河南夏季高温气候特征及500 hPa环流型

对河南省40个代表站1961～2005年45年夏季大于等于35℃高温日数进行经验正交函数(EOF)展开分析。方差累积贡献率和空间分布特征显示,前3个典型场基本能反映河南夏季高温日数分布的主要特征,前3个模态的累积方差贡献率达85%,据此得出河南夏季大于等于35℃高温日数的时空分布类型:全省一致型、西北—东南差异型和西南—东北差异型。第1模态对应的时间系数序列的变化幅度最大,第2模态对应的时间系数序列的变化幅度比前一个时间序列要小,第1模态的时间系数演变显示,河南夏季高温日数平均呈减少的趋势,且存在2～4年、8～14年的周期变化,目前河南夏季高温日数正处于偏多的时段。应用逐日20:00500hPa ECMWF北半球格点资料,对1991～2005年15年河南典型的大面积持续高温下的环流形势进行普查、分类,分别求各种类型下的环流平均场,从而得到河南省高温的两种环流型,即贝加尔湖高压型和副热带高压型。

Temporal and Spatial Characteristics and Conceptual Model of Summer High Temperature Weather in Henan

The high temperature days in 40 stations in Henna Province from 1961 to 2005 are analyzed using the EOF method.The accumulative variance contribution ratio and spatial distribution indicate that the first three modes can represent the main distribution of summer high temperature days in Henan,since their accumulative contribution reaches to 85%.The temporal and spatial types of high temperature days in Henan summer can be divided into three patterns:uniform,NW-SE difference and SW-NE difference modes.The time coefficient series of the first mode varies most obviously,and the second one varies less.The time series of the first mode shows that the number of summer high temperature days in Henan has a decline with the periods being 2 to 4 years and 8 to 14 years,and the present is in a period of more-than-normal high temperature days.By use of the daily ECMWF grid data in the Northern Hemisphere at 20:00 at 500 hPa,the circulation patterns from 1991 to 2005,when there occurred large-area persistent high temperature weather,are examined.The two synoptic conceptual models of summer high temperature in Henan are constructed:Baikal high and subtropical high modes.