NCAR Airborne Instrumentation Inventory

1. INSTRUMENT IDENTIFICATION

Instrument Designation:
4-channel selected ion chemical ionization mass spectrometer

Instrument Acronym:
SI/CIMS-4

Instrument Measurements:

a) Trace Gas
OH, H₂SO₄, MSA, HNO₃ and others depending on mission

b) Cloud Physics/Aerosol


c) Radiation/Optical/Electrical


d) Additional Capabilities


Resource Person/Developer:
Name: Eisele/Tanner/Mauldin
Affiliation: ACD
Phone:
Email:eisele@acd.ucar.edu

Principle of Measurement:
Titration of OH into H₂SO₄ and measurement of H₂SO₄ and MSA via proton exchange with NO₃^-. HNO₃ reactant ions. In all cases concentrations are determined by product/reactant ion ratios. Ion ratios are measured with quadrupole mass spectrometers.

In situ/Remote/Flux Measurement:

2. INSTRUMENT APPLICATION

Scientific questions to be answered:
OH measurements used to understand fast photooxidation chemistry; H₂SO₄ used to investigate particle nucleation; H₂SO₄ and MSA used to understand particle growth; HNO₃ is an important product of OH + NO₂ reaction.

Field projects in which the instrument has been used:
n/a

Publications describing the instrument, applications and field project results:
n/a

3. Instrument Deployment

Altitude:
30,000 - 65,000 feet

Aircraft Platform:
WB-57 or similar

Inlet Configuration/Location:
Shroud with cylindrical diffusers. Location bottom of WB-57.

Calibration/Cross Calibration:
Onboard ambient air calibration/2 ground based intercomparisons.

Operator Requirements:
zero

Data Collection:
self

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

Physical Characteristics:
Dimensions: 3 (4 foot pallet)
Weight: 800 lbs
Power:
Other:

4. Instrument Performance

Linear Range:
linear over ambient level range

Response Time:
30 seconds OH, H₂SO₄, MSA; 2 seconds HNO₃

Detection Limits:
OH and MSA 2(10x5 cm^-3, H₂SO₄ 1x10⁵, HNO₃ 10 pptv

Accuracy:
to be tested

Precision:


Limitations (such as altitude, airspeed, etc.)

5. Alternative Techniques

6.Status/Plans

7.Comments