NCAR Airborne Instrumentation Inventory

1. INSTRUMENT IDENTIFICATION

Instrument Designation:
Fast Isoprene Sensor

Instrument Acronym:
FIS

Instrument Measurements:

a) Trace Gas
Isoprene in ambient air

b) Cloud Physics/Aerosol


c) Radiation/Optical/Electrical


d) Additional Capabilities


Resource Person/Developer:
Name: Alan Hills
Affiliation: NCAR
Phone: (303) 497-1890
Email: hills@ucar.edu

Principle of Measurement:
gas phase chemiluminescence with ozone
In situ

In situ/Remote/Flux Measurement:
in-situ

2. INSTRUMENT APPLICATION

Scientific questions to be answered:
Used to quantitate biogenic isoprene flux and for ambient measurements. The information is used in atmospheric biogenic flux models. Isoprene is the dominant biogenic reactive trace gas. Isoprene emissions are directly linked to tropospheric ozone pollution in the Southeastern U.S.

Field projects in which the instrument has been used:
NARSTO (1996); EXPRESSO (1997); PROPHET (1998 - present)

Selected publications describing the instrument, applications and field project results:
Alan J. Hills and Patrick R. Zimmerman, Isoprene Measurement by Ozone-Induced Chemiluminescence, Analytical Chemistry, 1990, 62, 1055-60.
Alex B. Guenther and Alan J. Hills, Eddy covariance measurement of isoprene fluxes, J. Geophys. Res., 1998, 103, 12145-13152.

3. Instrument Deployment

Altitude:
Expected altitudes of importance would be as low as possible.
Ground level to 10,000'

Aircraft Platform:
ideal: low, slow over region sof high isoprene flux (summertime deciduous forest)

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

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

Operator Requirements:
The operator needs brief training by Hills.

Data Collection:
Serial data strem of the PIS photon counts, three 0-5 V DC analog channels for flow monitoring. Altitude and position should be included in the data file. If eddy covariance measurement, 3-D air motion must also be recorded.

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
Weight: 19 kg FIS, 18 kg ozonizer
Power: 3A @120 VAC, non-inductive
Other: vibration -no effect; RF - minimal effect

4. Instrument Performance

Linear Range:
~ 10,000

Response Time:
0.4 seconds standard (0.2 s possible)

Detection Limits:
500 pptv @1-second

Accuracy:
The greater of 100 pptv or 5% of signal

Precision:
100 pptv or 5% of signal

Limitations (such as altitude, airspeed, etc.)
Needs rezero and calibration at each altitude (15 minutes)
No airspeed dependence expected

5. Alternative Techniques

6. Status/Plans

7. Comments