The Characteristic Of Drought In Jiangsu Province And Its Influence Factor Research

Based on the climate data from 1961 to 2004 years in the whole province ofJiangsu, introduced Palmer drought severity index (PDSI), compared and analysedseveral commonly used meteorological drought index, proved the rationality of PDSIindex, the article sets up regional PDSI index suitable for the whole province ofJiangsu, then discussed the characteristic of distribution and time of PDSI index inyear, four seasons of Jiangsu Province in detail, analyzed the relation of PDSI indexfield between north Pacific Ocean SSTA field and 500hPa height anomaly field. Mycontribution is: (1)Because of the time factor to consider, the PDSI index is betterreflecting the evolution of drought and flood than the Z index.(2)Characteristic ofdistribution and time of PDSI index shows:①PDSI index has continuation, generalduration is in above two years. Besides autumn, the variation tendency of averagePDSI index of other seasons keeps the same with annual.②The wavelet analysisindicated that year and spring and summer and winter has consistent oscillationperiods, displayed 14～15 years periodic oscillation, but the autumn duration ofoscillation obvious was different, before the 80's intermediate stages was 11 yearabout periodic oscillation, after the 80's intermediate stages were 13 year and 9 yearabout periodic oscillation.③The sensitive area exceptionally responds by the PDSIindex has divided 3 regions, namely Jianghuai area, Sunan area and Huaibei area.Besides spring, various regions RLV center region basic superposition. (3)Analysisindicate with SSTA field of north Pacific Ocean:①The 1st modal PDSI indexdistributed is negative correlation, but the SSTA field positive and negativecorrelation region obvious is different, the essential area mainly concentrates inMarshall islands, southeast in the Hawaiian Islands, the date main island as well asthe equator eastern part nearby and so on.②In model drought and moist year, themain key district lies in east and Eastern Pacific of the equator of island of Japan.③Regardless of the annual mean sea field, or the spring, the summer and the winter sea field, there is a common characteristic: The equator sea of Eastern Pacific indrought year is negative departure, in model moist year for positive departure. But inautumn, it is all negative both drought year and moist year. (4)Analysis indicate with500hPa height field:①The 1st modal PDSI index distributed is negative correlationin autumn and is positive correlation in year and others season. The field positive andnegative correlation region obvious is different in 500hPa height field, the essentialarea mainly concentrates in the date main island, Bering Strait, Siberia nearby and soon.②The year positive and negative departure is smaller, the four seasons positiveand negative departure is bigger. The 500hPa height field unusual area is mainlylocated in Europe and Asia the high latitude, North Pacific Ocean's north as well asNorth America.③The circulation difference also displays in China's eastern part seaarea subtropics strong or weak, the position north or south. In drought year,subtropics often intensity stronger, position towards the north, on the contrary, inmoist year, subtropics then intensity weaker, also the position is towards the south.(5)The earlier period May SSTA field, highly the field summer precipitation has thevery good forecast significance to Jiangsu Province.