Water vapor isotopologue retrievals from high-resolution GOSAT shortwave infrared spectra
Open Access
- 7 February 2013
- journal article
- Published by Copernicus GmbH in Atmospheric Chemistry and Physics
- Vol. 6 (2), 263-274
- https://doi.org/10.5194/amt-6-263-2013
Abstract
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 μm) 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 (r2 = 0.96). Typical precision errors in the retrieved column-averaged deuterium depletion (δD) are 20–40‰. We compare δD 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 δD. Monthly averages of δD 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 δD, 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.Keywords
This publication has 48 references indexed in Scilit:
- Atmospheric validation of high accuracy CO2 absorption coefficients for the OCO-2 missionJournal of Quantitative Spectroscopy and Radiative Transfer, 2012
- Improved water vapour spectroscopy in the 4174–4300 cm−1 region and its impact on SCIAMACHY HDO/H2O measurementsPublished by Copernicus GmbH ,2012
- The ACOS CO2 retrieval algorithm – Part II: Global XCO2 data characterizationAtmospheric Chemistry and Physics, 2012
- A method for evaluating bias in global measurements of CO2 total columns from spaceAtmospheric Chemistry and Physics, 2011
- New global observations of the terrestrial carbon cycle from GOSAT: Patterns of plant fluorescence with gross primary productivityGeophysical Research Letters, 2011
- Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground‐based TCCON data and model calculationsGeophysical Research Letters, 2011
- Tropical methane emissions: A revised view from SCIAMACHY onboard ENVISATGeophysical Research Letters, 2008
- Marine boundary layer clouds at the heart of tropical cloud feedback uncertainties in climate modelsGeophysical Research Letters, 2005
- Measurements of positions, strengths and self-broadened widths of H2O from 2900 to 8000 cm−1: line strength analysis of the 2nd triad bandsJournal of Quantitative Spectroscopy and Radiative Transfer, 2005
- Measured HDO/H2O ratios across the tropical tropopauseGeophysical Research Letters, 2003