Water vapor isotopologue retrievals from high-resolution GOSAT shortwave infrared spectra

• Published in: Atmospheric Measurement Techniques
• Main Authors: Frankenberg, C., Wunch, D., Toon, G., Risi, Camille, Scheepmaker, R., Lee, J. -E., Wennberg, P., Worden, J.
• Other Authors: Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, California Institute of Technology (CALTECH), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), SRON Netherlands Institute for Space Research (SRON)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology; Antarc*; Antarctica
• Online Access: https://hal.archives-ouvertes.fr/hal-01108535; https://hal.archives-ouvertes.fr/hal-01108535/document; https://hal.archives-ouvertes.fr/hal-01108535/file/amt-6-263-2013.pdf; https://doi.org/10.5194/amt-6-263-2013

International audience Remote sensing of the isotopic composition of water vapor can provide valuable information on the hydrological cycle. Here, we demonstrate the feasibility of retrievals of the relative abundance of HDO (the HDO/H2O ratio) from the Japanese GOSAT satellite. For this purpose, we use high spectral resolution nadir radiances around 6400 cm(-1) (1.56 mu m) to retrieve vertical column amounts of H2O and HDO. Retrievals of H2O correlate well with ECMWF (European Centre for Medium-Range Weather Forecasts) integrated profiles (r(2) = 0.96). Typical precision errors in the retrieved column-averaged deuterium depletion (delta D) are 20-40%. We compare delta D against a TCCON (Total Carbon Column Observing Network) ground-based station in Lamont, Oklahoma. Using retrievals in very dry areas over Antarctica, we detect a small systematic offset in retrieved H2O and HDO column amounts and take this into account for a bias correction of delta D. Monthly averages of delta D in the June 2009 to September 2011 time frame are well correlated with TCCON (r2 = 0.79) and exhibit a slope of 0.98 (1.23 if not bias corrected). We also compare seasonal averages on the global scale with results from the SCIAMACHY instrument in the 2003-2005 time frame. Despite the lack of temporal overlap, seasonal averages in general agree well, with spatial correlations (r2) ranging from 0.62 in September through November to 0.83 in June through August. However, we observe higher variability in GOSAT delta D, indicated by fitted slopes between 1.2 and 1.46. The discrepancies are likely related to differences in vertical sensitivities but warrant further validation of both GOSAT and SCIAMACHY and an extension of the validation dataset.