Renovated GOSAT operation beyond the designed lifetime

Abstract

To observe the global column concentration of carbon dioxide (CO 2 ) and methane (CH 4 ) from space, the Greenhouse gases Observing SATellite (GOSAT) was launched on January 23, 2009, and has started the operational observation. Thermal and Near Infrared Sensor for Carbon Observation – Fourier Transform Spectrometer (TANSO-FTS) has been continuously measuring CO2 and CH4 distributions globally, and supporting the global carbon cycle elucidation. It is important to monitor the greenhouse gases in long-term period with same data quality. During 7.5 years operational periods, GOSAT passed the designed lifetime, which is 5 years, and some components report the change of characteristic in-orbit. The pointing mechanism, which has a capability of change a line of scene both of along track and cross track, is equipped on GOSAT. To keep the quality of spectra from TANSO-FTS and try to ambitious observation plan, the pointing mechanism is switched to the backup one in January 2015. In addition, the spectral resolution is degraded due to the bias of ZPD position science 2014. The compensation algorithm is developed and implemented on the operational system and completed the reprocessing for all passed observation data. The pointing mechanism, observation pattern, and processing algorithm were renovated, and GOSAT can provide the long-term and consistent quality spectra.