NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Air Mass Factor Formulation for Spectroscopic Measurements from Satellites: Application to Formaldehyde Retrievals from the Global Ozone Monitoring ExperimentWe present a new formulation for the air mass factor (AMF) to convert slant column measurements of optically thin atmospheric species from space into total vertical columns. Because of atmospheric scattering, the AMF depends on the vertical distribution of the species. We formulate the AMF as the integral of the relative vertical distribution (shape factor) of the species over the depth of the atmosphere, weighted by altitude-dependent coefficients (scattering weights) computed independently from a radiative transfer model. The scattering weights are readily tabulated, and one can then obtain the AMF for any observation scene by using shape factors from a three dimensional (3-D) atmospheric chemistry model for the period of observation. This approach subsequently allows objective evaluation of the 3-D model with the observed vertical columns, since the shape factor and the vertical column in the model represent two independent pieces of information. We demonstrate the AMF method by using slant column measurements of formaldehyde at 346 nm from the Global Ozone Monitoring Experiment satellite instrument over North America during July 1996. Shape factors are cumputed with the Global Earth Observing System CHEMistry (GEOS-CHEM) global 3-D model and are checked for consistency with the few available aircraft measurements. Scattering weights increase by an order of magnitude from the surface to the upper troposphere. The AMFs are typically 20-40% less over continents than over the oceans and are approximately half the values calculated in the absence of scattering. Model-induced errors in the AMF are estimated to be approximately 10%. The GEOS-CHEM model captures 50% and 60% of the variances in the observed slant and vertical columns, respectively. Comparison of the simulated and observed vertical columns allows assessment of model bias.
Document ID
20040111411
Acquisition Source
Langley Research Center
Document Type
Reprint (Version printed in journal)
Authors
Palmer, Paul I.
(Harvard Univ. Cambridge, MA, United States)
Jacob, Daniel J.
(Harvard Univ. Cambridge, MA, United States)
Chance, Kelly
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Martin, Randall V.
(Harvard Univ. Cambridge, MA, United States)
Spurr, Robert J. D.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Kurosu, Thomas P.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Bey, Isabelle
(Harvard Univ. Cambridge, MA, United States)
Yantosca, Robert
(Harvard Univ. Cambridge, MA, United States)
Fiore, Arlene
(Harvard Univ. Cambridge, MA, United States)
Li, Qinbin
(Harvard Univ. Cambridge, MA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2004
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 106
Issue: D13
ISSN: 0148-0227
Subject Category
Geophysics
Report/Patent Number
Paper-2000JD900772.
Funding Number(s)
CONTRACT_GRANT: NAG1-2307
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available