Aircraft Measurements for Calibration of the NIES TCCON FTSs and Comparison of the GOSAT Data Observed over Tsukuba and Rikubetsu in Japan

Thursday, 18 December 2014
Makoto Inoue, Isamu Morino, Osamu Uchino, Kumi Nakamae, Toshinobu Machida, Keiichi Katsumata and Tatsuya Yokota, National Institute for Environmental Studies, Tsukuba city, Ibaraki, Japan
The Total Carbon Column Observing Network (TCCON) is a global network of ground-based high-resolution Fourier Transform Spectrometers (FTSs) that record direct solar spectra in the near-infrared. From these spectra, accurate and precise column-averaged dry-air mole fractions of atmospheric constituents including CO2, CH4, N2O, HF, CO, H2O, and HDO are retrieved. The National Institute for Environmental Studies (NIES) operates two TCCON FTSs at Tsukuba (36.05°N, 140.12°E) and Rikubetsu (43.46°N, 143.77°E) in Japan.

We made the aircraft measurements over Tsukuba and Rikubetsu in January 2014 to calibrate the TCCON FTSs and to compare with XCO2 and XCH4 retrieved from the Short-Wavelength InfraRed (SWIR) spectra of Thermal And Near-infrared Sensor for carbon Observation - Fourier Transform Spectrometer (TANSO-FTS) onboard the Greenhouse gases Observing SATellite (GOSAT). In situ NDIR (CO2) and CRDS (CO2 and CH4) measurements and flask sampling (CO2, CH4, CO, N2O, and so on) were conducted onboard aircraft (Beechcraft King Air 200T) operated by Diamond Air Service Inc. from about 400 m to 9500 m. In addition, cloud observation by whole-sky camera and meteorological observation with radiosondes were performed from the ground in time with each flight. CO2 concentrations obtained from NDIR, CRDS, and flask sampling at respective heights generally agreed within 1 ppm. We calculated XCO2, XCH4, XCO, and XN2O from aircraft vertical profiles and XH2O from radiosonde measurements. Comparisons between them and TCCON data showed acceptable results on calibration for CO2, CH4, CO, N2O, and H2O of two TCCON FTSs. We also present comparisons between aircraft data and the GOSAT data.