NCAR Airborne Instrumentation Inventory

1. INSTRUMENT IDENTIFICATION

Instrument Designation:
Peroxy Radical Mass Spectrometer

Instrument Acronym:
HO₂ CIMS

Instrument Measurements:

a) Trace Gas
HO₂ and HO₂+RO₂

b) Cloud Physics/Aerosol


c) Radiation/Optical/Electrical


d) Additional Capabilities


Resource Person/Developer:
Name: Chris Cantrell
Affiliation: ACD
Phone: (303) 497-1479
Email: cantrell@ucar.edu

Principle of Measurement:
Chemical conversion of HO₂ and RO₂ to OH then to H₂SO₄, followed by ion-molecule reaction to form HSO₄^(-) ion that is then detected by quadrupole mass spectrometer.

In situ/Remote/Flux Measurement:
In situ

2. INSTRUMENT APPLICATION

Scientific questions to be answered:
- partitioning of peroxy radicals between HO₂ and RO₂
- loss of HO₂ and RO₂ on tropospheric aerosols
- HO₂ and RO₂ control of NO_x partitioning and ozone production
- HO₂ and RO₂ control of H₂O₂ and ROOH formation

Field projects in which the instrument has been used:
OH instrument upon which this is based has been used in MLOPEX 2, TOHPE, ACE 1, PEM-TROPICS

Publications describing the instrument, applications and field project results:
Eisele, Tanner, Cantrell and Calvert, JGR, 101, 14665, 1996.
Eisele and Tanner, JGR, 96, 9295, 1991.
Cantrell, Shetter, Gilpin, Calvert, Eisele, JGR, 101, 14653, 1996.
Tanner and Eisele, JGR, 100, 2883, 1995.

3. Instrument Deployment

Altitude:
to 25000 ft

Aircraft Platform:
NCAR C-130
NASA P-3B

Inlet Configuration/Location:
Concentric tubes with front shroud - currently front left of aircraft body

Calibration/Cross Calibration:
Photolysis of H₂O vapor in inlet - intercompared with long path absorption at Fritz Peak/Caribou

Operator Requirements:
One

Data Collection:
self

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


Physical Characteristics:
Dimensions: About a 2-bay standard rack
Weight: About 400 lbs
Power: About 20 amps 60 Hz, 120V
Other:

4. Instrument Performance

Linear Range:
0.5 to 100 pptv

Response Time:
10 seconds

Detection Limits:
0.5 pptv

Accuracy:
± 20%

Precision:
± 10%

Limitations (such as altitude, airspeed, etc.)
Calibration difficult in dry upper troposphere - may have to design new calibration scheme in that region

5. Alternative Techniques

6.Status/Plans

7.Comments