
m-sr
no-ir
110-35'
110-4H'
110°43'
110°03'
109°30'
112°10'
110°54'
111°541
111054I
U1055'
112°39'
111-20'
111-11'
110°4R'
111°29'
111029.5'
111°30.5'
109-00'
110-24'
110-25'
10R-59'
ion°5R'
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)
37°16'
3fi°2R '
36°12'
36-38'
36-40'
37°in'
4P°01'
48-0?'
48-43'
48°40V
4R-27'
4R°3n'
35°30'
35°24'
35-22'
35-21'
35-20'
35°27'
36-41'
36-02'
36°37'
36°24'
36°40'
3fi°43'
36-04'
36°28'
36-06'
35-41'
35-37'
35-14'
36-05'
35-47'
35-57'
35°57'
35-14'
35-12'
35°41'
Long Distance
(-U) (kp)
lOR-291
I09°on'
10B-52'
10R-341
10R-29'
108-57'
123-73'
123-06'
122-04'
122-49'
123-39'
1,?3°30-
111-20'
111-42'
111-38'
111-41'
111017'
110°30'
110°33'
110-52'
110-57'
Iin848'
110-22'
110-28.5'
107-57'
ion-no-
100-5.?'
108-15'
108-12'
107-35'
Olfi052'
10fi°16'
106-20.5'
10fi»21'
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)
29°20'
2<)o12.
29°2fl'
29-33'
29°30'
29°39'
32-10'
31°57.5'
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'
40°17'
40°15'
40°19'
40°22'
32-00'
32°i3'
31°55'
31-31'
31-37'
32-20'
43-40'
46-28'
43-20'
43°44'
43°44'
43°5fi'
38-15'
38-35'
3R-23'
38-19'
38°28'
38-20'
3fi°47'
36°35'
36°36'
36°48'
37-00'
36-58'
36-30.5'
37'22'
36°27.5'
35"46'
36°25'
36°46'
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'
109°58'
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'
llfi«57'
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'
45°10'
45°6'
44'52'
44°22'
44°26'
44M41
39°14'
39°07'
38°56'
3R-531
3R°55'
39°04'
39°13'
39°07'
38°56'
3fl°53'
38-551
39°04'
Long HI stance
(°W) (km)
110°43'
nn°39'
110°37'
iifvsn'
6fl°lfi'
6R-151
69°04'
120°02'
119-561
119°55'
119°56'
12n°02'
120°12'
120°or
U9056'
119°55'
m-se1
I?n°o2'
120°12'
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
CO
200
CO
Q
100~
CE
h-
CO
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
T i i |—T—r~rT~r~ i i i r i i i i i i i rr~r i i i i i i~i i i i i T i i i i i i
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-
cr
o/
tn
ID
CO
200-
Q
CE
CD
CE
I—
CO
100-
0-
I II I 1 I I I I I T
I l I I I 1 I I ill I l I I I l l l l l l l l l
1 1 1 1 1 1
JJfl 5 0 ND
1978
i i i
^
1
JFMRMJJflSOND
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
O
cr
c* CE
ID
CO
Q
CH
O
cr
CO
100-
0-
T~Ii i i i i r~i r~i i r~rnr~i i i i i i i r~i i i i i i i r~"i
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 —
LU
CT
a/
200 —
CO
Q
Q 100-1
CL
I—
CO
0-
i r i i i IT i i i i i i r i r
i i
I
I I I I I I I I I I I I I I I T I I I I I
J I
1"
1
J I
I
J Jfl 3 0 N D
1978
JFMRMJJRSOND
JFMRMJJRSOND
JFMflMJJflSON
1979 1980
MONTH
1981
82/02/1B.
-------
300-
LU
CE
CT 200
CO
Q
cr
Q
o:
I—
CO
100-
0-
DINOSnUR NflTIONRL MONUMENT
MONTHLY STRNDRRD VISURL RRNGE, GEOMETRIC MERN
i i i i i i i i i i
^^
1
1
1
i
JJ9 5 0 N D
1978
JFMflMJJflSOND
JFMnMJJflSOND
1979
1980
JFMflMJJRSON
1981
MONTH
82/02/1B.
-------
400
MESn VERDE NflTIONRL PRRK
MONTHLY STflNDRRD VISURL RRNGE, GEOMETRIC MEflN
300 —
UJ
O
:Z1
cr
200-1
CO
Q
Q/
cr
100-
cr.
i—
CO
0-
J J R S 0 N D
1978
*§
JFMRMJjnSOND
I I I I I I I I T I
JFMflMJJflSOND
1
JsJ; S
JFMRMJJfiSON
1979
1980
1981
MONTH
82/02/18.
-------
400
OLYMPIC NflTIONRL PRRK
MONTHLY STRNDRRD VISURL RRNGE, GEOMETRIC MERN
T~ I I I I I I I
LU
300-
CE
Q/
0= 200
CO
Q
Q/
100-
CE
I—
CO
0-
i i i i i i
JJRS ON D
1978
i i t i i i i i i i i
JFMRMJJRSOND
JFMRMJJRSOND
^^^^
I
I
i
i
j i i i i i i
1979
1980
JFMflMJJflSON
1981
MONTH
82/02/18.
-------
WUPRTKI NRTIONRL MONUMENT
MONTHLY STRNDflRD VISURL RflNGE, GEOMETRIC MERN
IIIIIIITITII I I I I I I I I II I I I II I I I I I I I I I I I I I I
300-
UJ
c!)
cr
o/
CL 9(710 —
Q
cr
cr
\—
CO
0-
^
JL
1
Li
JJR 5 0 N D
1978
JFMRMJJRSOND
JFMRMJJflSOND
1979 1980
MONTH
JFMflMJJRSON
1981
82/02/18.
-------
NflVflJO NRTIONflL MONUMENT
MONTHLY STflNDflRD VISUHL RHNGE, GEOMETRIC MEflN
300-
Q/
en
no
CO
Q
Q/
CT.
Q
100-
or.
h-
CO
0-
I I I I I I I I I I 1 I IT T 1 I I I I II I I I I I I I I I I
i i i i i i r
J J
n s o N D j;
JF M n M JJ
n s o N D|
JFMnMJJflSOND
JFMRMJJflSON
1979
1980
1981
MONTH
82/02/18.
-------
CHRCO CRNYON NRTIONRL CULTURflL PRRK
MONTHLY STfiNDflRD VISURL RRNGE, GEOMETRIC MERN
HUU
" 300-
LU
Z?
CE
Q/
g 200 —
CO
i — i
a
g 100-
— 7
sss
1
H
^
^
JFMRMJJRSON.D
KR1
1 1 1
Fl
W
\sS
^
^
1
^
vS\s
I
1
1
JFMRMJJnSOND
1
^
I
i
«
^
^
rax
SvVS
i
1
1
1
JFMRMJJflSON
-
—
-
—
"
1978
1979 1980
MONTH
1981
32/02/18.
-------
400-
300-
LU
cr
o/
200
CO
Q
Q/
cr.
a
a:
i—
en
\m —
0—
BflNDELIER NRTIONflL MONUMENT
MONTHLY STRNDRRD VISURL RRNGE, GEOMETRIC MERN
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
J J R S 0 N D
iS
JFMRMJJRSOND
1
i
is
1
^
J F M R M J J R S 0 N D
1979 19BQ
MONTH
JFMRMJ.IflSON
1981
-------
400
WHITE SRNDS NflTIONRL MONUMENT
MONTHLY STflNDflRD VISUAL RRNGE, GEOMETRIC MEflN
n~i i i i i i i i i i i i i i i i i i i
300-
UJ
CT.
Q/
200-
CO
a
Q/
cr.
a
100 —
cr.
\—
CO
I T I I I
i
0—
II
j .r n s o N D
1978
1
S3
sss
JFMflMJJRSOND
JFMnMJJnSOND
1979
1980
JFMRMJ.IflSON
1981
MONTH
-------
CRRLSBRD CRVERNS NRTIONRL PRRK
MONTHLY STRNDRRD VI SURE RRNGE, GEOMETRIC MERN
400
300-
LU
cb
cr
o/
cr. 200
en
Q
o/
CE
Q
100--
or.
i—
CO
0
-
-
—
1
1
J J
1
i
^
n
i
^
i
s
\
0
1
1
i
N
i
1
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i i i
i i i
JF M n
i
^
\ss
^
M
^
^
iSSS
J
N"J>
Stc<
^
J
1
ill
1978
JFMRMJJflSOND
1979 1980
MONTH
JFMRMJJflSON
1981
82/02/1B.
-------
400-
300-
UJ
or.
a/
tn
200-
CO
Q
Q/
or.
Q
CE
\—
CO
100-
0-
BIG BEND NRTIONRL PflRK
MONTHLY STRNDRRD VISURL RRNGE, GEOMETRIC MERN
T r~T \ \ \ \ i \ ] \ \ \ \ \ r~i \ \ \ \ \ i \ \ r~] \ \ \ \ \ i i ] \ \ \ \ r
w
1
J J R 5 0 N D
197Q
I
1
^
JFMRMJJRSOND
JFMRMJJRSOND
1979
1980
JFMRMJJR50N
1981
MONTH
-------
400-
300
UJ
Z
or.
tn
oo
CO
200 —
Q
0^.
cr
Q
^L
or.
t—
CO
100
0-
THEODORE ROOSEVELT NRTIONRL PRRK
MONTHLY STRNDRRD VISUflL RRNGE, GEOMETRIC MEflN
i i i i i i rT"T~r~r~rr~T~r~T~i i i i ~r~r i i \~r \ \ ~\~~r \ \ \
i i i i i i
n 5 0 N 0
1978
I I I
i
1
JFMRMJJRSOND
1
I
1
JFMRMJJflSOND
1
i
we
^
1979
1980
JFMflMJJHSON
1981
MONTH
-------
NIND CnVE NflTIONflL PRRK
MONTHLY STRNDRRD VISURL RRNGE, GEOMETRIC MERN
\/.
o
cr.
o/.
300
200-
CO
}—\
(^
Q/.
100-
cr.
\—
CO
0-
.1 .J R S 0 N D
1978
i T r i ~i
i i i
JF M R
>^N^
\x
v«v
x$s
SVN
M
~i
UAX
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n
NX}
sss
^
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rn
5555
&
ssx,
R
rn
W
!^5
wr
5^i
jw
s
r~T~r~i
0 N D
r~r~r~T~
... .1. J L_
,} F M R
rn
^
^
w
M
...
ss
$5§
>S
J
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m
^
J
~~
r«
^j
R
r~
m
$$
S
r-
0
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I
1
?|
i
1
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\ — \
D
r~
1
8v>
1
i
^
!§§
J
rn
F
r~
1
1
M
^
1
1
i
R
....
1
trr
J^
M
r "
1
1
j
••
s^
h^
ss>
.J
"T" T
^
Cvv
^o
^^ ^^"^
^N
_ .. L_
fi 5 0 N
1979
1980
1981
MONTH
-------
400
300 —
LU
O
cr
Ol
o
200 —'
CO
Q
Q/
or.
Q
Z
cr
i—
CO
100-
0-
COLORRDO NRTIONRL MONUMENT
MONTHLY STRNDRRD VISURL RRNGE, GEOMETRIC MERN
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 I ! I
.1 JR S 0 N 0
1978
JFMflMJJflSOND
ss
SSS
JFMRMJJRSOND
I
i
1
1
I
i
1979 1980
MONTH
JFMRMJJflSON
1981
-------
ROCKY MT. NRTIONRL PRRK
MONTHLY STfiNDflRD VISUflL RflNGE, GEOMETRIC MEflN
400
300
UJ
cb
z
en
CTl
200-
CO
100-
cr
f—
CO
0-
I I I II T I I I 1 I I I I I I I I I
I II I I I I I II I I I I I I I I T
J J n S 0 N D
1978
JFMfiMJJflSOND
JFMRMJJRSONDJFMnMJJnSON
1979
1980
1981
MONTH
-------
400 —
300-
UJ
c
Q/
200 —
CO
Q
Q/
or.
Q
100 —
CL
f—
CO
0-
CHiRicnHun NRTIONRL MONUMENT
MONTHLY STRNDRRD VISURE RRNGE, GEOMETRIC MERN
rT~r~r i i i i i i i i i i i i i i i i i i i~r i i i i i i i i r~r
i i i i i i
J J fl S 0 N D
1978
J_J_1_JL_I_L.JLJ_1_ J—LJ-l—L.-L-L_L-i—L.l I I I
I I
D
JFMflMJJRSONDFMRMJJRSOND
1979
1980
JFMRMJJRSON
1981
MONTH
-------
400
300 —
LiJ
CE
Q/
CTi
to
200-
CO
Q
Q/
or.
Q
100
cr.
h-
CO
0-
GRnND TETON NRTIONni PRRK
MONTHLY STRNDRRD VISUflL RflNGE, GEOMETRIC MERN
i i i T i i T~T~I i r i i i r~in i r~~i i i i i i r~i i i i i i i i i i i r
I I I I L_L
J J R 3 0 N D
1978
I I I I I I I I I I i
JFMRMJJRSOND
I
JEMRMJJRSOND
i i i i
1979
1980
JFMRMJJRSON
1981
MONTH
-------
p-
SHEhfNDORH NRTIONflL PHRK
MONTHLY STRNDRRD VISURL RRNGE, GEOMETRIC MERN
400
LU
300
cr
Q/
_J
2 0= 200 H
CO
Q
Q/
CE
Q
100 —
CE
^—
CO
0-
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 I I I I I I ~r~r~T
J J R S 0 N D
1978
JFMRMJJRSOND
JFMflMJJflSOND
1979
1980
JFMRMJJflSON
1981
MONTH
-------
400
300-
LiJ
cr
Q/
Ol
CO
200-
CD
Q/
cr
100-
cr
I—
CO
0-
CRPULIN MOUNTRIN NflTIONflL MONUMENT
MONTHLY STflNDflRD VISURL RflNGE, GEOMETRIC MEflN
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 i i i i I i i I
i
J Jfl S 0 N D
1978
i i i i i i i i i i i
JFMnMJJRSOND
J_L
ss
1
JFMflMJJRSOND
1979 1980
MONTH
JFMRMJJRSON
1981
92/02/19.
-------
TflRGET 6 CHflCO CRNYON NflTIONflL CULTURRL PRRK
MONTHLY STfiNDflRD VISURL RRNGE, GEOMETRIC MEflN
tiyu
^ 300-
UJ
CC
S — '
g: 200-
co
i — i
Q
g 100-
^xr
cn
i —
CO
i i i i
i i i i
1
i
j jn s o N D
1 1 1
1 1 1
1
1
§§§
^
^
^
PI
ss
^
^
...
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||
JFMRMJjnSOND
ill i i i i i i iii
i i i
•
i
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s'sV
1
•- \ •
^v
<^
; i
i
JFMnMJJnSON
—
—
137 B
1979
1980
1981
MONTH
-------
DEflTH VRLLEY NRTIONRL MONUMENT
MONTHLY STRNDRRD VISUflL RRNGE, GEOMETRIC MERN
<4UU
^1
" 300-
UJ
rr
_l
g: 200-
co
i — i
>>
Q/
g 100-
(X
I—-
CO
1 1 1 1 1 1
1 1 1 1 1 1
J JR S 0 N D
i i i i i i i i i i i
i i i i i i i i i i t
JFMRMJJRSOND
i i i i i i i i i i i i i i i i i i i i
1
I
1
^
^
^5
j\v
^
^
y^
\s\
^
^
S§
^
^
I
1
1
1
JFMRMJJRSOND
I
H
i
1
1
I
KTW
^CTK
^
^
^
^
P
^
^
1
1
i
JFMflMJJRSON
—
—
-
—
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—
cn
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 (%)
------- |