【作者】 李玲雯；

【导师】 孙卫国；

【作者基本信息】 南京信息工程大学 ， 城市气象学， 2012， 硕士

【摘要】 本文采用1961～2010年重庆33个气象站和三峡库区所涉及的湖北省12个站点的逐日降水量资料、NCEP/NCAR逐月再分析资料、74项环流指数资料和海表温度资料,利用Mann-Kendall方法、小波变换、合成分析、EOF变换、交叉小波等方法,对重庆市降水变化及其原因进行了分析。结果表明：(1)重庆地区年降水量、降水日数、集中期都呈减少趋势,集中度呈增加趋势：年降水量与集中度和集中期的分布存在正相关性,各极端降水指数趋势系数的空间分布具有较好的一致性。(2)重庆地区降水异常与大气环流异常密切相关：对流层中低层风场在重庆地区多水年和少水年期间呈现完全不同的特征；重庆降水偏多的年份,重庆及长江以南地区经向水汽输送主要受南风水汽输送控制,纬向水汽输送以异常西风水汽输送为主。(3)重庆降水变化与天气系统关系密切,年降水量与副高脊线位置变化存在显著的负相关,与东亚夏季风存在负相关性；北太平洋海表温度与重庆降水有密切联系。(4)重庆主城区年降水量变化呈增加趋势,与重庆地区的区域平均趋势相反,无论是年还是四季,重庆主城区出现旱涝的频率都较高。(5)三峡库区年降水量、降水集中度和集中期具有明显不同的年际、年代际特征,降水集中度与降水量的周期振荡较为一致。库区蓄水后,年降水量和集中度较蓄水前减小,集中期较蓄水前增大,蓄水后年降水集中度和年降水量在空间分布上一致性较好。分析认为,西伯利亚位势高度偏高,以及西太平洋副热带高压西移是三峡库区降水较集中的大气环流背景；乌拉尔山以东有明显的阻塞高压形势发展以及西太平洋副高偏西、偏南时,重庆地区降水偏多；海温异常对预测次年重庆降水异常具有一定的指示性意义。更多还原

【Abstract】 Based on the daily precipitation data in1961～2006from33stations in Chongqing and from12stations in Hubei Provice, using the analysis methods of Mann-Kendall test, wavelet, synthesis, EOF, correlation and Bivariate Wavelet, the characters of Chongqing precipitation variation and its reasons were studied.The results showed that:(1) From the long-term change, the annual precipitation, rain day and the precipitation concentrated period (PCP) revealed decreasing tendency, while the precipitation concentration degree (PCD) with a weak increase. The distribution of PCD and PCP were positive associated with the annual precipitation.The spatial distribution of indices of extreme precipitation revealed consistency.(2) The precipitation anomaly in Chongqing was closely related to the abnormity of atmospheric circulation.The wind field on the lower troposphere revealed absolutely different characters in more and less precipitation years. In more precipitation years, there was a north wind abnormally moving southward in the zontal water vapor transport, while the meridional water vapor by west wind. The cold flow crossed with the warm flow in Yangtze river basin. It was opposite in less precipitation years.(3) The precipitation anomaly in Chongqing was also closely related to the weather systems. The annual precipitation was negatively associated with the northern boundary of subtropical high and the subtropical high ridge, it also had a positive relationship with the westward ridge spot index. The annual precipitation had a negative relationship with the Asian Summer Monsoon and also associated with the Pacific SST.(4) The annual precipitation of main city zone of Chongqing revealed increasing tendency, which was opposite to the average congdition of the whole aera. No Matter in year or seasons, the occurrence frequency of Droughts and floods are high.(5) The annual precipitation, PCD and PCP displayed obvious different interannual and interdecadal variations in the Three Gorges Reservoir, the periodic oscillations of annual precipitation and PCD were basically consistent with each other. After impound of the Three Gorges Reservoir, less precipitation and lower PCD value displayed comparing with that before impounded, while the concentration period was later. After impounded, the distribution of precipitation and PCD had good consistency while the PCD revealed significant differences.After analyzed, it was known that:When the precipitation in the Three Gorges Reservoir was concentrated, the atmospheric circulation background showed that the anomaly of500hPa geo-potential height field was positive in Siberia and the subtropical high over western Pacific moved westwards. The blocking over the East of Uraland area developed and the subtropical high was west and south when there was less precipitation in Chongqing. The anomaly of sea surface temperature had a indicative significance to forecasting the following year precipitation in Chongqing.更多还原