ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Persistent drought events cross the winter and spring in Yunnan and its standard definition
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Abstract:
The persistent drought event cross the winter and spring in Yunnan (YN-WSPDE) have a significant impact on the planting of major autumn crops and the safety of people"s life and property, and it is of great scientific significance for meteorological disaster prevention and reduction to investigate the change and cause of this events. As a fundamental part of the research on YN-WSPDE, how to define the YN-WSPDE standard is studied based on daily precipitation and temperature observation data of 125 stations in Yunnan from 1961 to 2024, as well as the NCEP/NCAR daily reanalysis atmospheric circulation data during the same period. By analyzing the spatiotemporal characteristics of drought in winter and spring in Yunnan, it was found that the drought distribution in Yunnan is characterized by less in the east and more in the west, and more in the north and less in the south. The regions with the highest drought occurrence are mainly concentrated in the eastern part of northwest Yunnan, including Lijiang, Dali, and northern Chuxiong, while the southern parts of Honghe and Xishuangbanna have less drought occurrence. The WSPDEs standard for single station and provincial region in Yunnan are defined as: the station standard refers to the occurrence of light or above level drought in both winter and spring in a year, with moderate or above level drought occurring in one of the seasons. When 25 stations (1/5 of the total number of stations in the Yunnan) experience the WSPDE in a year, and the average precipitation anomaly percentage in both winter and spring is ≤-10%, it is defined as a WSPDE in provincial area. Preliminary analysis results show that the continuously anomalous geopotential height difference at 500-hPa between the north and south in the Eastern of East Asia, as well as anomalous anticyclone at 700-hPa over the Bay of Bengal basin, have a significant impact on the YN-WSPDE.
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Project Supported:
supported by Yunnan Fundamental Research Program, 202501BC070001
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