RT Journal Article SR Electronic T1 Dynamic Processes Governing Lower-Tropospheric HDO/H2O Ratios as Observed from Space and Ground JF Science JO Science FD American Association for the Advancement of Science SP 1374 OP 1377 DO 10.1126/science.1173791 VO 325 IS 5946 A1 Frankenberg, Christian A1 Yoshimura, Kei A1 Warneke, Thorsten A1 Aben, Ilse A1 Butz, André A1 Deutscher, Nicholas A1 Griffith, David A1 Hase, Frank A1 Notholt, Justus A1 Schneider, Matthias A1 Schrijver, Hans A1 Röckmann, Thomas YR 2009 UL http://science.sciencemag.org/content/325/5946/1374.abstract AB The hydrological cycle and its response to environmental variability such as temperature changes is of prime importance for climate reconstruction and prediction. We retrieved deuterated water/water (HDO/H2O) abundances using spaceborne absorption spectroscopy, providing an almost global perspective on the near-surface distribution of water vapor isotopologs. We observed an unexpectedly high HDO/H2O seasonality in the inner Sahel region, pointing to a strong isotopic depletion in the subsiding branch of the Hadley circulation and its misrepresentation in general circulation models. An extension of the analysis at high latitudes using ground-based observations of δD¯ and a model study shows that dynamic processes can entirely compensate for temperature effects on the isotopic composition of precipitation.