[A-AS04] Atmospheric Chemistry

[AAS04-P29] Scientific findings from observations of GOSAT/TANSO−FTS TIR band

*Naoko Saitoh¹, Shingo Kosaka¹, Masato Shiraki¹, Hinako Kobayashi¹ (1.Center for Environmental Remote Sensing)

Keywords:CO2, CH4, ozone, GOSAT/TANSO-FTS

Greenhouse Gases Observing Satellite (GOSAT) has continued its observations of greenhouse gases for more than 10 years since its launch on 23 January 2009. The thermal infrared (TIR) band of the Thermal and Near Infrared Sensor for Carbon Observation (TANSO)–Fourier Transform Spectrometer (FTS) on board GOSAT has observed concentrations of CO₂, CH₄ and other greenhouse gases in several atmospheric layers. In the latest TANSO–FTS TIR Level 2 retrieval algorithm, Version 1 (V1), ozone, water vapor, and temperature have been retrieved as by-products of the CO₂ and CH₄ products (Saitoh et al., 2016). We have already evaluated the data quality of the TANSO–FTS TIR V1 CO₂ and CH₄ products (Saitoh et al., 2016, 2017; Holl et al., 2016; Zou et al., 2016; Olsen et al., 2017). We applied the evaluated bias-correction values to the TANSO–FTS TIR V1 CO₂ data and compared variations in concentrations of the TIR CO₂ data with those of Measurement Of Pollution In The Troposphere (MOPITT) CO data [Deeter et al., 2014] in upper troposphere over the northern Africa. The comparison result showed that both TANSO−FTS TIR CO₂ and MOPITT CO concentrations became larger there almost at the same time in March through May, which suggests air mass with high CO and CO₂ emitted due to biomass burning was transported to upper atmosphere. As TANSO–FTS TIR V1 CH₄ profiles generally agreed with aircraft CH₄ profiles to within ~1% in the troposphere in low and middle latitudes, we analyzed seasonal variations in CH₄ concentrations in each altitude layer over India by using the TIR V1 CH₄ data. Our results were similar to the results reported in Chandra et al. (2017), but showed larger impact of CH₄ variations in lower troposphere on seasonal variations in XCH₄ concentrations. We have conducted validation analysis of TANSO–FTS TIR O₃ profiles simultaneously retrieved with the TIR V1 CO₂ product using Atmospheric Chemistry Experiment (ACE)–FTS and ozonesonde data. Although there was slightly high bias in the TANSO–FTS TIR O₃ data in the lower troposphere in summer, they showed better agreements with ACE–FTS and ozonesonde data than their a priori data taken from MacPeters et al. (2007). The TANSO–FTS TIR O₃ data in the lowest retrieval layer (surface−857 hPa) showed clear enhancements in O₃ concentrations over Mainland China compared to eastern Japan, which could demonstrate the detectability of tropospheric pollutants by the TANSO–FTS TIR band.