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Simulation of East Asian monsoon weather and climate using a high-resolution global GCM at GFDL
Ngar-Cheung Lau, NOAA/GFDL, Princeton, NJ
The results from a 20-year integration of a 24-level, finite-volume global atmospheric general circulation model with a horizontal resolution of 0.5 degrees in latitude and 0.625 degrees in longitude are described. Emphasis is placed on the simulation of climatological and weather-scale characteristics associated with the East Asian monsoon.
Several well-known monsoon features are realistically reproduced in the model atmosphere. This family of simulated phenomena include wintertime cold air outbreaks over East Asia, establishment of the upper-level Tibetan Anticyclone in May-June, and near-stepwise poleward migration of the rainbands from southern China to Japan, the Korean Peninsula and northeastern China in May-July. Outstanding synoptic episodes of strong cold surges in winter and intense precipitation activities (Meiyu) over the Yangtze River Basin in summer have been selected for further analysis. These case studies reveal strong interactions between mesoscale weather changes and the broader ambient atmospheric environment. The diagnoses also demonstrate the capability of this global model to simulate the detailed patterns of such small-scale structures as frontal surfaces and low-level jets.
It is also demonstrated that this high-resolution model is capable of generating fine details of precipitation and circulation features in the vicinity of relatively small-scale mountain ranges, as well as over regions with complicated coastlines. The interactions of the monsoon flows with the local terrain yield spatially intricate rainfall patterns in Southeast Asia throughout the annual cycle.
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Session 5, Comparisons between high-resolution regional and global models for studying climate
Thursday, 18 January 2007, 1:30 PM-4:30 PM, 206B
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