NCAR Airborne Instrumentation Inventory

1. INSTRUMENT IDENTIFICATION

Instrument Designation:
Scanning Actinic Flux Spectroradiometers

Instrument Acronym:
SAFS

Instrument Measurements:

a) Trace Gas


b) Cloud Physics/Aerosol


c) Radiation/Optical/Electrical
Total actinic radiation 280-420 nm

d) Additional Capabilities
Calculation of photolysis frequencies for 12 molecular species. Longer wavelength scans possible.

Resource Person/Developer:
Name: Rick Shetter
Affiliation:NCAR/ACD
Phone:303-497-1480
Email:shetter@ucar.edu

Principle of Measurement:
True hemispherical collection of solar radiation with wavelength dependent output.

In situ/Remote/Flux Measurement:
In situ

2. INSTRUMENT APPLICATION

Scientific questions to be answered:
Down-welling and up-welling actinic flux can be used for radiation balance experiments and radiative transfer studies. Photolysis frequencies of 12 molecules can be calculated from the actinic flux for use in photochemical modeling.

Field projects in which the instrument has been used:
NASA PEM-Tropics A, NASA SONEX, NASA PEM-Tropics B.

Publications describing the instrument, applications and field project results:
Photolysis frequency measurements using actinic flux spectroradiometry during the PEM-Tropics Mission: Instrumentation description and some results. Shetter and Muller,JGR (in press).

3. Instrument Deployment

Altitude:
All

Aircraft Platform:
NASA DC-8, NASA P3-B

Inlet Configuration/Location:
Optical collector and shadow ring at centerline Zenith and Nadir ports. Zenith location as far from the tail as possible. No other probes should be in the optical field of view.

Calibration/Cross Calibration:
Calibrations with NIST traceable irradiance sources. Cross calibrations with chemical actinometers.

Operator Requirements:
No operators required on board during flights. Scientist required for calibrations between flights.

Data Collection:
self

Post-flight Data Validation, Processing, Hours per Flight Hour etc.


Physical Characteristics:
Dimensions: 24" of 19" rack space
Weight: 140 lbs
Power: < 4 amps 115 volt 60 Hz
Other: access to zenith and nadir optical collectors for calibrations

4. Instrument Performance

Linear Range:
6 orders of magnitude

Response Time:
5-10 sec/spectra

Detection Limits:
Actinic Flux ~0.5 uW/cm2/nm
Photolysis frequencies varies with molecule

Accuracy:
<10%

Precision:
3%

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

5. Alternative Techniques

6. Status/Plans

7. Comments