Tuesday, 13 January 2009
Comparisons of Satellites Liquid Water Estimates with ECMWF and GMAO Analyses, 20th Century IPCC AR4 Climate Simulations, and GCM Simulations
Hall 5 (Phoenix Convention Center)
To assess the current fidelity of general circulation models (GCMs) in simulating cloud liquid water, liquid water path (LWP) data from several passive satellite retrievals and the vertically-resolved liquid water content (LWC) data from the CloudSat radar retrievals are used. Comparisons are made with ECMWF and GMAO MERRA analyses, GCM simulations utilized in the IPCC 4th Assessment, and four additional GCM simulations, including one based on different types of multi-scale modeling frameworks. There is considerable disagreement amongst the observed LWP estimates as well as amongst the modeled values. The LWP from GCMs are much larger than the observed estimates and two analyses. Better agreement is found between non-precipitating conditions of CloudSat LWP and the values from two analyses. Large peak values are only evident in the total CloudSat LWP over the boundary-layer stratocumulus cloud regions, possibly associated with drizzle detected at the surface. There are degrees of differences in the vertical LWC distributions exhibited by the GCMs, analyses and CloudSat retrievals. The vertical extent of LWC in the Tropics from the GCMs and analyses values are greater than estimated from CloudSat. The issues of representing cloud liquid and precipitation are discussed in the context of making comparisons between satellites derived estimates and the models.
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