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摘要
The General Circulation Models(GCMs)are not easy to reproduce the temporal-spatial patterns of precipitation in Qinghai-Tibetan Plateau(QTP)due to its current coarse resolution. To meet the requirement of high-resolution datasets for many applications, dynamical downscaling modeling(DDM)has been developed and proven to be an essential tool for achieving high-resolution climate data in study domain. DDM using a regional climate model WRF driven by a general circulation model CCSM4 has been adopted, the downscaling results for the historical period(1998-2005)are evaluated for the wet season total precipitation rate and convective precipitation fraction over the QTP. The variations of total precipitation, stratiform precipitation and convective precipitation projected by CCSM4 and WRF are also analyzed. The results show that, compared with the coarse-resolution forcing, the DDM is able to better capture the spatial and elevation patterns of wet season total precipitation rate and convective precipitation fraction over the QTP in 1998-2005. Compared with the uniform increase in CCSM, WRF also projects increasing precipitation for the future period 2070-2099 under the two Representative Concentration Pathway(RCP)scenarios 4.5 and 8.5, with an increase in the northern QTP and a decrease in the southern QTP, the increase of total precipitation in northern QTP basically resulted from the increased convective precipitation, while the reduction of stratiform precipitation was the main reason for the reduced total precipitation in the southern QTP. Overall, regarding the entire TP, the contribution of increased convective precipitation was far larger than reduced stratiform precipitation to the total precipitation, and which was predominantly seen at the altitude below 4000 m.
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