Laboratory spectral calibration of the TanSat atmospheric carbon dioxide grating spectrometer

TanSat is a key satellite mission in the Chinese Earth Observation program and is designed to measure the global atmospheric column-averaged dry-air CO2 mole fraction by measuring the visible and near-infrared solar-reflected spectra. The first Chinese super-high-resolution grating spectrometer for measuring atmospheric CO2 is aboard TanSat. This spectrometer is a suite incorporating three grating spectrometers that make coincident measurements of reflected sunlight in the near-infrared CO2 band near 1.61 and 2.06&thinsp;µm and in the molecular oxygen (O2) A-band at 0.76&thinsp;µm. The spectral resolving power (λ∕Δλ) values are  ∼ 19&thinsp;000,  ∼ 12&thinsp;800, and  ∼ 12&thinsp;250 in the O2 A-band, and the weak and strong absorption bands of CO2, respectively. This paper describes the prelaunch spectral calibration of the atmospheric carbon dioxide grating spectrometer aboard TanSat. Several critical aspects of the spectrometer, including the spectral resolution, spectral dispersion, and the instrument line shape function of each channel, which are directly related to producing the Level 1 products are evaluated in this paper. The instrument line shape function of the spectrometer is notably symmetrical and perfectly consistent across all channels in the three bands. The symmetry is better then 99.99&thinsp;%, and the consistency in the worst case is better then 99.97&thinsp;%, 99.98&thinsp;%, and 99.98&thinsp;% in the O2 A, WCO2, and SCO2 bands, respectively. The resulting variations in the spectral calibrations and the radiometric response errors are negligible. The spectral resolution characterizations meet the mission requirements. The spectral dispersions have excellent consistency in the spatial dimension of each band, and there is good linearity in the spectral dimension of each band. The RMS errors of the fitting residuals are 0.9, 1, and 0.7&thinsp;pm in the O2 A-band, the WCO2 band, and the SCO2 band, respectively. Taken together, these results suggest that the spectral characterizations of the spectrometer aboard TanSat meet the mission requirements.</p

13 th International Workshop on Greenhouse Gas Measurements from Space : Book of Abstracts

The 13th International Workshop on Greenhouse Gas Measurements from Space (IWGGMS) will be held on 6-8 June, 2017, at the University of Helsinki in Helsinki, Finland. The workshop is organised by the Finnish Meteorological Institute with support from the University of Helsinki. The workshop gathers together more than 160 scientists from the EU, USA, Japan, China, Australia, Canada, and Russia. This report is the official abstract book of the workshop. Background. Success in space-based global measurement of greenhouse gases, such as carbon dioxide and methane, is critical for advancing the understanding of carbon cycle. The recent developments in observations and in interpreting the data are very promising. Space-based greenhouse gas measurement, however, poses a wide array of challenges, many of which are complex and thus demand close international cooperation. The goal of the workshop is to review the state of the art in remote sensing of CO 2 , CH 4 , and other greenhouse gases from space including the current satellite missions, missions to be launched in the near future, emission hot spots on regional and global scales, process studies and interactions of carbon cycle and climate, pre-flight and on-orbit instrument calibration techniques, retrieval algorithms and uncertainty quantification, validation methods and instrumentation, related ground-based, shipboard, and airborne measurements, and flux inversion from space based measurements. The workshop is part of the programme for the centenary of Finland's independence in 2017. The workshop is also one of the activities arranged by the Finnish Meteorological Institute to support Finland's chairmanship of the Arctic Council, 2017 - 2019. The workshop is sponsored by the Finnish Meteorological Institute, the University of Helsinki, the European Space Agency, the City of Helsinki, the Federation of Finnish Learned Societies, and ABB Inc