民勤西沙窝生态气候变化特征分析

(1 ) 1 3个指标的 1 45个统计项前 6个主成分最大载荷因子的多年变化特征是 :年日照时数 70— 80年代持续下降 ;年平均气温 60— 80年代下降 ,90年代以后显著增高 ;1 0月份平均风速 70年代中期至 80年代中期下降 ,之后增大 ;年大风日数波浪式上升 ;年最大风速有增无减 ;8月降水相对稳定。当地的气候环境在 80年代中期以前朝良性方向发展 ,80年代中期以来进一步恶化。 (2 )年沙尘暴日数的多年变化特征与年日照时数有较大的相似性 ;年平均最高温、年平均地温和 7月份极高温与年平均气温的多年分布有较大的相似性 ;年大风日数和 1 0月平均风速多年分布有较大相似性。 (3 )从 60年代到 80年代中期气候逐步改善 ,与当地 60、70年代大面积营造防风固沙林密切相关 ;80年代中期以来气候环境迅速恶化 ,与 80年代以来大面积开荒超采地下水 ,大面积人工固沙林衰败死亡有着不可分割的联系。

Analyses on Changing Characteristics of Climate in Xishawo Desert of Mingqin

the Change Characteristics of Maximum loading factors of first 6 principal components which are in 145 statistical items of 13 observed indexes in principal Component Analysis (PCA) were:there was a drop in annual sunshine hours from 1970’s to 1980’s,but it has increased evidently since the begining of 1990’s; and there was a decreasing trend in annual average temperature from 1960’s to 1980’s ,but it has risen evidently since 1990’s;average wind valocity on october gradually reduced from middle of 1970’s to middle of 1980’s then increased;the days of annual strong wind has increased in waves; annual Maxi mum wind votocity constantly lift; the rainfall on August was even. the local climatic conditiom had a good developing frend before the middle of 1980’s but since the late of 1980’s it has deteriorated. (2)The change of days of annual sand-dust storm was similar to annual sunshine hours; the distributing characters of annual maxmum temperature, annual average ground temperature and Maximum temperature on July were similar to that of annual average temprature; The distribuing character of annual strong wind days was similar to that of average wind volocity on october. (3)the climatic condition had improved from 1960’s middle to 1980’s middle, which related to planting trees and shrubs in large scale since 1960’s. climate have deterioratend since late of 1980’s, which concerned with the drop of ground water table and death of man-made sand-fixed forest.