NCAR Airborne Instrumentation Inventory

1. INSTRUMENT IDENTIFICATION

Instrument Designation:
Fast DMS (dimethyl sulfide) Sensor

Instrument Acronym:
Fast DMS Sensor

Instrument Measurements:

a) Trace Gas
DMS in ambient air

b) Cloud Physics/Aerosol


c) Radiation/Optical/Electrical


d) Additional Capabilities


Resource Person/Developer:
Name: Alan Hills and Don Lenschow
Affiliation: NCAR
Phone: (303) 497-8970
Email: hills@ucar.edu, lenschow@ucar.edu

Principle of Measurement:
chemiluminescence with F2 (molecular fluorine)

In situ/Remote/Flux Measurement:
in situ

2. INSTRUMENT APPLICATION

Scientific questions to be answered:
Used to measure DMS concentrations and fluxes in the marine troposphere. The information will be used in atmospheric simulations related to global warming since it is believed that DMS is an important precursor to CCN. We also predict that eddy flux measurement can be used to calculate highly accurate cloud entrainment velocities.

Field projects in which the instrument has been used:
none, new instrument

Publications describing the instrument, applications and field project results:
Alan J. Hills, John W. Birks and Donald H. Lenschow, Fast Dimethyl Sulfide (DMS) Measurement by Fluorine-Induced Chemiluminescence, Analytical Chemistry, 1998, 70, 1735-1742.

3. Instrument Deployment

Altitude:
Altitudes of importance would be 0-25,000'

Aircraft Platform:
large, spacious

Inlet Configuration/Location:
Next to a high flow duct, i.e., to support eddy correlation.
Parallel vent duct also needed.

Calibration/Cross Calibration:
Calibration via dynamic dilution system (built-in)
Cross calibration via comparison to GC or MS analyzed samples.

Operator Requirements:
Alan Hills is the sole operator to present.

Data Collection:
RS-232 photon counter and 0-5 V pressure and flow control outputs.

Post-flight Data Validation, Processing, Hours per Flight Hour etc.
Quick-look concentration data, 2 hours/flight.
Quick-look eddy correlation flux data, 4 hours/flight.
Data into formal archive, 10 hours/flight.

Physical Characteristics:
Dimensions: 1 full height rack needed (pump dominates space, size and power requirements)
Weight: sensor 30 kg, vacuum pump 50 kg,
Power: sensor 2A @120 VAC, non-inductive; pump 20A @120 VAC, inductive (240 VAC is an option)

4. Instrument Performance

Linear Range:
10,000

Response Time:
0.1 seconds

Detection Limits:
12 pptv @ 1-second

Accuracy:
uncertainty: the greater of 20 pptv or 7% of signal

Precision:
20 pptv, 5% of signal

Limitations (such as altitude, airspeed, etc.)
None

5. Alternative Techniques

6. Status/Plans

7. Comments