HR: 0800h
AN: A41A-0027    [Abstracts]
TI: Validation of OMI Measured Radiances Over Ice
AU: * Jaross, G
EM: jaross@qhearts.gsfc.nasa.gov
AF: Science Systems and Applications, Inc., 10210 Greenbelt Rd., Ste. 400, Lanham, MD 20706 United States
AU: Cebula, R P
A41A-0027 AF: Science Systems and Applications, Inc., 10210 Greenbelt Rd., Ste. 400, Lanham, MD 20706 United States
AU: Warner, J
A41A-0027 AF: Science Systems and Applications, Inc., 10210 Greenbelt Rd., Ste. 400, Lanham, MD 20706 United States
AB: The Ozone Monitoring Instrument (OMI) was launched aboard the EOS Aura satellite on 15 July, 2004 and has since performed quite well. Calibrated radiances in the form of Level 1 data products are produced regularly every orbit with minimal data loss. A total of 12 atmospheric constituent data products are currently planned for the OMI science data processing. All rely, to varying degrees, on the sun-normalized radiances of the OMI sensor. Retrievals of atmospheric trace constituents, such as NO{}_2, BrO, OCLO, and HCHO, rely upon spectroscopy and tend to be insensitive to errors in the absolute radiance levels. But column O{}_3 amount, aerosol properties, cloud heights, and UV surface radiation have significant sensitivities to changes in the sun-normalized radiances. In this presentation we discuss our evaluation of the OMI sun-normalized radiances between 330 nm and 500 nm. This covers most of the OMI spectral range where ozone absorption is small. Our technique involves a comparison of normalized radiances measured by OMI over the Antarctic continent with top-of-the-atmosphere (TOA) values computed with a radiative transfer model. In our model we assume a Rayleigh-scattering, aerosol-free, cloud-free atmosphere, and a mean surface reflectance derived from measurements on the ground. TOA radiances are sensitive to the bi-directional distribution of surface reflectance, especially at high solar zenith angles. We have developed a surface reflectance model to help correct these effects, but it still remains the largest source of uncertainty. We estimate the residual uncertainty at all wavelengths to be 2%.
DE: 0360 Radiation: transmission and scattering
DE: 0394 Instruments and techniques
DE: 0726 Ice sheets
DE: 3394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005