Optimal Estimation Retrievals of CO2 from AIRS spectra

Since September 2002, the Atmospheric Infrared Sounder (AIRS) on the EOS-Aqua platform has globally observed atmospheric profile information from nadir viewing of infrared emittance. Selecting cloud-free spectra over ocean, we apply an optimal estimation algorithm, similar to that used for the Tropospheric Emission Spectrometer (TES), to simultaneously retrieve profiles of CO2, water vapor, ozone, temperature and ocean skin temperature. Preliminary results and validation over the Western Pacific are presented, showing good correlation with seasonal variation and long-term increase of CO2 as determined by in-situ aircraft measurements.