Updated Level-1 Processing After Two-years Operation of TANSO-FTS

To monitor the global column concentration of carbon dioxide (CO2) and methane (CH4) from space, the Greenhouse gases Observing SATellite (GOSAT) was launched on January 23, 2009, and has started the operational phase. Thermal and Near Infrared Sensor for Carbon Observation- Fourier Transform Spectrometer (TANSO-FTS) has been measuring CO2 and CH4 distributions globally every three days since April 2009, and data distribution to the public started on Feb. 16, 2010. During its first two years of operations, the radiometric, geometric and spectroscopic characterizations of TANSO have been continuously conducted to update the Level-1 processing algorithm. Here, we describe two corrections that have been recently developed, demonstrated and installed in the operational processing algorithm. One corrects the scan-speed instability caused by micro-vibration from the satellite, which has degraded the spectroscopic accuracy. This instability was compensated by re-sampling the interferogram. The other is non-linearity correction in the electronics. In this presentation, the details of the on-orbit characteristics and the current status of Level-1 procesing for TANSO will be presented.