[ACG49-P01] How the GOSAT program has used airplane observations for its demonstration, calibration, and validation
Keywords:GOSAT, TANSO-FTS, ARIES, AJAX, S-HIS
(1) Demonstration of GHG column density retrieval from solar scattered light
At the beginning of the GOSAT program, we installed a breadboard model to a high altitude airplane to acquire spectra and to detect and correct light path modifications by aerosols and clouds. We acquired high resolution spectra of O2A, CO2, and CH4 at SWIR, but validation without a simultaneous aerosol Lidar measurement was not possible.
(2) TIR radiometric, spectroscopic and polarimetric calibrations
GOSAT observes wide spectral range radiation between 650 and 1800 cm-1 from both the surface and the atmosphere. Double difference comparison using spectra acquired by GOSAT, airplanes, and forward calculation can remove model-dependent errors. S-HIS-FTS by the University of Wisconsin onboard ER-2 at 25 km flown over the hot desert of Railroad Valley (RRV) and S-HIS and the Met Office ARIES FTS operated onboard FAAM flown over cold Greenland provided calibration data for detector non-linearity correction. Additionally, high spectral resolution data from air-borne FTSs validated spectroscopic and polarimetric calibrations.
(3) Validation of GHG vertical profile
A multiplex advantage of GOSAT-FTS can cover both solar scattered light at the SWIR band for column density and thermal radiation from the atmosphere at the TIR band for profile retrieval. NASA Ames’s Alpha Jet Atmospheric eXperiment (AJAX) uses a Picarro spectrometer for the in-situ vertical spiral profiling of CO2 and CH4 from the surface to the upper troposphere and coincident flight data for GOSAT over RRV.
In addition to the above applications, airplanes can provide plume emissions with a higher spatial scale to validate amount from point sources.