Evaluation of Tropical Upper Troposphere hydrological Processes derived from ECMWF analyses and Forecast with EOS MLS Measurements

To assess the status of global climate models (GCMs) in simulating upper-tropospheric hydrological processes (using ice water content (IWC), water vapor and temperature etc), a new set of measurements from the Earth Observing System's Microwave Limb Sounder (MLS) are used. Comparisons are made with ECMWF analyses and forecast. For August 2004 to September 2005 monthly values, the spatial agreement between MLS and ECMWF is quite good in particular over oceans, although MLS estimates of IWC are higher by a factor of 2-3 over the Western Pacific, tropical Africa and South America. In particular, for larger values of disagreement occurring over tropical Africa and South America will be discussed. The implications arising from sampling and uncertainties in the observations, the modeled values and their comparison will be discussed. These results demonstrate the potential usefulness of this data set for evaluating GCM performance and guiding development efforts.