87th AMS Annual Meeting

Tuesday, 16 January 2007: 3:30 PM
Simulated change of drought over Asia under global warming scenario
214B (Henry B. Gonzalez Convention Center)
Do-Woo Kim, Pukyung National University, Busan, South Korea; and H. R. Byun and S. U. Han
The impact of global warming on the East Asian drought is analyzed using daily precipitation data of 10-coupled atmosphere-ocean general circulation model (AOGCM) simulations under the SRES A1B scenario at the end of the twenty-first century. The Effective Drought Index (EDI; Byun and Wilhite 1999) is applied to determine the severity of drought.

The rainy periods over East Asia (100E-140E, 10N-50N) are induced by different mechanisms along the latitude. The rainy period over South-East Asia (100E-140E, 10N-30N; SEA) is characterized by summer monsoon which onsets in early May and withdraws in late October. Over North-East Asia (100E-140E, 30N-50N; NEA), the rainy periods can be divided by two periods. One is the Spring Rainy Period (SRP) from March to May and another is the summer monsoon which onsets and withdraws within summer (JJA).

In the future, the most remarkable features are the enhanced precipitation over NEA and reduction in precipitation over SEA during spring. It means the enhanced SRP and late onset of Southeast Asian summer monsoon (SEASM). Another feature is the increased precipitation over both regions during summer (JJA).

We have investigated on how to respond to the drought with the changed precipitation in future. Results show the district decrease of drought days over NEA and the increase over SEA during spring. Over SEA, the maximum increase of drought days appears in early summer by the accumulated reduction of precipitation during spring. In spite of the increased precipitation during summer and autumn, the trend of increasing drought days is sustained. It seems to be related to the enhanced precipitation variability resulted from enhanced evaporation variability over warmer tropical Pacific Ocean. Over NEA, in contrast to over SEA, the drought days are decreased for all seasons.

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