上海高温和低温气候变化特征及其影响因素

基于上海11个气象站逐日最高、最低气温、降水资料和西太平洋副热带高压(简称副高,下同)环流指数,分析了上海夏季高温和冬季低温的气候变化特征及其影响因素.结果表明,1873～2007年,上海高温日数表现为少-多-少-多的年代际变化,低温日数则表现为多-少的年代际变化.2001～2007年,上海年均高温日数、各级高温过程数和高温过程日数都最多,低温日数、低温过程数和低温过程日数都最少.1960～2007年,上海每年高温日数与当年夏季副高面积和强度指数显著正相关,低温日数与当年冬季副高面积和强度指数显著负相关.降水对上海极端气温有一定的缓解作用,上海高温日数与夏季降水量弱显著负相关,低温日数与冬季降水量显著负相关.上海高温过程数受城市化影响较大,其时间变化具有明显的城郊差异,低温过程数则受城市化影响较小.

CLIMATIC CHARACTERISTICS OF HIGH AND LOW TEMPERATURE AND ITS EFFECTING FACTORS IN SHANGHAI

Based on the daily maximum and minimum temperature,monthly precipitation from 11 meteorological stations in Shanghai and the West Pacific subtropical high area and intensity index,the climatic characteristics and its effecting factors of high and low temperature in Shanghai were analyzed.From 1873 to 2007,the high temperature days showed less-more-less-more inter-decadal variability,and the low temperature days showed more-less inter-decadal variability.In the period from 2001 to 2007,Shanghai had the most high temperature days and the least low temperature days,the most numbers and days of high temperature process and the least numbers and days of low temperature process in the past 135 years.In the period from 1960 to 2007,annual high temperature days were positively correlated with the summer area and intensity index of West Pacific subtropical high significantly.Annual low temperature days were negatively correlated with the winter area and intensity index of West Pacific subtropical high significantly.Precipitation has some alleviation for the extreme temperature.Annual high temperature days were negatively correlated with the summer precipitation in Shanghai,and annual low temperature days were also negatively correlated with the winter precipitation from 1960 to 2007.Urbanization has more influence on the high temperature process than it on the low temperature process.The difference of high temperature process between urban and suburb area was obvious,but the difference of low temperature process was less.