TY - JOUR
T1 - Process-evaluation of tropospheric humidity simulated by general circulation models using water vapor isotopologues
T2 - 1. Comparison between models and observations
AU - Risi, Camille
AU - Noone, David
AU - Worden, John
AU - Frankenberg, Christian
AU - Stiller, Gabriele
AU - Kiefer, Michael
AU - Funke, Bernd
AU - Walker, Kaley
AU - Bernath, Peter
AU - Schneider, Matthias
AU - Wunch, Debra
AU - Sherlock, Vanessa
AU - Deutscher, Nicholas
AU - Griffith, David
AU - Wennberg, Paul O.
AU - Strong, Kimberly
AU - Smale, Dan
AU - Mahieu, Emmanuel
AU - Barthlott, Sabine
AU - Hase, Frank
AU - García, Omaira
AU - Notholt, Justus
AU - Warneke, Thorsten
AU - Toon, Geoffrey
AU - Sayres, David
AU - Bony, Sandrine
AU - Lee, Jeonghoon
AU - Brown, Derek
AU - Uemura, Ryu
AU - Sturm, Christophe
PY - 2012/3/16
Y1 - 2012/3/16
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=84863293787&partnerID=8YFLogxK
U2 - 10.1029/2011JD016621
DO - 10.1029/2011JD016621
M3 - Article
AN - SCOPUS:84863293787
SN - 0148-0227
VL - 117
JO - Journal of Geophysical Research C: Oceans
JF - Journal of Geophysical Research C: Oceans
IS - 5
M1 - D05303
ER -