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《Journal of Arid Meteorology》 2017-04
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Numerical Simulation of an Extreme Drought Event and Its Wave-Flow Action Analysis in Spring of 1995 in Northwest China

REN Yulong;LI Yaohui;DUAN Haixia;SONG Linlin;Institute of Arid Meteorology,CMA,Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province,Key Laboratory of Arid Climate Change and Disaster Reduction of CMA;  
The numerical simulation and diagnosis of extreme drought events is an important method to test the performance of regional climate model and study drought mechanism. The extreme drought event occurring in spring of 1995 in Northwest China was simulated by Reg CM4 model,firstly. Based on the NCEP reanalysis data and monthly precipitation data from 137 weather stations in Northwest China,the effect of the extreme drought event simulated by Reg CM4 model was tested. And on this basis the formation mechanism of the extreme drought event was analyzed by using wave-flow theory. The results show that Reg CM4 model could simulate the spatial distribution of drought grades of the extreme drought event better,but the errors between the simulated and the observed were different in different areas,and it could also accurately simulate the main influence climate system,which indicated that the model had a good reappearance ability to the extreme drought event. The downward flow in Northwest China enhanced due to the stronger Ural mountain high pressure and the Mongolian low pressure in spring of 1995. Meanwhile,the water vapor flux decreased significantly compared with the normal year because the strong westerly airflow in low level impeded the water vapor transport to the region of Northwest China. The analysis of wave-flow theory indicated that there was a wave-train transporting from west to east on 300 h Pa,and the transient wave energy reached the maximum in Ural mountain area in April. The divergent E-P flux caused the enhancement of the westerly jet in the north of the Ural mountain high pressure ridge,which led to the development and maintenance of the Ural mountain high pressure,thus caused the extreme drought event.
【Fund】: 公益性行业(气象)科研重大专项(GYHY201506001);; 甘肃省气象局重点科研项目专项(GSMAZd2017-10)共同资助
【CateGory Index】: P426.616
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