Changing characteristics of extreme drought in spring and its relationship with circulation factors in Songnen Plain of Heilongjiang Province
Based on the daily precipitation data from March to May at 32 weather stations in the Songnen Plain of Heilongjiang Province from 1961 to 2021 and the atmospheric circulation and sea temperature index data during the same period,the longest consecutive number of days without precipitation(LCDD)was adopted as an indicator of extreme drought in spring.Mathematical statistics methods were used to analyze the spatial distribution character-istics and temporal changes of extreme drought in spring,as well as the effects of atmospheric circulation and sea temperature on LCDD.The results showed that the spring extreme drought in Songnen Plain had a decreasing trend,LCDD changed at a rate of-1.2 d·10a-1,and the interannual oscillation was strong.The interdecadal change showed a decreasing trend in general,the highest in the 1960s,the lowest in the 2000s,and a slight rise in the 2010s.The spring extreme drought in Songnen Plain mutated in 1971,with a total of three main cycles of 28 a,14 a and 6 a.The spatial distribution of LCDD was more in the west and less in the east,with the high value loca-ted in the west of Songnen Plain.From November to March,the Western Pacific Subtropical High Area Index,East Atlantic-West Russia Pattern,the India-Burma Trough Intensity Index,the North American-Atlantic Subtropical High Area Index,the West Pacific 850 hPa Trade Wind Index,and the North American Polar Vortex Intensity In-dex had significant effects on LCDD(P＜0.01).Four leading SST factors,namely,the Kuroshio Current SST In-dex,the Oyashio Current SST Index,the NINO 4 Sea Surface Temperature Anomaly(SSTA)Index and the West Wind Drift Current SST Index had significant effects(P＜0.01).LCDD can be used to characterize the variation of extreme drought in Songnen Plain,and the atmospheric circulation and SST factors in the early period can be used as prediction signals.
spring droughtchanging characteristicsLCDDcirculation factorsSongnen Plain
万方数据
维普
