Quality Flag of GOSAT/FTS Products Taking into Account Estimation Reliability

Kohei Arai,Hirofumi Ohyama,Kei Shiomi,Shuji Kawakami,Hiroshi Okumura,Takashi Higuchi

doi:10.14569/ijacsa.2018.090909

Abstract

Quality and cloud flags of GOSAT/FTS: Fourier Transform Spectrometer onboard Greenhouse gasses Observation Satellite products taking into account cirrus clouds and thick aerosols are considered and proposed. Influence due to cirrus and thick aerosol on estimation of column CO2 and CH4 with GOSAT/FTS data is clarified. Relatively large estimation errors are observed in column CO2 and CH4 retrievals with FTS data in some atmospheric conditions. In order to find such cases, retrieval results and quality/cloud flags in the GOSAT/FTS data products are checked. Through the investigation, it is found that relatively large error is caused by convergence problem due to cirrus clouds and thick aerosols. In the proposed paper, some of the cases of which relatively large estimation error is occurred at the Saga TCCON (The Total Carbon Column Observing Network) site are investigated. Also, a comparative study is conducted between standard products provided by NASA/JPL and the Levenberg-Marquardt based least square method of column CO2 and CH4 retrieval. It is suggested that some improvements of estimation accuracy of column CO2 and CH4 retrieval with GOSAT/FTS data can be expected.

Highlights

GOSAT: Greenhouse gases Observing Satellite is a greenhouse gas observation technology satellite (“IBUKI” in Japanese) 1 jointly developed by the Ministry of the Environment, the National Institute for Environmental Studies (NIES), and the Japan Aerospace Exploration Agency (JAXA)
Quality and cloud flags of GOSAT/TANSO-FTS: Fourier Transform Spectrometer onboard Greenhouse gasses Observation Satellite products taking into account cirrus clouds and thick aerosols are considered and proposed
Large estimation errors are observed in column CO2 and CH4 retrievals with FTS data in some atmospheric conditions

Summary

INTRODUCTION

GOSAT carries TANSO-CAI (CAI: Cloud and Aerosol Imager) is an image sensor used for determination of the presence or absence of clouds and measurement of aerosol (atmospheric particulate matter), which is an error factor when measuring carbon dioxide at TANSO-FTS It is a secondary sensor of IBUKI. Impact of aerosol and cirrus clouds on the GOSAT observed CO2 and CH4 inferred from ground based lidar, skyradiometer 10 and FTS data at prioritized observation sites,(2013) is clarified [11]. Impact of aerosols and cirrus on the GOSAT onboard CO2 and CH4 inferred from ground based Lidar, skyradiometer and FTS data at prioritized observation sites is discussed [13]. Influence due to cirrus and thick aerosol on estimation of column CO2 and CH4 with GOSAT/FTS data is discussed [17]. Conclusion is described together with some discussions and with future research works

Present Status of GOSAT Project

Possible Causes of Relatively Large XCO2 Estimation Error

CONCLUSION