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。

NATURAL ENVIRONMENT QUALITY EVALUATION OF WATER SOURCE AREA OF THE MIDDLE ROUTE OF SOUTH-TO-NORTH WATER TRANSFER

South-to-North Water Diversion Project receiving the whole society attention is a strategic foundation subject in our country.Study of the natural environment quality of its water source area is the foundation for South-to-North project smooth implementation,it also has the significant reference value and the practice significance.This article took Shaanxi water source area of the Middle Route of South-to-North Water Transfer as the object,selected evaluating indicator,utilized the AHP decision analysis method,built up the environmental quality evaluation system hierarchical structure model based on on-the-spot investigation and consultation.Its target weight was revised with information entropy method.And then through fuzzy comprehensive assessment method,combination of qualitative and quantitative analysis,the local natural environment quality synthetic evaluation results were obtained.The evaluation result shows that the natural environment quality of water source area is ordinary,it still requires further improvement.In order to ensure the smooth implementation of South-to-North Water Transfer Project,and promote sustainable development of water resources,it should take effective measures to resolve the existing problems affecting the quality of the environment as soon as possible.