The primary instrument on the Greenhouse gases Observing SATellite (GOSAT) is the Thermal And Near infrared Sensor for carbon Observations (TANSO) Fourier Transform Spectrometer (FTS). GOSAT is a joint venture by Japan's Ministry of the Environment (MOE), National Institute for Environmental Studies (NIES), and the Japan Aerospace Exploration Agency (JAXA). TANSO-FTS uses three short-wave infrared (SWIR) bands to retrieve total columns of CO2 and CH4 along its optical line-of-sight and one thermal infrared TIR channel to retrieve vertical profiles of CO2 and CH4 volume mixing ratios (VMRs) in the troposphere. We examine version 1 of the TANSO-FTS TIR CH4 product by comparing co-located CH4 VMR vertical profiles from two other remote sensing FTS systems: the CSA's Atmospheric Chemistry Experiment- (ACE-) FTS on SCISAT (version 3.5) and the ESA's Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat (ESA ML2PP version 6 and IMK reduced-resolution version V6R). This work follows an initial inter-comparison study over the Arctic which incorporated a ground-based FTS at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Canada (Holl et al. 2015), and focuses on tropospheric measurements made at middle and tropical latitudes between 2009 to 2013 (mid 2012 for MIPAS). The coincidence criteria imposed for CH4 observations is that ACE-FTS and MIPAS measurements must be made within 12 hours and 500 km of a TANSO-FTS TIR measurement, and the ACE-FTS, IMK MIPAS and ESA MIPAS measurements must extend down to below 10, 12 and 12 km, respectively. For comparison, all three instruments are interpolated onto a fixed pressure grid, the ACE-FTS and MIPAS vertical profiles are smoothed using the TANSO-FTS averaging kernels, and measurements made on the pressure grid without overlapping coincident measurements are discarded. We present zonally-averaged mean CH4 differences between each instrument and TANSO-FTS with and without smoothing, and examine their information content, sensitive altitude range, correlation, a priori dependence, and the variability within each data set. Initial results show that the TANSO-FTS vertical profiles agree with the ACE-FTS and both MIPAS vertical profiles within 4% below 20 km when smoothing is applied to the instruments with finer vertical resolution, but that the relative differences can increase to on the order of 25% when no smoothing is applied.
Validation of the GOSAT TANSO-FTS TIR CH4 vertical profile data product using CH4 vertical profiles from MIPAS (ESA and IMK) and ACE-FTS
Piera Raspollini;
2016
Abstract
The primary instrument on the Greenhouse gases Observing SATellite (GOSAT) is the Thermal And Near infrared Sensor for carbon Observations (TANSO) Fourier Transform Spectrometer (FTS). GOSAT is a joint venture by Japan's Ministry of the Environment (MOE), National Institute for Environmental Studies (NIES), and the Japan Aerospace Exploration Agency (JAXA). TANSO-FTS uses three short-wave infrared (SWIR) bands to retrieve total columns of CO2 and CH4 along its optical line-of-sight and one thermal infrared TIR channel to retrieve vertical profiles of CO2 and CH4 volume mixing ratios (VMRs) in the troposphere. We examine version 1 of the TANSO-FTS TIR CH4 product by comparing co-located CH4 VMR vertical profiles from two other remote sensing FTS systems: the CSA's Atmospheric Chemistry Experiment- (ACE-) FTS on SCISAT (version 3.5) and the ESA's Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat (ESA ML2PP version 6 and IMK reduced-resolution version V6R). This work follows an initial inter-comparison study over the Arctic which incorporated a ground-based FTS at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Canada (Holl et al. 2015), and focuses on tropospheric measurements made at middle and tropical latitudes between 2009 to 2013 (mid 2012 for MIPAS). The coincidence criteria imposed for CH4 observations is that ACE-FTS and MIPAS measurements must be made within 12 hours and 500 km of a TANSO-FTS TIR measurement, and the ACE-FTS, IMK MIPAS and ESA MIPAS measurements must extend down to below 10, 12 and 12 km, respectively. For comparison, all three instruments are interpolated onto a fixed pressure grid, the ACE-FTS and MIPAS vertical profiles are smoothed using the TANSO-FTS averaging kernels, and measurements made on the pressure grid without overlapping coincident measurements are discarded. We present zonally-averaged mean CH4 differences between each instrument and TANSO-FTS with and without smoothing, and examine their information content, sensitive altitude range, correlation, a priori dependence, and the variability within each data set. Initial results show that the TANSO-FTS vertical profiles agree with the ACE-FTS and both MIPAS vertical profiles within 4% below 20 km when smoothing is applied to the instruments with finer vertical resolution, but that the relative differences can increase to on the order of 25% when no smoothing is applied.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
