【摘要】 选取1980-2015年中国632个气象站的降水资料,从中筛选出江淮地区7次强降水事件,运用经验正交函数分解(EOF分析)和合成、相关方法分析了强降水的空间分布及其对应的环流特征。结果表明:在第一模态场(方差贡献率为22. 4%)中,该地区南北部降水量呈反相关关系,我国东部地区的降水形态从北到南为"-+-"的交替分布形态。在第二模态场(方差贡献率为17. 8%)中,江淮地区东南部与中西部地区的降水量呈现反相关关系,中国东部地区的降水形态从北到南为"-+"的偶极分布形态。500 h Pa平均高度场上,中纬度地区巴尔喀什湖及东北地区为两槽一脊型;第一模态时间系数与500 h Pa高度的相关场上,东北地区西部及内蒙古东部的等高线分布与江淮地区降水有较明显的负相关关系。850 h Pa高度,江淮地区主要为南风;相关场上,东北地区南部到华北地区的v→风场与江淮地区降水之间有较明显的负相关。表明当中纬度地区巴尔喀什湖及东北地区的槽加强时,华北地区北风与江淮地区南风会合,冷暖空气交汇于江淮,降水较多,呈第一模态降水的分布型。更多还原

【Abstract】 Based on daily precipitation data from 1980 to 2015 for 632 meteorological observational stations in China,7 heavy rainfall events in Jianghuai region were selected. The spatial distribution and circulation pattern of these 7 heavy rainfall events in Jianghuai region were calculated using the Empirical Orthogonal Function( EOF)expansion and synthesis. The leading mode of Empirical Orthogonal Function( EOF)( can explain 22. 4% of the total variance) manifests when heavy rainfall event occurs in Jianghuai region,precipitations in northern part and in southern part of Jianghuai region showinverse relationship,the precipitation pattern shows"-+-"distribution from north to south over Eastern China. Precipitation anomalies of the second EOF mode( can explain 17. 8% of the total variance) shows that when heavy rainfall event occurs in Jianghuai region,precipitation in southeastern part and in central and western parts of Jianghuai region showinverse relationship,the precipitation pattern form north to south over eastern China is "-+"dipole distributions. The 500 hPa mean geopotential height field shows that,circulation feature shows Two-trough and One-ridge from Balkhash Lake to Northeast China in mid-latitude region. Using the principal components of the first EOF mode of the heavy rainfall events in Jianghuai region and the 500 hPa geopotential height field to get correlation coefficients. The result shows that,the contour distribution in the western part of Northeast China and the contour distribution in the eastern part of Inner Mongolia showinverse correlation with the precipitation in Jianghuai region. 850 hPa’s wind blows northward over Jianghuai region. In the correlation coefficients field,the v-direction wind field from the southern part of Northeast China to North China shows inverse correlation with the precipitation in Jianghuai region. The result shows that,when the trough in Balkhash Lake and the trough in Northeast China get stronger,north wind over North China assembles with south wind over Jianghuai region. Meanwhile,confluence of cold air and warm air leading to more precipitation over Jianghuai region. Precipitation pattern is of the first EOF mode.更多还原