摘要
利用1954~2000年中国160站的资料,通过计算趋势系数等现代统计诊断方法,研究了中国年、季、月雨日的时、空特征和气候变化。指出,中国年雨日已经明显减少,而且雨日的减少比降水量的减少明显得多,平均每10年减少雨日3.8天。各季的雨日都是负趋势;季雨日平均每10年减少1天左右。夏季雨日减少最明显(统计检验最显著),秋季雨日减少最多(雨日减少天数多)。雨日长期趋势变化有明显的空间变化,东北、华北、西南区的雨日减少是最多的,这些地区的雨日每10年减少7~10天。雨日的长期趋势变化与降水量的长期变化并不完全一致。雨日的负趋势与降水的负趋势比较,不但范围广,而且强度大(负趋势绝对值大)。中国年降水量明显的负趋势仅位于华北(34°N^38°N,109°E^122°E),而雨日减少最多的地区是东北、华北、西南,范围比降水量大得多。季雨日的长期变化与季降水量的长期变化的差别很大。中国没有一个季节、一个测站的雨日有明显的正趋势变化,但是,降水量仅在秋季是大范围的负趋势,夏季降水量有些测站是明显正趋势,冬季降水量只是小范围的负趋势(冬季的降水量在增加),在冬季,东北仅是很小范围的降水量在减少,而雨日是大范围的明显减少。
There have been many studies on climatic changes in rainfall and droughts/floods, however, study on climatic changes in wet days has been rarely seen. The wet day number of a place is associated with rainfall in the place, but differs from the rainfall. The existing studies show that changes in wet day number differ from those in rainfall. It is necessary to study changes in wet day number, especially to study the difference between them, under the global warming. Up to now, study on climatic changes in wet days nation-wide has not been seen. The climatic change of wet days and the spatial/temporal features of annual, seasonal, and monthly wet days in China are investigated in the context of the observational data at 160 stations during the period of 1954 - 2000 by using modern statistical diagnostic methods such as the computation of trend coefficients. It is pointed out that the annual wet days have declined at a mean rate of 3. 8 days per decade, and the decline of wet days is more obvious than that of rainfall. The temporal trends of seasonal wet days are all negative with a mean reduction rate of one day per decade. The reduction of summer wet days is most remarkable （most statistically significant）, and the reduction of autumn wet days is the largest in magnitude. As far as the spatial change of the secular trend variation of annual wet days is concerned, the reduction of annual wet days is the largest in Northeast China, North China and Southwest China, where the reduction rate is 7 - 10 days per decade. The secular trend variation of wet clays does not completely accord with that of rainfall. The negative trend of annual wet days not only covers a larger area than the negative trend of rainfall, but its intensity is also larger, i. e., the absolute value of the negative trend is larger. The distinct negative trend of annual rainfall lies only in North China within （34°N - 38°N, 109°E- 122°E）, while the largest reduction of annual wet days covers Northeast China, North China, Southwest China, which is a larger area than North China. The secular trend variation of seasonal wet days differs greatly from that of seasonal rainfall. The seasonal wet days do not show an obviously positive trend in a single season at a single station. However, the seasonal rainfall shows a negative trend only in autumn over a large-scale area, but an evident positive trend in summer at some stations. In winter, the seasonal rainfall shows a negative trend only over a small area （the winter precipitation is increasing in China）. In Northeast China, the winter rainfall is reducing only over a small area, but the wet day is reducing evidently over a large-scale area.
出处
《大气科学》
CSCD
北大核心
2006年第1期162-170,共9页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40275028
90411008
关键词
雨日
降水量
气候变化
趋势系数
wet day, rainfall, climatic change, trend coefficient
