NCAR Airborne Instrumentation Inventory

1. INSTRUMENT IDENTIFICATION

Instrument Designation:
Whole Air Sampler

Instrument Acronym:
WAS

Instrument Measurements:

a) Trace Gas
WAS collects samples for a range of trace gases including CFCs, HCFCs, HFCs, Methane, C2-C5 alkanes, C1 and C2 chlorinated compounds, Halons, methyl halides, Bromochloromethanes, alkyl nitrates, etc.

b) Cloud Physics/Aerosol


c) Radiation/Optical/Electrical


d) Additional Capabilities


Resource Person/Developer:
Name: Elliot Atlas & Stephen Donnelly
Affiliation: ACD
Phone: (303) 497-1425 & 497-1409
Email: atlas@ucar.edu & donnelly@ucar.edu

Principle of Measurement:
Trace gases are collected in stainless steel canisters for analysis by GC/FID and GC/MS techniques.

In situ/Remote/Flux Measurement:

2. INSTRUMENT APPLICATION

Scientific questions to be answered:
Halogen Budgets of the Stratosphere
Mixing Rates and Transport Processes in the UT/LS
Tracer Studies in the UT/LS
Relationship between biogenic/anthropogenic VOC emissions and ozone production in the troposphere.

Field projects in which the instrument has been used:
Airborne Antarctic Ozone Experiment (AAOE) 1987
Airborne Arctic Stratospheric Experiment (AASE I and II) 1989 and 1991/92
Stratospheric Tracer of Atmospheric Transport (STRAT) 1995/96
Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) 1997
Atmospheric Chemistry of Combustion Emission Near the Tropopause (ACCENT) 1999
Southern Oxidant Study (SOS) 1999
Sage III Ozone Loss and Validation Experiment (SOLVE) 1999/2000
Texas Air Quality Study (TexAQS 2000) 2000

Publications describing the instrument, applications and field project results:
Heidt, L.E., J.F. Vedder, W.H. Pollock, R.A. Lueb, and B.E. Henry, Trace gases in the atarctic atmosphere, JGR, 94, 11,599-11,611, 1989.

Schauffler, S.M., E.L. Atlas, D.R. Blake, F. Flocke, R.A. Lueb, J.M. Lee-Taylor, V. Stroud, W. Travicek, Distributions of brominated organic compounds in the troposphere and jower stratosphere, JGR, 104, 21,513-21,535, 1999.

Flocke, F., E. Atlas, S. Madronich, S.M. Schauffler, K. Aikin, J.J. Margitan, and T.P. Bui, Observations of methyl nitrate in the lower stratosphere during STRAT: Implications for its gas phase production mechanisms, GRL, 25, 1891-1894, 1998.

3. Instrument Deployment

Altitude:
0-20 km

Aircraft Platform:
NASA ER-2
NASA WB-57
NOAA WP-3D Orion
NCAR L-188C Electra
(possible on DC-8, C-130 and others)

Inlet Configuration/Location:
As appropriate for each aircraft

Calibration/Cross Calibration:
Trace gas standards prepared and calibrated in-house
Trace gas mixtures prepared commercially and calibrated in-house
NIST standard gas mixtures
Interlaboratory Comparisons (NOAA and others)

Operator Requirements:
Automatic operation

Data Collection:
self

Post-flight Data Validation, Processing, Hours per Flight Hour etc.
All analysis is post-flight with approx 10 - 15 samples analyzed per day per instrument

Physical Characteristics:
Dimensions: Different configurations possible
Weight: 175 - 300 lbs, depending on configuration and number of canisters
Power: 400 Hz AC and 28 VDC
Other:

4. Instrument Performance

Linear Range:
N/A

Response Time:
Canister fill times are altitude dependent. approx 8 secs at altitudes <30,000 ft, to 240 secs at altitudes >20 km.

Detection Limits:
Typical detection limits are in the .1 pptv range for GC/MS analysis, and <1 - 2 pptv for FID analysis

Accuracy:
Estimated at approximately 10%

Precision:
Estimated at approximately 2 - 5%; compound and concentration dependent.

Limitations (such as altitude, airspeed, etc.)

5. Alternative Techniques

6.Status/Plans

7. Comments