Title: Spatial and temporal characteristics of winter drought/flood in southwest China and correlation with Arctic Oscillation
Abstract: Based on monthly rainfall data of 32 stations in southwest China from National Climate Center and the National Center for Environmental Prediction/National Center for Atmospheric Research(NCEP/NCAR) reanalysis monthly data from 1951 to 2010,the spatial and temporal characteristics of wintertime rainfall anomalies in southwest China,and the relationships between those and the Arctic Oscillation(AO) are investigated using precipitation Z indices,Molet wavelet analysis,and Singular value decomposition(SVD).Precipitation Z indices method is used to determine grades of drought and more-rainfall events according to wintertime rainfall.The main results show that in the southeast of southwest China,the wintertime rainfall and frequency of more-rainfall events and drought events are larger than those in the northwest,more than half of the recent 60 years are anomalous rainfall years, drought events are less than the more-rainfall events.The more-rainfall events are apt to occur in southern Sichuan, Yunnan,Guizhou and Guangxi.However,Chongqing,southwestern Yunnan,eastern Guizhou and Sichuan Basin is easy to be influenced by drought events,the probability of occurrence of extreme drought is also higher,and the extreme weather is becoming more and more frequent.Z indices in winter show interannual and interdecadal variability with significant 12 yr and 8 yr periods.In recent years Z indices are at negative phase with less wintertime rainfall and more frequent drought events.There is a strong relationship between AO and the wintertime rainfall in southwest China,when the AO is stronger(weaker),anomalous cyclone(anticyclone) occurs over the Bay of Bengal, and the southwest China is controlled by anomalous warm wet(cold dry) flow from the southwest(northwest) and the water vapor is more(less).Meanwhile the East Asia winter monsoon is weaker(stronger) and more westwards (eastwards) than usual,there is ascending(descending) movement at the level of 500 hPa.The rainfall is more(less) in southwest China.
Publication Year: 2012
Publication Date: 2012-01-01
Language: en
Type: article
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Cited By Count: 2
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