三峡库区局地气候变化

三峡库区地处鄂西和渝东的崇山峻岭中，局地气候受山谷和水体的共同影响，冬暖夏热，降水丰富。利用三峡库区及其周边地区33个气象观测站1961~2006年降水与温度观测资料，对2003年蓄水前后的降水、气温等要素作了时间对比分析，同时分别选取近库区和远库区站点作降水比值和温度差值分析，结果表明近几年库区降水较常年偏少，但降水趋势与西南地区降水年代际变化一致。20世纪90年代之后三峡库区气温有显著上升趋势，蓄水后受水域扩大影响近库地区的气温发生了一定变化，表现出冬季增温效应，夏季有弱降温效应，但总体以增温为主。由于三峡工程局地气候影响是一个复杂、长期的气候调节过程，所给出的结果只是三峡水库蓄水至今3年时间的观测分析结果，同时蓄水前后温度变化还需要更长时间观测分析统计，对水库水域扩大影响造成的局地气候效应有待更多研究方法及模式结果的验证。

REGIONAL CLIMATE CHANGE OVER THREEGORGES RESERVOIR AREA

The world famous“Three Gorges Reservoir (TGR)”is situated on the middle reaches of the Yangtze River.The construction of this reservoir will probably be finished in 2009 when the final water level will reach 175 meter and the reservoir will cover 10 000 km2 of region. No doubt,this huge water body will influence the regional climate to a certain extent.It never occurred such a dramatic intervention in the local environment in the mankind history.Thus the atmosphere problems related to the TGR have attracted a lot of interest from most meteorologists around the world.Based on the rainfall and temperature observation data of 33 stations in the TGR area during the period 1961 to 2006,the climate characteristics of rainfall and temperature changes since the water storage of TGR are analyzed.The rainfall amount and mean temperature before water storage were compared with those after storage,and also the water effect on regional climate was analyzed by rainfall amount ration or temperature difference of near TGR and far TGR observations.Results show a decreasing rainfall trend in the past three years over the TGR area,which is consistent with the climate change over Southwest China.Meanwhile,the expanding water surface area of reservoir seems to have increasing temperature effect in winter and decreasing effect in summer.However,the impacts from TGR are by no means fully understood from 3 year observations,and there is still a lot to be deal with the environment problems by carrying out long time in situ observations and developing more technical analysis in the future.