J. Geomag.
Cryogenic
Air Sampling
Stratospheric
Trace
System
Gases
for Measurements
and Their
Isotopic
Geoelectr.,
48, 1145-1155,
of the Concentrations
Ratios
over
1996
of
Antarctica
Hideyuki HONOAI,Shuhji AOx12*,Takakiyo NAKAZAWA3,
Shinji MOPIMOTO2,
and Nobuyuki YAJMA1
'The Institute of Space and Astronautical Science , Sagamihara, Kanagawa 229, Japan
National Institute of Polar Research, Kaga 1-9-10, Itabashi, Tokyo 173, Japan
3Centerfor Atmospheric and Oceanic Studies , Faculty of Science, Tohoku University, Sendai 980-77, Japan
(Received May 16, 1995; Revised August 24, 1995; Accepted October 7, 1995)
In order to measure the concentrations of trace gases such as C02, CH4, N20 and halocarbons and
the isotopic ratios of 513C, 5180 and A14Cof CO2 in the stratosphere over Antarctica in January 1998,
a balloon-borne cryogenic air sampling system was developed on the basis of the sampler which has used
for the collection of stratospheric air over Japan since 1985. The sampler developed in this study is
capable of collecting air samples with volumes of 20-30 lsTp at 12 height levels. Special attention was
paid to the sampler so that the collection of a large amount of the stratospheric air can be completed in
a short time, which is crucial for recovering the sampler near the station using a helicopter. In addition,
the samplerwas designed to land on the sea or the ice field safely. W e also simulated the flight trajectories
ofthe sampler using the wind data observed at Syowa Station (69'00'S, 39'35'E), Antarctica. The results
suggested that the sampler may land within approximately 150 km from the station, if air sampling is
made in the summer season. Indeed, the trajectories, thus predicted, were confirmed to be valid by
experiments made using a rubber balloon at Syowa Station on January 21 and February 6, 1995.
1. Introduction
The concentrations of atmospheric greenhouse gases such as C02, CH4 and N20 have been substantially increasing due to human activities since the industrial revolution, and a global climate change
is likely to occur in the near future. In addition, stratospheric ozone has decreased due to a release of
halocarbons such as CFCs for the last 10 years or more, and the strength of ultraviolet rays reaching to the
ground surface may has increased. One of the scientific themes important for these atmospheric
environment problems is to elucidate the behavior of the gases related to the respective phenomena.
Since Antarctica is fairly free from human activities and far away from vegetated land, this region
is expected to be suitable for monitoring background levels of atmospheric minor constituents. Indeed,
systematic measurements of their concentrations are currently in process at several sites in the Antarctic
region and high quality data of the concentrations have been accumulated (Nakazawa et al., 1991; Aoki
et al., 1992; Boden et al., 1994). However, the interpretation of observed variations of the concentrations
of greenhouse gases is still insufficient (Murayama et al.,1995). The fact that remarkable depletion of the
stratospheric ozone occurred over a wide area of Antarctica in early austral summer was observed for the
first time in early 1980's over Antarctica (Farman et al., 1985; Stolarski et al., 1986). This phenomenon,
which is known as "ozone hole", becomes sever year by year, although the production of specific CFCs
have been reduced for the last several years, targeting its termination in 1995. For a better understanding
of these problems, it is important to elucidate the transport processes of the related gases from other areas
such as the northern hemisphere to the Antarctic, which are not yet well understood. Knowledge of
-Present
affiliation;
Center for Atmospheric
and Oceanic
Studies , Faculty of Science, Tohoku University,
Japan.
1145
Sendai 980-77;
1146
H. HONDA et a/,
variations of greenhouse gases, their isotopic ratios and halocarbons in the stratosphere over Antarctica
is indispensable for this purpose.
Cryogenic air sampling with subsequent laboratory analysis is one of the most promising methods
to measure the concentrations of stratospheric minor constituents and their isotopic ratios precisely, since
a large amount of sample air can be collected even under low pressures and many precise analyzers can
be used.
In order to collect stratospheric air samples over Japan, a balloon-borne cryogenic whole air sampling
system was developed by aplanetary atmosphere research group ofthe Institute of Space and Astronautical
Science (ISAS) in 1985 (Honda, 1990), and then it has been launched once a year at Sanriku Balloon
Center (SBC; 39°N, 142°E) of ISAS. From the results of analyses of air samples thus collected, vertical
profiles of C02, CH4, N20, CO, halocarbons such as CFC-11, CFC-12, CFC-113, CH3CC13and CC14and
613C,8180 and A14Cof C02, as well as their seasonal, infra-annual, inter-annual and secular changes were
clearly found, demonstrating that the system was operated quite well as a whole (Itoh et al., 1989; Game,
et al., 1989, 1995; Nakamura et al., 1992, 1994; Nakazawa et al., 1992, 1995).
In order to examine the transport processes of atmospheric minor constituents to the Antarctic, the
National Institute of Polar Research (NIPR) plans to collect stratospheric air samples using the cryogenic
sampler on board a balloon over Syowa Station (69°00' S, 39°35' E), Antarctica in January 1998, in
cooperation with ISAS (Yamanouchi et al., 1993). Air samples collected will be returned to Japan in 3
months after their collection, and then analyzed with high precision for the concentrations of greenhouse
gases and halocarbons and the isotopic ratios of CO2 and CH4.
In this paper, we describe the cryogenic air sampling system developed for the collection of
stratospheric air over the Antarctic, especially in terms of its structure and function, air sampling
procedures and deterioration risk of air samples during their storage in sample cylinders. The results of
inspection of our balloon technique to be employed at Syowa Station are also presented.
2. Cryogenic
Air Sampling
System
2.1 Structure of air sampler
Figure I shows a block diagram of the balloon-borne cryogenic air sampler developed for the
collection of stratospheric air samples over Antarctica. The sampler consisted mainly of a liquid helium
dewar made of FRP, 12 stainless-steel sample cylinders, 14 motor-driven metal-to-metal seal valves, a
sample-inlet-line system, an exhaust system for gaseous helium evaporated in the dewar, an electronic unit
for controlling the whole operation of the sampler and a telemetry and telecommand system. All these
components were housed in a pressure-tight aluminum chamber (gondola) with an inner pressure of 1 x
105Pa to avoid contamination of air samples by gases released from them, as well as to prevent them from
an intrusion of sea water when the sampler lands on the sea. The volume of each sample cylinder was
approximately 760 ml and its inner wall was electrically polished. The motor-driven valve was attached
to each sample cylinder, and the other end of the valve was connected to the sample intake through the
manifold of which inner wall was also electrically polished. Air samples are introduced into the cylinders
through a 5 m bellows tube, of which one end was located 4 m below the bottom of the gondola to avoid
possible contamination from the sampler. Helium gas evaporated in the dewar is released outside of the
gondola through two exhaust lines with solenoid valves to maintain the pressure in the dewar constant,
one having a large conductance and the other a small conductance. All parts were made of stainless steel
and connected to each other by welding under highly clean conditions or with metal gaskets. After
assembly, the leakage of the system was confirmed to be less than 1 x 10 10Pa m3/sec by a mass spectrometer leak detector, and all tubing including the sample cylinders were evacuated to 1x 10-10Pa at room
temperatures by a turbomolecular pump for one week, at 110°C for 24 hours and then at room temperatures
for longer than one month to make their insides clean.
Information about location and height of the balloon, as well as the data such as temperatures and
pressures of the ambient air, temperatures in the gondola, an amount of liquid helium, pressures in the
Cryogenic
Air Sampling System for Measurements
of the Concentrations
Telemetry and
Telecommand
System
Control
Auxiliary
Sample Intel
of Stratospheric
Trace Gases
1147
Unit
Manifold
Solenoid
i Valve
.....ICI
,......
M
Exhaust for
Gaseous He
Pleasure
senate
Motor-Driven
Valve
1
2
12
Liq. He
Level Sensor
Sample
cylinder
Liq. He Dewar
Aluminum
Heater
Chamber
Sample Inlet
Fig. 1. Schematic diagram of the cryogenic air sampler developed formeasurements
ratios in the Antarctic.
of stratospheric
trace gases and their isotopic
dewar and the status of the valve operation, are always transferred to the ground station through the
telemetry system onboard the sampler, to monitor the operation of the system in real time.
Considering that the means of recovering the sampler is rather limited in the Antarctic, it is necessary
to land the sampler as near the station as possible. To minimize contamination from the balloon, air
samples will be collected during the descend of the balloon. It is necessary to descend the balloon with
relatively high speeds, since the sampler will be suspended only about 10-15 m below the balloon, which
makes the launch and recovery of the sampler easy. To realize these requirements, fast collection of air
samples is indispensable. Therefore, a new valve with a large conductance was designed to employ as an
inlet valve situated between the manifold and the sample intake. This valve was 3 times the conductance
of that used for the previous sampler. In addition, another types of valves, of which conductance was 1.2
times as large as those of the cylinders for low altitudes, were also employed for 4 cylinders to be used
for air sampling at high altitudes.
Air sampling rates for the sampler developed here were examined experimentally by changing the
pressure at the external intake. The procedures used were same as those employed by Honda et al. (1987).
The results thus obtained are shown in Fig. 2, to compare with those for the sampler used at SBC. It is
obvious from this figure that the collection speed of air samples for the new sampler was greatly increased
by employing the new valves, as compared with that for the old one.
The cross-sectional representation ofthe sampler is given in Fig. 3. The liquid helium dewar, in which
the sample cylinders were placed, was located in a central part of the gondola, and other components such
as a command receiver, a control unit and batteries were arranged around the dewar. The space among the
1148
H. HONDA et al.
35
Altitude (kin)
25
20
15
30
10
100
a
m
a
10
y
1
10
100
Atmospheric Pressure (hPa)
Fig. 2. Relationship between air sampling rate and atmospheric pressure for two cryogenic air samplers. Dotted line represents
the results for the sampler which has been used over Japan, solid line those obtained by replacing an inlet valve situated
between the sample inlet tube and the manifold with a newly designed valve with a large conductance, and dashed line those
obtained by employing a new valve with a large conductance as a stop valve of the sample cylinder, in addition to replacement
of the inlet valve.
Table
1. Specifications
of the cryogenic
air sampling
system developed
Volume of sample cylinder
Numbers of cylinder
Material of cylinder
Valve
Maximum pressure
Sample volume
Liquid helium capacity
Gondola
760 ml
Dimension
14000 x 2200H mm
Total weight
330 kg
12
SUS304
Motor-driven
>80 kg/cm2
20-30 11171
all stainless-steel
in this study.
bellows
valve
25 1
Aluminum chamber pressurized
at I x 105 Pa
respective components was filled with stylofoam blocks and beads which serve as a shock absorber and
a thermal insulator. The connection of the tubing and the electrical wires between the inside and outside
of the gondola was made through flanges on the side of the gondola. A rupture disc was also attached to
the side of the gondola to prevent the sampler from being damaged due to an unexpected abrupt
evaporation of liquid helium in the dewar. The sample inlet tube is fixed by a hose holder until the balloon
reaches a maximum height. To protect the sampler from the shock of landing on the ice field, the gondola
was equipped with external shock absorbers at the bottom and side. The sampler is suspended from the
balloon using a rigging system with 4 stainless-steel stems, and its total weight was about 330 kg. The
specifications of the cryogenic sampling system developed in this study are summarized in Table 1.
Cryogenic
Air Sampling
System for Measurements
of the Concentrations
of Stratospheric
Trace Gases
1149
Wire Attachment
l
Exhaust
Line for
Gus eoas
He
Ste m
Motor-Driven
Valve
Manifold
f
ElectroMagnetic
Valve
Control Unit
Stylofoam
ti
Guard
Stylofoam
Beads
j
Stylofoam
)_?SShock
Absorber
Sample Inle
Line
Fig. 3. Cross-sectional
2.2
representation
of the cryogenic
sampler developed
for the collection
of stratospheric
air over Antarctica.
Air sampling-procedures
Before shipping the sampler to Syowa Station, the tubing system including the sample cylinders are
disassembled,
and then each component
is evacuated and sealed off. At the station, their evacuation
are
broken by introducing
dry nitrogen gas and the respective
components
are assembled
again. Prior to air
sampling, the sample cylinders as well as the tubing between the manifold and the sample intake are
evacuated
by the turbomolecular
pump at room temperatures
for about one week, and the day before
launch, the sample cylinders are cooled to -196°C by filling the dewar with liquid nitrogen. Six hours
before launch, liquid nitrogen is removed from the dewar and the turbomolecular
pump is disconnected
after all the valves are closed. Then, about 131 of liquid helium is introduced into the dewar to cool the
sample cylinders to -269°C. It takes about 2 hours to finish the transfer of liquid helium and another 2
hours needs to assemble the sampler as a whole as well as to check the operation of the respective
components.
An evaporation rate of liquid helium was experimentally
estimated to be approximately
0.64
1/hour. Therefore, about 11 1 of liquid helium is available when the sampler is launched.
As mentioned
before, to minimize
contamination
from the balloon, air samples are collected
at
1150
H. HONDA et al.
assigned heights during the descent of the balloon. When the balloon ascends to the maximum height of
approximately 30 km, the sample inlet tube is released from the hose holder using the telecommand to
locate its intake 4 m below the gondola. At the same time, its evacuation is broken. In this regard, to avoid
intrusion of contaminated surface air into the sample cylinders, the sample inlet tube is also evacuated
together with the sample cylinders before launch. The mechanism of sealing the inlet tube and breaking
its evacuation was newly developed for the present system; a metal cap is connected to the intake using
the metal gasket and it is removed by a hard metal edge activated by exploding gunpowder, which is easy
to operate with high reliability. Exhaust of exploded gunpowder is remained in a metal-seal bellows of
the breaking mechanism to prevent possible contamination from the sample air. If the metal cap cannot
be removed by this method, an auxiliary inlet is used.
At each assigned height, which is known by a GPS system and a barometer aboard the gondola, the
motor-driven valve attached to the sample cylinder is opened and closed to collect air sample. These
procedures are automatically performed by an onboard computer after receiving a signal given from the
ground station through the telecommand system. The valve is opened until an electric pulse generated in
proportional to the rotation of the motor is counted up to a number determined in advance, and after some
finite time passes, the valve is closed so that the number of the pulse slightly exceeds that counted for
opening it, which minimizes the leakage of sampled air with extremely high pressure when it gasifies. At
low altitudes, the valves are limited to open to between 1/2 and 3/4 of a fully opened position, to suppress
abrupt evaporation of liquid helium.
An amount of air to be sampled depends on time between opening and closing the valve, degree of
opening the valve and ambient pressure. If altitudes (or pressures) are specified for air sampling, then
conditions for collecting air samples of20-30 15TPat those levels can be determined using the experimental
results shown in Fig. 2. Indeed, as seen from Fig. 4, volumes of air samples collected actually over Japan
in 1989, 1991 and 1994 agreed fairly well with those calculated in advance by the same procedure as
above. The results given in Fig. 4 show that the collected air samples disagree slightly from the calculated
mxe:
1991
Altitude(km)
Altitude(km)
30.3
PM
34.6ME
Sample Volume (lsw)
1994
Altitud
~e(km) 34
.7 1........,
Sample Volume (law)
Fig. 4. Comparison of volumes of air samples collected actually by using the cryogenic sampler at the respective heights in the
stratosphere over Japan in 1989, 1991 and 1994 (hatched bars) with those calculated on the basis of the relationship between
air sampling rate and atmospheric pressure given by the dotted line in Fig. 2 (open bars).
Cryogenic Air Sampling
System for Measurements
of the Concentrations
of Stratospheric
Trace Gases
1151
values, especially in the lower altitudes. The cause maybe ascribed to the fact that a rotary pump was used
as an aspirator of air when the results shown in Fig. 2 were derived, while the sample cylinders cooled by
liquid helium functioned actually as a collector of stratospheric air samples (Honda et al., 1987; Honda,
1990; Nakazawa et al., 1992, 1995).
The volume of the tubing between the external intake and the sample cylinders is approximately 1.8
1. Considering the volume of the tubing, atmospheric pressures in the stratosphere and about 20-30 lsTP
ofair samples to be collected, as well as supposing the vertical concentration profiles of stratospheric trace
gases observed over Japan (Itoh et al., 1989; Nakazawa et al., 1992), the influence of air introduced into
the tubing at the preceding height is almost negligible for the measured concentration values of the
respective gases at each assigned height. In this regard, the collection of air samples is scheduled to make
every 1.5 or 2.0 km height interval over Syowa Station.
After collecting air sample at the lowest height near the tropopause, the wire between the balloon and
the gondola is cut, and during the descent of the gondola using a parachute, liquid helium left is evaporated
by supplying an electric power to a heater at the bottom of the dewar (see Fig. 1), to avoid destruction of
the sampler by abrupt evaporation of liquid helium at its landing.
2.3 Deterioration ofair sample during storage
Air samples collected at Syowa Station must be stored in the sample cylinders for the period of
approximately 3 months until they are analyzed in our laboratories in Japan. Deterioration of the air
samples during their storage in the cylinders after collection is a critical problem for determining precise
concentrations of stratospheric trace gases and their isotopic values. Therefore, to examine possible
deterioration risks of the air samples, we first measured the CO2 concentrations and values of 613Cand
S's0 of CO2 of an air-C02 standard gas stored in all the cylinders for about 2 months, using a nondispersive infrared analyzer with a precision of 0.01 ppmv and a mass spectrometer with a precision of
0.02%ofor 813Cand of 0.05%ofor 3180, respectively (Tanaka et al., 1983, 1987; Nakazawa et al., 1993a;
Morimoto, 1994). The pressures of the standard gas introduced into the cylinders were approximately 3.5
x 106Pa which are almost the same as those of the air samples to be collected at Syowa Station. From this
examination, it was found that the CO2concentration of a standard gas increased by a range of 0.3 to 0.8
ppmv with an average value of 0.5 ± 0.2 ppmv, depending on the cylinders. A similar phenomenon was
also observed for the sampler used at SBC, and we also found that the increase in the CO2 concentration
of the stored standard gas was reduced by using the cylinder repeatedly (Nakazawa et al., 1995). Since
such an increase of the CO2concentration is probably due to oxidation of residual organic matter on the
inner walls of the cylinders, the storage of the air-based standard gases in the cylinders will be continued
until the increase of the CO2 concentration becomes negligible, i.e., almost 0.1 ppmv.
The results of the above examination also showed that values of S13Cand 5180 were almost unchangeable, the observed changes being ranged between -0.041 and-0.001%o with an average of -0.003
t 0.016%ofor S13Cand between 0.087 and 0.002%owith an average of 0.016 ± 0.035%ofor SISO.
The examination ofthe deterioration ofthe air samples was also made for the CI-I4concentration. The
procedures employed were almost the same as above; an air-CH4 standard gas with known concentration
was filled in all the sample cylinders and then their CH4 concentrations were determined by using a gas
chromatography equipped with a flamed ionization detector (Aoki et al., 1992; Nakazawa et al., 1993b).
The CH4 concentrations, thus obtained, agreed well with that of the standard gas at least within our
analytical uncertainties of 3 ppbv, suggesting no appreciable differences in the CH4 concentration during
storage of air samples in the cylinders.
We are currently in process of examining the deterioration of air samples for the N2O concentration,
and the tests regarding halocarbons such as CFCs have not been performed yet. However, the results of
analyses of the stratospheric air samples collected over Japan for many years showed that measured
concentrations of these trace gases in the lowest part of the stratosphere were in close agreement with
tropospheric values obtained from our measurements with aircraft over Japan and those at the ground
surface in the northern part of Japan (Itoh et al., 1989; Nakazawa et al., 1992; our unpublished data). In
1152
13. HONDA et at.
this connection,
the troposphere,
the vertical concentration
gradients of almost all halocarbons
and N20 are very small in
reflecting the fact that strong destruction ofthese gases occurs mainly in the stratosphere,
and the cylinders
of the sampler
used at SBC were treated
by the same procedures
present system. Taking this into account, it may be expected that the concentrations
N20 are fairly stable during storage of air samples in the cylinders of our cryogenic
that we did for the
of halocarbons
sampler.
and
3. Estimation of Flight Trajectory and Landing Point of the Sampler for Measurements over Syowa
Station
We examined landing points of the cryogenic sampler expected when it is launched at Syowa Station
in the summer season, which is very important to determine whether balloon measurements can be
realized. Total weight of the air sampling system including ballast, a packed parachute, a parachute
separator and a radio beacon transmitter, was estimated to be about 410 kg. If a balloon with volume of
30,000 m3 is used to lift up this system, its ceiling altitude is calculated to be 29.2 km. Assuming a flight
with respect to height shown in Fig. 5, the trajectories of the sampler and its landing points were estimated
using wind data observed over Syowa Station. For instance, by using the wind data on December 25,1989,
it is expected that the balloon flies to the southwest after its launch and the sampler lands about 70 km away
from Syowa Station, as shown in Fig. 6. If the data on January 6, 1990 are used, the sampler is expected
to land on sea ice at a distance of about 120 km from Syowa Station. The results of the examinations with
the wind data taken in January and December of different years showed that the landing locations are in
Ltitzow-Holm Bay, the distance from Syowa Station being ranged from 50 to 150 km. In this regard, this
area is usually covered with ice even in the summer season. If this is the case, it would be easy to recover
the sampler using a helicopter.
In order to validate these predictions as well as the recovery procedures of the sampler, flight tests
with a rubber balloon were performed twice at Syowa Station on January 21 and February 6,1995. Another
purpose ofthese tests is to check a mutual communication system among Syowa Station, where the balloon
is launched, icebreaker "Shirase", from which the helicopter takes off to recover the sampler, and a
recovery corps. The balloon system used for the tests consisted of the rubber balloon and payloads such
35
30
-1 nv~
25
-2m/sec
20
-4nV sec
A
15
5mM
10
...._._.
Saliooui
Cut ."V
5
0
i
0
60
120
Time after Launch
180
240
(min)
Fig. 5. Flight control pattern of the cryogenic sampler assumed to calculate its trajectories and landing points given in Fig. 6.
Cryogenic Air Sampling
System for Measurements
of the Concentrations
Southern
of Stratospheric
Trace Gases
1153
Ocean
B
Syowa
Station
LutzowHolm Bay
A
100 km
Antarctic
Continent
200 km
40E
700
Fig. 6. Trajectories and landing points of the cryogenic sampler estimated using the flight control pattern shown in Fig. 5 and
the wind data observed over Syowa Station on December 25, 1989 (A) and January 6, 1990 (B).
Rubber Balloon
Wire Cutter with
Pressure Switch
a
Parachute
Radio
Beacon
Transmitter
Radiosonde
Fig. 7. Balloon system used for validating the predictions of the trajectories and landing points of the cryogenic sampler as well
as the recovery procedures of the sampler.
1154
H. HONDA et al.
as a radio beacon transmitter,
a radiosonde, a pressure switch, a parachute and a radar reflector, as shown
in Fig. 7. Total weight of the system was approximately
5 kg. The system ascended up to 25 and 26 Ian
for the first and second experiments,
respectively,
and then the payloads descended using the parachute.
The positions of the balloon during its flight were determined
using the radiosonde system. The payloads
landed on sea ice in Ltitzow-Holm
Bay were searched by using a direction finding system of the radio
beacon onboard the helicopter and then successfully
recovered. The landing positions of the payloads for
the two experiments
agreed quite well with those predicted
using the observed wind data over Syowa
Station: the payloads were recovered at 69°07' S and 39°02' E for the first experiment
and at 69'11' S and
39°25' E for the second experiment,
while the respective predicted positions were 69°07' S and 39'03'E
and 69°09' S and 39°25' E, the distances between the predicted and actual positions being within 5 km.
4.
Summary
In order to measure the concentrations of stratospheric trace gases and their isotopic ratios over the
Antarctica, the cryogenic air sampling system was newly developed, which is capable of collecting lowpressure samples fairly rapidly. The deterioration risks of air samples during their storage in the sample
cylinders were confirmed to be almost negligible for the CO2 and CH4 concentrations and values of 313C
and SlsO of CO2 using air-based standard gases. The results for N20 and halocarbons have not obtained
yet, but inspection of the data taken in the troposphere and stratosphere over Japan suggested that their
concentrations are stable during storage of air samples. The system developed in this study will be
launched at SBC in August 1995 to validate its performance as a whole. In this experiment, new devices
developed to simplify a system for connecting the balloon with the sampler will also be examined.
The flight experiments with a simple balloon system were made twice at Syowa Station in January
and February 1995, to confirm flight trajectories and landing points of the sampler estimated on the basis
of the observed wind data over Syowa Station. The results showed an excellent agreement between the
prediction and the observation.
After performing air sampling using a small grab-sampler with one or two sample cylinders at Syowa
Station in January 1996, the collection of stratospheric air samples with the cryogenic air sampling system
developed here will be made in December 1997 or January 1998.
The authors wish to thank the staffs of the balloon technology group of ISAS for their valuable and useful
advice on developing the balloon-borne cryogenic air sampler to be used at Syowa Station, as well as for their
preparation of equipment parts necessary for the recovery tests made at Syowa Station. They also thank the members
of the 35th and 36th JARE teams for their cooperation in performing the recovery tests at the station.
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Cryogenic
Air Sampling
System for Measurements
of the Concentrations
of Stratospheric
Trace Gases
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