青南高原近30a雪灾的时空分布特征

本文选用青海南部高原13个气象站的1971-2000年的春季(3-5月)和冬季(10-2月)降水资料,进行经验正交函数(EOF)展开分析。结果发现对青南地区13站春季和冬季的降水资料经验正交函数(EOF)展开,春季所得的前三个模态和冬季的前两个模态都能很好地表示青南高原春冬季雪灾的空间分布特征;通过对春冬季第一模态的时间系数的分析,得出青南高原春冬季雪灾的主要周期:青南春季雪灾存在一个准4和准8年的主周期;青南冬季雪灾存在一个准2、5年和15年左右的主周期。从统计资料中可得出青南高原春季发生大雪灾的次数比冬季多。

Temporal and Spatial Variations of Snow Disaster in the Southern Qinghai Plateau in Recent 30 Years

The spring's precipitation(March~May) and the winter's precipitation (October ~February) time series of 13 weather stations of the Southern Qinghai Plateau in Recent 30 Years(form 1971 to 2000)are respectively analyzed by the EOF method.At the same timethe spatial distribution and corresponding temporal variation of the main EOF modes are discussed.It is found that the fore-three models of spring's precipitation have a good spatial property,and the fore-two models of winter's precipitation also have a good spatial property.The time coefficients of the first models of spring's and winter's precipitation are analyzed by the Morlet wavelet and the entropy spectrum analysis.Results show that the snow disaster of spring inthe southern Qinghai Plateau has 4 and 8-year periods and the snow disaster of winter inthe Southern Qinghai Plateauhas 2,5 or 15-year periods.From the statistics data,the numbers of the heavy snow disasters in spring are more than that in winter.