Camille Risi, University Of Colorado At Boulder
David Noone, University Of Colorado At Boulder
John Worden, California Institute of Technology
Christian Frankenberg, California Institute of Technology
Gabriele Stiller, IMK-A-SF, Karlsruhe Institute of Technology
Michael Kiefer, IMK-A-SF, Karlsruhe Institute of Technology
Bernd Funke, Instituto de Astrofísica de Andalucía
Kaley Walker, University of Toronto
Peter Bernath, University of York
Matthias Schneider, IMK-A-SF, Karlsruhe Institute of Technology
Debra Wunch, California Institute of Technology
Vanessa Sherlock, National Institute of Water and Atmospheric Research, New Zealand
Nicholas M. Deutscher, University of WollongongFollow
David W. Griffith, University of WollongongFollow
Paul O. Wennberg, California Institute of Technology
Kimberly Strong, University of Toronto
Dan Smale, National Institute of Water and Atmospheric Research, New Zealand
Emmanuel Mahieu, Institute of Astrophysics and Geophysics
Sabine Barthlott, Institute for Meteorology and Climate Research
Frank Hase, IMK-A-SF, Karlsruhe Institute of Technology
Omar Garcia, Izana Atmospheric Research Centre
Justus Notholt, University of Bremen
Thorsten Warneke, University of Bremen
Geoffrey Toon, California Institute of Technology
David Sayres, Harvard University
Sandrine Bony, Cnrs, Paris
Jeonghoon Lee, California Institute of Technology
Derek Brown, University of Colorado at Boulder
Ryu Uemura, University of the Ryukyus
Christophe Sturm, Stockholm University



Publication Details

Risi, C., Noone, D., Worden, J., Frankenberg, C., Stiller, G., Kiefer, M., Funke, B., Walker, K., Bernath, P., Schneider, M., Wunch, D., Sherlock, V., Deutscher, N. M., Griffith, D. W., Wennberg, P. O., Strong, K., Smale, D., Mahieu, E., Barthlott, S., Hase, F., Garcia, O., Notholt, J., Warneke, T., Toon, G., Sayres, D., Bony, S., Lee, J., Brown, D., Uemura, R. & Sturm, C. (2012). Process-evaluation of tropospheric humidity simulated by general circulation models using water vapor isotopologues: 1. comparison between models and observations. Journal of Geophysical Research, 117 (D5), 1-26.


[1] The goal of this study is to determine how H2O and HDO measurements in water vapor can be used to detect and diagnose biases in the representation of processes controlling tropospheric humidity in atmospheric general circulation models (GCMs). We analyze a large number of isotopic data sets (four satellite, sixteen ground-based remote-sensing, five surface in situ and three aircraft data sets) that are sensitive to different altitudes throughout the free troposphere. Despite significant differences between data sets, we identify some observed HDO/H2O characteristics that are robust across data sets and that can be used to evaluate models. We evaluate the isotopic GCM LMDZ, accounting for the effects of spatiotemporal sampling and instrument sensitivity. We find that LMDZ reproduces the spatial patterns in the lower and mid troposphere remarkably well. However, it underestimates the amplitude of seasonal variations in isotopic composition at all levels in the subtropics and in midlatitudes, and this bias is consistent across all data sets. LMDZ also underestimates the observed meridional isotopic gradient and the contrast between dry and convective tropical regions compared to satellite data sets. Comparison with six other isotope-enabled GCMs from the SWING2 project shows that biases exhibited by LMDZ are common to all models. The SWING2 GCMs show a very large spread in isotopic behavior that is not obviously related to that of humidity, suggesting water vapor isotopic measurements could be used to expose model shortcomings. In a companion paper, the isotopic differences between models are interpreted in terms of biases in the representation of processes controlling humidity.



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