摘要
(1 )分析得到勤试验站 1 3个观测指标中的 1 45个统计项中的前 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 6 0～ 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 ;年大风日数呈波浪式上升 ;年最大风速有增无减 ;8月降水量相对稳定。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 ;年平均最高气温、年平均地温和 7月份极端最高气温与年平均气温的多年分布有较大相似性 ;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 6 0年代到 80年代中期气候逐步改善 ,与当地 6 0、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。
The changing characteristics of maximum loading factors of the first 6 principal components in Principal Component Analysis (PCA) on 145 statistical items of 13 observed indexes were:annual sunshine hours decreased gradually during the 1970s and the 1980s,but it has increased evidently since the begining of the 1990s:and there was a decreasing trend in annual average temperature from the 1960s to the 1980s,but it has rised evidently since the 1990s;average wind velocity in October gradually reduced from the mid 1970 to the mid 1980s,then increased;the days of annual strong wind increased wavily;annual maximum wind velocity constantly lifted the change of rainfall in August.The local climatic conditions had a good developing trend before the middle of 1980s,but since the late 1980s it has been deteriortated.(2)The change of annual sandstorm days was similar to annual sunshine hours;the distributing characters of annual maximum temperature,annual average ground temperature and maximum temperature in July were similar to annual average temperature;the distributing character of annual strong wind days was similar to the average wind velocity in October.(3)The climatic condition had shown some improvements from the mid 1960s to the mid 1980s due to trees planted and shrubs in large scale since the 1960s,and it was deteriorating since the late 1980s concerned with the drop of groud water table and died off of man made sand fix forest.
出处
《气象》
CSCD
北大核心
2000年第5期48-51,共4页
Meteorological Monthly
