United States
Environmental Protection
Agency	
                             s>"
Atmospheric Sciences         ;
Research Laboratory          ~*f.,    «
Research Triangle Park. NC 27711   / /,"-
Research and Development
EPA/600/S3-88/015 May 1988
 Project Summary

 Development  of an  Adjustable
 Buoyancy Balloon Tracer of
 Atmospheric  Motion:  Phase III.
 Refinement  of the  Operational
 Prototype  System
 B. D. Zak and E. W. Lichfield
  The adjustable buoyancy balloon
tracer  of atmospheric motion  is a
research tool designed to follow
atmospheric  flows in both  the
horizontal and the vertical, including
the weak sustained vertical motion
associated  with  meso-   and
synoptic-scale  atmospheric
disturbances. The design  goals for
the tracer balloon specify a lifetime
> 3 days, tracking range > 1000 km,
ceiling altitude > 5.5 km  (500  mb),
and capability to respond to mean
vertical flows as low as 1 cm/s. While
the tracer  has  applications
throughout  the  atmospheric
sciences, the immediate motivations
for this effort are to meet the need to
evaluate the accuracies of  air
pollution  transport  models, to
establish    source-receptor
relationships  to distances of the
order of 1000 km, and to assess the
inherent limits on the predictability of
source impacts at long distances. In
Phase I  of this project, entitled
"Systems Design and Demonstration
of Feasibility," the authors proposed
a generic design for such a system,
subjected the design to theoretical
analysis, constructed a test-bed
prototype, and conducted a series of
tests with that prototype to evaluate
the concept. In Phase  II of the
project, the authors  developed an
operational prototype designed to
meet  the desired specifications. A
limited number of test flights of the
operational  prototype  were
conducted. Flights were made using
each of the three currently available
control  algorithms:  constant
pressure,  constant  potential
temperature,  and  zero  relative
motion. Analysis of the data indicated
that, in each case, the control system
functioned properly. In Phase III of
the project, the subject of this
summary, improvements were made
in electronic design, packaging,  and
in the remote  command and data
reception system. Two test  flights
were made, and while the results
from these flights were inadequate to
demonstrate that the design goals
were met, the results were  not
inconsistent with that conclusion.

   This  Project Summary was
developed by  EPA's Atmospheric
Sciences  Research Laboratory,
Research  Triangle  Park,  NC,  to
announce key findings of the research
project that Is fully documented In a
separate report of the same title (see
Project Report ordering Information at
back).


Introduction

   The adjustable  buoyancy balloon
tracer  of  atmospheric motion is  a
physical Lagrangian tracer (PLT) - an
airborne instrumentation system  that

-------
follows the flow of air in its vicinity,  and
that  can be tracked electronically.  For
decades, researchers have sought such
a tracer to aid  in  understanding  the
dynamics  of the atmosphere: and more
recently, to cast light on long-range air
pollution: acid  deposition,  regional haze
and  oxidant episodes, and associated
ecological effects. Advances  in
microelectronics,  satellite   com-
munications,  and battery technology
have now  made a PLT system feasible.
The  present effort is motivated primarily
by   the  immediate  programmatic
requirements of the  U.S. Environmental
Protection Agency.  In  a  more  basic
sense, however,  it  addresses a  broad
underlying need for  a convenient means
of following atmospheric flows.

   PLTs are necessarily  balloon-borne
systems  and,  consequently,  must
operate  under  Federal  Aviation
Regulations Part  101: Moored Balloons,
Kites, Vlnmanned Rockets,  and
Unmanned Free Balloons. The purpose
of this regulation is  to strictly limit the
hazard  ^o air  navigation  that  such
systems might otherwise represent. FAR
101  divides balloons into two classes.
Those that offer  little hazard to  aircraft
because of their limited size, weight,  and
density are explicitly exempted from
most of the  other  stipulations  of  the
regulation. Under this provision, the U.S.
weather services,  together with  the
weather services of other nations around
the world, routinely  launch hundreds of
radiosonde  balloons  twice  daily.
Radiosondes measure the meteorological
conditions aloft  from the  surface to
beyond  20 km above  many   major
airports  and certain  other selected sites.
Balloons not satisfying  the exemption
provisions of FAR 101 are treated much
like other aircraft, and are subject to strict
regulation.

   It is  an explicit design goal that the
tracer  balloon  operate  under  the
exemption clauses  of FAR  101,  as do
radiosondes. If this  goal  were not met,
FAR 101  would severely  limit  the
usefulness of the tracer balloon.

   Because   safety  is  a  major
consideration,  certain safety features
beyond those specified by FAR 101 are
incorporated in  the tracer balloon design.
In particular, even  though the  Federal
Aviation Administration (FAA) does not
require  it, when the tracer  balloon  is
flown at  altitudes  available  to  other
aircraft, it will carry  an FAA transponder.
Consequently, the FAA will see the tracer
on radar as prominently as a commercial
airliner,  and  can  control air traffic
accordingly.

   The intended uses also provide other
tracer balloon design goals:

   • Lifetime > 3 days.
   • Tracking range > 1000 km.
   • Telemetry  of  relative  vertical  air
     motion, pressure, temperature  and
     humidity.
   • Ground system capable of handling
     several tracer balloons at a time.
   • Capable of establishing  specified
     ascent and descent  rates under
     radio command.
   • Capable of reaching altitudes up to
     5.5 km (500 mb).
   • Capable of following mean vertical
     flows  as   low as  1   cm/s  with
     acceptable fidelity.
   • Sufficiently inexpensive to permit
     use in significant numbers on  an
     expendable basis.

    The original project plan divided the
work into four phases:
   Phase I:   Systems  Design   and
            Demonstration of Feasibility.
   Phase II:  Development    of   an
            Operational Prototype.
   Phase III: Testing  and  Refinement of
            the  Operational  Prototype
            System.
   Phase IV: Addition of   Elements
            Necessary  to Create  a
            Practical Research Tool.
Phase  I was initiated in fall, 1983,  and
ran through calendar year 1984.  The
results were previously reported in the
Phase  I report which gives  the chain of
reasoning and the experimental data  that
led to  the  operational prototype design
described   here.  Phase  II  spanned
calendar year 1985. Phase III  began in
spring  of  1986  and extended through
1987.  The  US EPA  does  not  have
resources to support Phase IV.

Concept
   Balloon  systems  obey Archimedes'
Principle: A body immersed in a fluid is
buoyed up by a force equal to the weight
of the fluid  displaced. This implies that a
balloon system  will be  in  equilibrium
when the weight of the air it displaces is
equal to the weight of the system.

   Constant volume  balloon (CVB)
systems have  a unique  characteristic.
The equilibrium condition is met only at
one well-defined altitude, and  the  CVB
seeks that altitude.  If a  CVB  should I
itself above its equilibrium altitude, it
experience a net downward force due
gravity because the ambient air  is li
dense  at the higher altitude,  and
volume of air displaced is fixed.  Likewi
if a CVB should be below its  equilibrii
altitude, it  will experience a net upw.
force, since the buoyancy force excee
the gravitational  force. Thus,  CVBs te
to oscillate  around  their equilibrii
altitude,  the oscillations  driven
atmospheric  turbulence.  In atmosphe
flows  that  have zero average  vertic
velocity,  CVBs  naturally follow tl
horizontal  flow  at their  equilibria
altitude. However, in flows in which  tl
vertical component  is significant,  a C\
will not adequately follow the overall flo\

   The tracer balloon is  a modified CV
It is designed to sense its deviation fro
the mean vertical flow, and to adjust i
buoyancy to keep  its average  vertic
motion relative to the air  surrounding
near  zero.  Thus, the tracer follows bo
horizontal and vertical flows.
   The buoyancy adjustment princip
used in the tracer was first put forward b
V.E.  Lally  of the   National Center  f<
Atmospheric  Research almost 20  yeai
ago.  He proposed  a CVB with  an inn|
bladder, or ballonet,  to contain the lift ga
(helium).  The remainder of the CVB wa
to  be filled with air. A system of pump
and valves was included  to allow air to b<
pumped  in or released, respective!
increasing the  mean  density  of thi
balloon  and  thereby  decreasing  it:
equilibrium  altitude,  or  decreasing th<
mean density and  thus  increasing thf
equilibrium altitude.

   Two basic approaches to the altituds
control problem  were considered. Th<
first was to  continuously  measure th«
vertical velocity of the air  relative to the
balloon, and  to adjust the buoyancy sc
that on average, the relative  velocity ol
the air is  zero -  that  is, so  that the
balloon and the  air  move together. The
second approach is  to take advantage ol
the very  nearly adiabatic  nature o1
atmospheric  flows.  When  flows are
adiabatic,  the potential  temperature  (or
equivalent  potential  temperature  in the
presence  of liquid  water) is constant
along  each  air parcel trajectory.  In this
approach, the buoyancy is adjusted so
that the trajectory is isentropic. As long
as this condition is  met, the balloon will
move along with the air surrounding it.
   The approach to altitude control basei
on  relative vertical  air  motion is very

-------
   ect,  but  if  it were  to  be  used
Continuously  for three  days,  the air
motion measurement would have to be
extraordinarily accurate. Under most
atmospheric conditions, the approach
based on potential temperature is quite
satisfactory, but in a  layer of air in which
convective  mixing   is  taking  place,
potential temperature does not offer an
adequate guide to altitude control. Under
these conditions, the air surrounding the
balloon consists of  turbulent  flows
moving  both up  and down. The  mixing
makes the potential temperature uniform
with altitude within the convective layer.

   When convective  mixing  engulfs  a
parcel  of  air, the  main  effect is  to
disperse it and to spread  it out  in the
vertical, mixing it with air from  all the
surrounding parcels.  If a tracer balloon  is
embedded  in  an   air parcel that  is
subjected  to convective  mixing as long
as  the  balloon remains  in  the  mixed
layer, it lies within  the confines  of the
now  greatly  expanded  "parcel."  A
balloon  following the  expanding  parcel
during  convective  mixing makes less
stringent  demands  on  the  buoyancy
control system than does one following a
  arcel under stable conditions. Hence, a
 .umber of different control strategies are
satisfactory under convective conditions.

   Thus, an approach that makes use  of
different  control   algorithms  under
different meteorological  conditions will
yield the best results. On the basis of the
sensor   data,    the   on-board
microcomputer can  be programmed  to
determine which  control algorithm will be
implemented at any given time.

   The  operational  prototype currently
incorporates three  control  algorithms
selectable  by  radio command. The
control  parameters for these algorithms
are relative  vertical  displacement,
potential  temperature,  and  ambient
pressure.  In  a stable (non-convective)
atmosphere,  in  the  absence of liquid
water, the  potential  temperature  control
algorithm is most appropriate. In a stable
but saturated  atmosphere, an algorithm
yet to be  written  using  equivalent
potential  temperature would be most
effective.  In a convective atmosphere,
relative vertical  displacement becomes
the control parameter of choice. Under
convective conditions, over  reasonably
 'lat terrain, even the  constant  pressure
 jontrol  algorithm may be satisfactory.
Operational Prototype
  The operational  prototype system
consists of the balloon envelope with its
pay load and a  ground support station.
The balloon is a sphere of 2.9 m nominal
diameter (12.5 m volume)  made of 3.0
mil  bilaminated  polyester with a 1.0 mil
full-volume  polyethylene  ballonet
inside. The balloons were made  by
Raven Industries. The payloads consist
of a  buoyancy  adjustment  subsystem,
sensors,  a  microcomputer,  a telemetry
subsystem,  a  radio   command
subsystem, a cutdown device, tracking
aids, and batteries.
  An  assembly  drawing  of  the
operational  prototype is  given in  Figure
1. The inner  balloon is  attached to the
outer balloon only at the  helium fill fitting
located at the top. The bottom fitting, a
19  cm  diameter  nylon   plate, was
modified to accept  two fittings for  air
lines,  and   electrical   leads  to
accommodate  a  pressure  sensor
assembly inside the balloon.  A larger
fitting, closed  off in flight, was also
installed  on the bottom  plate to permit
rapid inflation and deflation.
   The buoyancy adjustment subsystem
makes use of the same type of pumps
and valves used in the Phase I prototype.
The pumpdown  speed - the rate at which
the equilibrium altitude can be lowered -
is determined  both  by the  temperature
lapse rate  and by  the  pressure  head
against which the pumps must work, the
*superpressure."  With   30  mb
superpressure,  in  a   standard
atmosphere, the calculated  pumpdown
speed with the three  pumps used  is
about 15 cm/s.  The  valves permit a rise
in equilibrium altitude  about three times
faster.
   The sensor  subsystem  consists of
three elements. The first is  an  aspirated
sensor assembly that measures ambient
pressure, temperature, and humidity. It is
a modified Atmospheric Instrumentation
Research  Inc. prototype  digital
radiosonde. The assembly outputs data
in ASCII  format. The transmitter normally
in place has been  deleted,  and the
assembly  has  been  housed  in  a
styrofoam package normally used for a
tethersonde, rather  than a  radiosonde.
The  tethersonde   package  makes
provision for aspiration.
   The  second  element is a second
modified digital AIR  sensor  assembly
mounted on the inside of the baseplate
to report pressure and temperature within
the balloon. No aspiration is provided for
this unit.
   The third  element  is the  vertical
anemometer.  It  makes  use  of  a stock
22.9  cm  (9  in)  diameter  expanded
styrofoam Gill  propeller from R.  M.
Young Inc.,  and  a  slightly modified
Spaulding Instruments Cl rotation sensor.
It has a starting speed under 2 cm/s, and
a  measurement threshold of  under 3
cm/s. This  starting speed and  low
velocity  performance  should  allow
accurate relative  vertical  velocity
measurements averaged over minutes to
be made  down to 1 cm/s or less.
   The heart of the control system  is an
Intel  8052AH  BASIC microcomputer. For
Phase III, the memory was  increased
from  4   K bytes  of random   access
memory   (RAM)  and  4 K  bytes of
programmable  read  only memory
(PROM) to 16 K bytes each of RAM and
PROM. The control program is written in
BASIC   and  is  entered  into   the
microcomputer from a  terminal.  To
provide reliable polling  of the sensor
values,     a    Universal   Syn-
chronous/Asynchronous  Receive   and
Transmit  chip (USART) was added, along
with  a machine language subroutine to
service the USART. A block diagram of
the payload system is shown in Figure 2.
   Both   telemetry  and  tracking  are
handled  through  the Argos satellite-
based data  collection and  platform
location   system.  The  Argos platform
transmitter  terminal was  made  by
Telonics,  of  Mesa,  AZ. It is uniquely
compatible  with  the  flight  control
microcomputer. It is controlled by ASCII
input commands.

   The radio command  receiver   was
designed  and built for  application  by
Sandia National Laboratories by Hock
Engineering  of Boulder, Colorado.  It
operates on 13.8035 MHz, a frequency to
which Sandia has access. It  has a one
microvolt sensitivity.  The  command
receiver antenna is a quarter wavelength
wire which was attached to the skin of the
outer  balloon, rather than left  to  trail
below.
   Commands are  electronically  encoded
at the ground station transmitter,  and
decoded  at the receiver. In Phase II, the
encoder/decoder  circuit  pair were
commercially available  components
designed   for  use  in television  remote
control systems. This system was found
to be highly vulnerable to  electronic
noise. The  command  system   was

-------
                       Figure 1.    Assembly drawing of Phase III Tracer Balloon. A. Top fitting with cutdown device
                                   and helium fill line. B. Vertical anemometer. C. Cutdown timer. D. Recovery beacon
                                   (not flown on flight 2). E. External sensor assembly. F. Radar comer reflector.
                                   G. Radio command receiver. H. Independent airsonde. I. Internal sensor assembly.
                                   J. Bottom plate with valves and servo. K. Pump box. L Main electronics package.
                                   M. Argos antenna. N. FAA transponder package (not flown in flight 1).
changed to  be more  noise  resistant
through  the  use   of   dual  tone
multifrequency coding. The same pair of
tones  must  be  present  on multiple
interrogations for the  command  to  be
considered valid.

   The  commands currently  available
are:
   - activate cutdown
   - reset cutdown timer
   - turn on pumps (to lower altitude)
   - open valve (to increase altitude)
   - initiate control in pressure mode
   - initiate  control  in  potential
     temperature mode
   - initiate control  in relative vertical
     motion mode
   - increment current value of control
     parameter
   - decrement current value of control
     parameter
The encoder/decoder pair is capable  of
incorporating many more commands with
minimal changes.

   A cutdown  device at  the top of the
balloon  releases the helium lift gas on
command.  The rate  of venting is  such
that descent  takes  place at a  safe
velocity.  A cutdown  timer  automatically
actuates the  cutdown  device after  a
preselected period. However,  the  timer
can be reset to zero by radio commanc
In normal  operation,  the timer  rese
command is sent at frequent intervals. A
long as those commands are received <.
intervals  not exceeding the preselectei
period, automatic  cutdown is avoided. I1
on the other hand,  radio communicatioi
with the tracer  is  lost  for  a  perioi
exceeding  that  which  has   bee
preselected,  the tracer is  automatical!
removed from the sky. This arrangemer
avoids  the  possibility  of the  trace
becoming a  derelict  in the event tha
radio communication is lost.

    For  both test flights,  a corner-typl
radar reflector  was  flown, and on  thi
second  flight, a  FAA  transponder witl

-------
                     System Block
                       Diagram
                                                                         +5v
External
Sensor
Assembly

Internal
Sensor
Assembly
•^,
^
-T»

USART
	 ^

?
Computer
                                             +5v
                          Wake-Up
^__
Voltage
Regulator
^



Lithium
Battery
      +5v
  Figure 2.    Block diagram of Phase III Operational Prototype Pay load.
                                                                                                                +Sv
encoding altimeter was flown.  Thus far,
no night flights  have been conducted,
hence a  strobe light  has  not been
needed.

   The batteries, lithium thionyl chloride
units in AA, C, and D cell sizes procured
from  Altus Inc., are reported  to  have
excellent low temperature characteristics.
This property will be necessary to meet
the 5.5 km (500 mb) altitude design goal.
At this altitude, low temperatures will be
encountered.  Preliminary tests  with the
batteries have been conducted down to
-18  C.
   The  command and  data reception
system  used in Phase III consists of a
Handar Argos downlink  receiver  and
decoder, an  IBM  compatible  PC (NEC
APCIII),  a  command  encoder  and
interface package, an ICOM model 745
transceiver with  FM option  and  an
antenna coupler. A block diagram of the
system is shown in Figure 3. For the first
test flight, the system was mounted in ia
5-m  Airstream  trailer.  For the  second
flight, planned  to  be much longer, the
system  was mounted in  the Sandia de
Havilland  Twin  Otter  instrumented
aircraft. The PC converts the Argos data
stream  from hexadecimal to  decimal
form,  formats it, provides a hard  copy
listing  of the  results,  and  stores the
results on the NEC internal hard disk.

   Inflation  of the Tracer Balloon  in the
field without shelter  would  be  very
difficult.  For Phase  III, a conventional
hangar at a conveniently located airport
was used.

Results and  Discussion
   The  Phase  III  test  flights  were
launched from Sandia  Air Park, a small
airport about 40 km east of Albuquerque
near the community of Edgewood. This
site is  east of the  Sandia and Manzano
Mountains,  so flights  made under the
influence of the usual westerly  winds
would  not immediately encounter rough
terrain.

   The first flight  was  planned for  an
altitude of about 300 m. To aid recovery
and tracking, a  Telonics  radio beacon
designed for animal tracking was flown.
   Liftoff of flight 1, shown in  Figure  4,
occurred  at 10:49 a.m. on  August 13,
1987. Winds at the surface at launch time
were estimated to be  gusting to 15 kts.
For this flight, the Argos antenna on the
balloon was a high gain device designed
by  NCAR for  use on  high  altitude
balloons.  The  radiation  pattern  of  this
antenna is primarily  vertical, thus making
reception at the ground from a system  at
low altitude to the ground difficult. With
the high winds encountered in  this  first
flight, the Tracer Balloon was carried out
of range  of the  data reception  within a
quarter of an  hour. Data  from  the  AIR
sonde attached to the skin of the balloon
was received for about a half hour, until a
parked aircraft came between the ground
antenna and the  Tracer Balloon. The AIR
signal  was  reacquired  just  before
touchdown, but by that time the Tracer
was  no longer  in  sight.  The  Tracer
Balloon appears to  have  responded  to
commands throughout the flight. It  was
decided, given  the  loss of reception  of
the Argos  data  at the ground station,  to
allow the  automatic cutdown timer  to
terminate the flight. Touchdown occurred

-------
                                 Ground
                                 Station
                               Components
                                                          H.F.
                                                          Antenna
                                            ARGOS
                                            Antenna
                                          (401.65 MHz)
                                         \ Keyboard]
                       Figure 3.    Block diagram ol Phase III command and data reception system.
14 km of the launch site, at about 11:59
a.m.

   The second flight was planned for an
altitude of about 1000 m. The addition of
the Terra FAA transponder added 1.8 kg
to the balloon  payload.  To  provide
adequate  lift,  a  zero  pressure balloon
was attached to the top of the adjustable
buoyancy balloon.  In this way, ignoring
thermal heating of the balloon by solar
radiation, the weight of the transponder is
balanced by the lift of the zero pressure
balloon independent of altitude.

   Launch  of the second  test  flight
occurred at 1:29 p.m.  of January  13,
1988. About  12  minutes into the flight,
the balloon  had risen  to about  110 m
above ground and was about 1.5  km
from  the launch site.  At that  level,  the
Tracer encountered a violent wind shear.
Below this level, the winds had been light
and from the southeast. Above  110 m
altitude, winds were much stronger  and
directly out  of the west. The shear  was
so  violent that the rigging holding  the
main  electronics package  and  the
transponder to the main balloon gave
way.  It is speculated that  the coupled
oscillations induced by  the  shear in the
complicated tandem balloon system may
have  been  responsible  for whiplash of
the payload packages resulting in high
g-forces.

   The tandem balloon system, released
from  much of its burden, began to  rise
rapidly. With the loss of the electronics
payload,  automated control,  remote
command control,  and the Argos  data
link were lost. The AIR sonde velcroed to
the balloon skin remained and continued
to send  data. The  main and  auxiliary
balloons remained together and rose to a
maximum  altitude  of about  5200  m
(17,100  ft MSL), and  then came slowly
back down. The chase aircraft caught up
with the balloons as they passed through
3800  m  on the way down. From the
aircraft, there was no visual evidence of
catastrophic  failure  of  either  balloon
envelope. Rather it appears that the thin
membrane which is part of the cutdown
device on the main  balloon served  as  a
pressure relief device and blew out when
the superpressure exceeded the  strength
of the  membrane  or the membrane
holder. It is  known from  the  cutdown
timer  setting that the cutdown  device
would not have fired before the balloon
began descending. The aircraft followed
the tandem  balloon system  until   it
touched down about 16  km west of the
village of Anton  Chico, NM at about 2:50
p.m., about 83 km from the launch site.

Recommendations and
Conclusions
   Problems  with damage to the  inner
ballonet  on  installation in the outer
balloon during the manufacturing process
need to be overcome. Leaks at the top
and bottom fixtures  need   to be
eliminated by improved design. Failure of
the circular top seam joining the  gore
structure to the  top mylar piece must be
eliminated by proper reinforcement at th<
factory.  These  problems  must  bi
eliminated if  the  technology  is  to  set
routine use.

    Clearly the rigging  of  the  payloa<
needs to  be improved to assure that it i:
not possible to  lose  the  payload  ii
turbulence or wind shear. It  is noted tha
the packages velcroed to the skin of th<
balloon appear to have survived withou
difficulty.  Attaching all of the packages ii
this way may be a satisfactory solution.

    The  control  software still does no
contain provision for  either  an "effectivi
potential  temperature" control algorithm
or provision  for  self-selection  of  th<
control  algorithm.  Both  should  b<
implemented.

    The  command and data receptioi
system currently makes use of a Handa
Argos  receiver  and  decoder. It  i
obsolete, and in a  cold environment
does not function properly.  It should b
replaced. For long Tracer Balloon flight;
use of a  chase aircraft will prove to b
very convenient - provided  comman
and data reception system  are availabl
both on the ground  and in the aircraf
This would require a second comman
and data  reception system.

    At the end of the Phase I and Phas
II reports, the authors concluded that a
adjustable  buoyancy tracer  balloo
meeting  the design goals  is  bot
technically  and  economically feasibk

-------
 Figure 4.    Tracer Balloon shortly after liftoff of flight 1. which occurred at 10:49 a.m. on
             August 13, 1987.
Phase III continued  to confirm that
conclusion.  It  remains  to  be
demonstrated, however,  that  those
design goals have in fact been fully met.
Nevertheless, the  Tracer Balloon system
is already a useful atmospheric research
tool.

-------
    8. D. Zak is with Sand/a National Laboratories, Albuquerque, NM 87185 and A.
      W. Uchfield is with Spectra Research Institute, Albuquerque, NM 87109.
    J. S. Irwln and R. G. Lamb are the EPA Project Officers (see below).
    The complete report, entitled "Development of an Adjustable Buoyancy Balloon
      Tracer of Atmospheric Motion: Phase  III. Refinement of the Operational
      Prototype System," (Order No.  PB 88-190 764/AS; Cost: $32.95, subject to
      change) will be available only from:
              National Technical Information Service
              5285 Port Royal Road
              Springfield, VA 22161
              Telephone:   703-487-4650
    The EPA Project Officers  can be contacted at:
              Atmospheric Sciences Research Laboratory
              U.S. Environmental Protection Agency
              Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
AUG;l'88
                 rn  q
                 ,. U  .-J
Official Business
Penalty for Private Use $300

EPA/600/S3-88/015
                 0000329   PS


-------