Validation and Extension of SCIAMACHY Water Vapor Isotopologues Measurements
Scheepmaker, Remco¹; Frankenberg, Christian²; Deutscher, Nicholas³; Schneider, Matthias⁴; Landgraf, Jochen⁵; Aben, Ilse^5
1SRON Netherlands Institute for Space Research, NETHERLANDS; ²JPL, UNITED STATES; ³IUP, GERMANY; ⁴KIT IMK-ASF, GERMANY; ⁵SRON, NETHERLANDS

The relative abundance of the heavy water isotopologue HDO provides a deeper insight in the atmospheric hydrological cycle, because evaporation and condensation processes deplete heavy water in the gas phase. A better understanding of the hydrological cycle is crucial for climate predictions, climate reconstructions and water resources management. We study the near-surface distribution of water vapor isotopologues using satellite retrievals of global HDO/H2O abundances. For our satellite retrievals we use the 2.3 micron (SWIR) channel of the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) instrument on-board ENVISAT. Here we show the latest results of our ongoing effort to improve the dataset, extend it to the end of the ENVISAT mission (April 2012), and validate it against ground-based total column measurements of atmospheric HDO/H2O. For the validation we compare the data against SWIR measurements from the Total Carbon Column Observing Network (TCCON) and infrared measurements from the Network for the Detection of Atmospheric Composition Change (NDACC). Furthermore, we provide an outlook for the new Tropospheric Monitoring Instrument (TROPOMI), scheduled for launch in mid 2015 on-board ESA's Sentinel-5 Precursor satellite. Using our SCIAMACHY heritage, we aim to improve the near-surface water vapor isotopologue retrievals with TROPOMI's smaller ground pixels, shorter revisit time (due to a larger swath) and increased sensitivity.