4B.6
Lag of the atmosphere-land system in the seasonal cycle of monsoons
Brian E. Mapes, NOAA/ERL/CDC, Boulder, CO; and P. Liu
The atmosphere and land subsystems of the monsoons have relatively short response times compared to the ocean. However, these response times are still finite, such that the monsoons are not in equilibrium with the evolving seasonal cycles of insolation and SST. To elucidate this disequilibrium, a land-atmosphere GCM has been utilized. The model is run both in a control run with the ordinary climatological seasonal cycle of SST and insolation, and in quasi-perpetual runs with the SST and insolation held constant for 5 days corresponding to each calendar date. The difference between calendrical climatologies for these two types of integration indicates the magnitude and sense of land+atmosphere disequilibrium. The principal disequilibrium of the Asian monsoon involves onset in south Asia. In contrast, the principal disequilibrium of the North American summer monsoon involves the midsummer drought. .
Session 4B, Monsoon II
Monday, 3 May 2004, 3:45 PM-5:15 PM, Napoleon I Room
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