NCAR Airborne Instrumentation Inventory

1. INSTRUMENT IDENTIFICATION

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

Instrument Acronym:
SI/CIMS-2

Instrument Measurements:

a) Trace Gas
OH, H₂SO₄, MSA, DMSO, DMSO₂

b) Cloud Physics/Aerosol


c) Radiation/Optical/Electrical


d) Additional Capabilities


Resource Person/Developer:
Name: Eisele/Tanner/Mauldin
Affiliation: NCAR/ACD
Phone: (303) 497-1483
Email: eisele@acd.ucar.edu

Principle of Measurement:
Titration of OH in H₂SO₄ and measurement of H₂SO₄ and MSA via proton exchange with NO₃^-. DMSO and DMSO₂ are reacted with NH₄⁺ 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; DMSO and DMSO₂ to investigate DMS oxidation process and its relation to particle production and growth.

Field projects in which the instrument has been used:
Ground-based MLOPEX-II, OH Photochemistry experiment; aircraft-based ACE-1 and PEM Tropics.

Publications describing the instrument, applications and field project results:

"The H₂SO₄ Vapor Pressure Above Sulfuric Acid and Ammonium Sulfate Solutions", J.J. Marti, A. Jefferson, X. Ping Cai, C. Richert, P.H. McMurry, and F. Eisele, J. of Geophysical Res., accepted.

"Peroxy Radicals from Photostationary State Deviations and Steady State Calculations During the Tropospheric OH Photochemistry Experiment at Idaho Hill, Colorado 1993", C.A. Cantrell, R.E. Shetter, J.G. Calvert, F.L. Eisele, E.J. Williams, K. Baumann, W.H. Brune, P.S. Stevens, and J.H. Mather, J. of Geophysical Res., accepted.

"Photochemical Modeling of Hydroxyl and its Relationship to Other Species During the Tropospheric OH Experiment", S.A. McKeen, G. Mount, F. Eisele, E. Williams, J. Harder, P. Goldan, W. Kuster, S.C. Liu, K. Baumann, D. Tanner, A. Fried, S. Sewell, C. Cantrell, and R. Shetter, J. of Geophysical Res., accepted.

"Understanding the Production and Interconversion of the Hydroxyl Radical During the Tropospheric OH Photochemistry Experiment, " F.L. Eisele, G.H. Mount, D. Tanner, A. Jefferson, R. Shetter, J.W. Harder, and E.J. Williams, J. of Geophysical Res., accepted.

"An Intercomparison of Spectroscopic Laser Long Path and Ion Assisted in situ Measurements of Hydroxyl Concentrations During the Tropospheric OH Photochemistry Experiment, Fall 1993," J. of Geophysical Res., accepted.

"Selected Ion Chemical Ionization Mass Spectrometric Measurements of OH," D. Tanner, A. Jefferson, and F. Eisele, J. of Geophysical Res., 101, 14,665, 1996.

"Measurements and Steady State Calculations of OH Concentrations at MLO," F.L. Eisele, D.J. Tanner, C.A. Cantrell, and J.G. Calvert, J. of Geophysical Res.,101, 14,653, 1996.

"Peroxy Radical Concentrations Measured and Calculated from Trace Gas Measurements in MLOPEX-II," C.A. Cantrell, R.A. Shetter, T.M. Gilpin, J.G. Calvert, F.L. Eisele, and D.J. Tanner, J. of Geophysical Res., 151, 53.1006.

"Measured Atmospheric New Particle Formation Rates: Implications for Nucleation Theory," R.J. Weber, J.J. Marti, P.H. Mc Murry, F.L. Eisele, D.J. Tan