江苏省近50a气候干湿特征研究

根据江苏省1960—2009年54个气象台站常规气象观测资料,利用Penman-Monteith公式计算了全省各地区50 a的逐日潜在蒸散量,结合逐日降水量,推算出了相对湿润度指数值,并采用国家标准《气象干旱等级》(GB/T20481-2006)中的相对湿润度分级指标对全省干湿状况进行了评估,分析其时空变化特征。研究表明:1)就全年而言,江苏省半干旱区与湿润区各占50%左右的面积,其中淮北、江淮北部、苏北沿海的北部为半干旱区,江淮南部、苏北沿海的南部、沿江、苏南地区为湿润区;2)降水量和潜在蒸散量是影响相对湿润度指数的两个关键因子,降水量的变化对相对湿润度的时空分布起着主导作用,潜在蒸散量起着辅助作用。3)江苏省1 a中冬季的南北气候干湿反差最大、夏季最小,湿润区范围夏季最大、秋季最小,半干旱区范围秋季最大、夏季没有,干旱区范围春季最大、夏季和秋季没有。夏季气候最湿润、春季气候最干燥。4)淮北和苏北沿海地区的相对湿润度指数年变化呈"单峰型",江淮、沿江和苏南地区的年变化呈"双峰型",苏北沿海地区相对湿润度年内变化最大,沿江地区最小。

Arid and moist climate characteristics in Jiangsu Province in recent 50 years

Based on the conventional weather observational data from 54 meteorological stations in Jiangsu Province from 1960 to 2009,the daily potential evapotranspiration at different stations in this province was calculated by Penman-Monteith Equation.Relative moisture index(I_RM),an index reflecting arid and moist climate characteristics,was used to evaluate the arid and moist climate conditions in a region.The daily I_RM values at different stations in the province were computed from the observed precipitation and the calculated evapotranspiration.According to the Chinese Meteorological Drought Grades in the National Standard GB/T20481-2006 of China,the computed I_RM values were classified into three grades and the different statistical parameters of I_RM were used to analyze the arid and moist characteristics in different regions of Jiangsu Province.The research results indicate:1) In a year,the semi-arid area and the moist area occupied a half of the total area in Jiangsu province respectively.Among them,the northern side of the Huaihe River,the north part of the region between the Yangtze River and the Huaihe River and the north part of the coastal region were semi-arid area and the south part between the Yangtze River and the Huaihe River,the south part of the coastal region,the valley of the Yangtze River and the south part of Jiangsu Province were the moist area;2) The precipitation and the potential evapotranspiration in a region were the two key factors influencing the relative moisture index and the climatic dryness and wetness characteristics in the region.The change of precipitation played a dominant role in the tempo-spatial changes of I_RM and the variation of the potential evapotranspiration played an auxiliary effect;3) In winter,there was the most obvious arid and moist contrast between the south and north parts of Jiangsu Province while it was the least in summer.The scope of moist area was largest in summer but it was smallest in autumn.The scope of semi-arid area was largest in autumn but it had no distribution in summer.The scope of arid area was largest in spring but there were no arid area in summer and autumn.The climate in Jiangsu Province was moistest in summer but it was aridest in spring;4) The annual change of I_RM presented a single peak on the north side of the Huaihe River and the coastal region and there were two peaks in the region between the Yangtze River and the Huaihe River,the Valley of the Yangtze River and the south part of Jiangsu Province.The interannual variability of I_RM was largest in the coastal region but it was smallest in the valley of the Yangtze River.