Vicarious calibration and validation campaign of the GOSAT sensors at Railroad Valley
Abstract
We report analytical results on the latest vicarious radiometric calibration and validation campaign for the Greenhouse gases Observing SATellite (GOSAT), which was launched on January 23, 2009. There are two independent sensors; the Thermal and Near Infrared Sensor for carbon Observations Fourier Transform Spectrometer (TANSO-FTS) and the Cloud and Aerosol Imager (TANSO-CAI). The campaign was performed in June every year since 2009 at the Railroad Valley desert playa, Nevada test site. The main objective is to calibrate the radiometric response on orbit by comparing the model calculated spectral radiance at the top of the atmosphere from ultraviolet UV to thermal infrared (TIR). We measured all the input parameters for the radiative transfer model; surface albedo, Bi-directional Reflectance Distribution Functions (BRDFs), surface temperature, surface emissivity, aerosol optical thickness, and vertical profiles of temperature and humidity. These results are corroborated by independent over-flight measurements from the Airborne Visible/InfraRed Imaging Spectrometer (AVIRIS) for visible and short wave infrared (SWIR) spectral radiance and Scanning High-resolution Interferometer Sounder (S-HIS) for TIR spectral radiance onboard the ER-2 airplane. From the annual validation campaign results, we have corrected degradation of TNASO-FTS oxygen (O2) A band. The accurate absolute radiometric correction has improved the estimation of the aerosol scattering, which is the major green gas observation error. Our campaign results also confirm the accurate radiometric calibration of both solar light reflection and thermal radiation. The other objective is the validation of carbon dioxide (CO2) and methane (CH4). We measure surface CO2 and CH4 with a cavity ring down spectrometer. At the same time, we measured horizontal distribution by the Sensor Integrated Environmental Remote Research Aircraft (SIERRA) and vertical profile by the alpha jet. The comparison between the in-situ data and GOSAT remotely observed data is presented and we will demonstrate how accurately we can measure CO2 and CH4 from space. The retrieval error such as aerosol optical depth, surface pressure, and surface albedo is also discussed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.A42D..07K
- Keywords:
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- 0322 ATMOSPHERIC COMPOSITION AND STRUCTURE / Constituent sources and sinks;
- 0360 ATMOSPHERIC COMPOSITION AND STRUCTURE / Radiation: transmission and scattering;
- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry;
- 0394 ATMOSPHERIC COMPOSITION AND STRUCTURE / Instruments and techniques