Analyzing six-year-long GOSAT Observational Data

Abstract:

The Greenhouse gases Observing SATellite (GOSAT) has been operating for more than six-and-a-half years since January 2009. In 2014, GOSAT went through some technical difficulties in the functioning of its solar paddle and sensor pointing mechanism. These problems were overcome later, and the GOSAT observation is still continued without major flaws. GOSAT TANSO-FTS SWIR Level 2 data products, the column-averaged concentrations of carbon dioxide (XCO₂) and methane (XCH₄) calculated over the past measurement period, have been validated and disseminated to registered researchers and the general public by the NIES GOSAT Project. Also, monthly regional fluxes of CO₂ and CH₄ (Level 4A data products) over a few year period have been estimated from the FTS SWIR Level 2 data and ground-based GHG monitoring data.

Although the above-mentioned technical problems caused a data discontinuity, we accumulated FTS SWIR Level 2 data for more than six years. It is expected that more data will be collected for a few more years while the satellite remains operational. Anomalies in the time series of regional-mean column-averaged concentrations and fluxes are being investigated. In this presentation, we will show the results of the investigation, particularly the ones for some tropical and sub-tropical regions where only few retrievals were obtained due to the influence of frequent cloudiness. Also, we will touch changes in the number of retrievals found over these regions after modifying the satellite’s observational pattern.

The GOSAT Research Announcement (RA) activities by selected researchers are still continued. In analyzing long-term GOSAT data, events of concentration anomalies (e.g. in 2010 in Europe and in the US, and similar ones in 2013) were found by some of the RA studies. We will summarize the characteristics of GOSAT data products generated over the past several years, and some of the important research outcomes brought by the GOSAT RA researchers.