HR: 08:30h
AN: A31A-03    [PDF]
TI: Retrieval of Oxygen A-Band Spectra from Airborne Measurements
AU: * Natraj, V
EM: vijay@gps.caltech.edu
AF: California Institute of Technology, Division of Geological and Planetary Sciences, MC 170-25, 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Kuang, Z
EM: kzm@atmos.washington.edu
AF: University of Washington, Department of Atmospheric Sciences, 408 ATG Bldg., Box 351640, Seattle, WA 98195 United States
AU: Yang, Z
EM: yangzh@gps.caltech.edu
AF: California Institute of Technology, Division of Geological and Planetary Sciences, MC 170-25, 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Toon, G C
EM: toon@caesar.jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: O'Brien, D
EM: denis.obrien@csiro.au
AF: CSIRO, Division of Atmospheric Research, Aspendale, VIC 3195 Australia
AU: Crisp, D
EM: David.Crisp@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Yung, Y L
EM: yly@gps.caltech.edu
AF: California Institute of Technology, Division of Geological and Planetary Sciences, MC 170-25, 1200 E. California Blvd., Pasadena, CA 91125 United States
AB: A strategy to measure the column averaged CO$_{2}$ dry air volume mixing ratio, X$_{CO_{2}}$, from space was introduced by Kuang {\it et al} (2002), which employs high resolution spectra of reflected sunlight taken simultaneously in near-infrared CO$_{2}$ (1.58 $\mu$m and 2.06 $\mu$m) and O$_{2}$ (0.76 $\mu$m) bands. The retrieval algorithm involves a line-by-line, multi-stream, multiple scattering model for producing synthetic radiance spectra in scattering and absorbing atmospheres; a wavelength-dependent instrument line shape function; and an inverse method based on optimal estimation theory (Rodgers, 2000). To test the retrieval scheme, we used high-precision, high-resolution O$_{2}$ A-band spectra (759-771 nm) of sunlight reflected from the sea surface (O'Brien {\it et al}., 1996). These spectra were obtained with a grating spectrograph directed toward sunglint on the sea surface from a research airplane. Using the retrieval algorithm, we were able to retrieve a sample spectrum to within an rms error of 1.5%. This spectrum required wavelength scaling to match the calculated spectrum. The continuum level, tilt and a zero level offset were fitted. The objective is to retrieve surface pressures with precisions between 0.1-0.3% from this data set. This is the next logical step in demonstrating the feasibility of retrieving X$_{CO_{2}}$ from space with precision near 0.3%.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0360 Transmission and scattering of radiation
DE: 0394 Instruments and techniques
DE: 0399 General or miscellaneous
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting