近44 年关中夏季分级雨日及降水量的变化特征

VARIATION CHARACTERISTICS OF SUMMER GRADING RAINY DAYS AND PRECIPITATION IN GUANZHONG IN RECENT 44 YEARS

关键词:  关中 分级雨日 夏季降水 趋势系数 变化特征

Key words:  Guanzhong  rain day grading  summer precipitation  trend coefficient  variation characteristics

摘要:

［目的］通过对关中地区夏季雨日（量）进行分级研究，更深入地了解关中夏季降水变化特征及各级雨日（量）对关中夏季降水变化的贡献大小。［方法］利用1970～2013年关中地区44个气象站逐日降水资料，采用趋势分析法，Mann-Kendall检验，t-检验和GIS技术等方法对关中夏季不同等级雨日和雨量变化特征进行分析。［结果］（1）关中多年平均夏季雨日空间分布均为西多东少，西北部塬区和山区丘陵多于平原，各等级雨日和对应雨量空间分布特征及变化趋势相似。（2）近44年关中夏季总雨日、小雨日（量）和大雨日（量）均呈减少趋势，夏季降雨总量、中雨日（量）和暴雨日（量）均呈增加趋势，但线性变化趋势均不显著。其中小雨日（量）和大雨日（量）分别在1989年和1985年发生突变性减少，中雨日（量）在1978年发生突变增加。（3）单站分析表明关中夏季总雨日除咸阳大部外多数呈负趋势，夏季降雨量除渭南大部外普遍为正趋势。其中大部分站点小雨日（量）和大雨日（量）为负趋势，减少显著的站点分布在宝鸡地区； 中雨日（量）和暴雨日（量）普遍为正趋势。［结论］夏季总雨量的增加主要贡献者是中雨量增加，总雨日减少主要是小雨日减少引起。从长期趋势变化看，关中夏季降水强度有增加趋势。

Abstract:

With the aim of comprehensively understanding the variation characteristics of summer grading rain days and precipitation in Guanzhong and the contribution of the different grading rain days (amounts) to summer rain days(amounts), this paper analyzed the spatial and temporal variation characteristics of summer grading rain days and precipitation based on the data of 44 meteorological stations in Guanzhong during 1970-2013,using the methods of trend analysis, Mann-Kendall test, t-test and GIS technique. The result showed that：(1)The summer rain days in the west were more than the east, and that in the loess platform areas in northwest of Guanzhong and mountainous areas were more than that in the plain. The spatial and temporal variations of each grade rain days and that of precipitation were very similar. (2)Summer total rainy days, light rainy days(amounts) and heavy rainy days (amounts) all showed decreasing trends in recent 44 years. But the linear change trends were not obvious. The light rainy days(amounts) and heavy rain days (amounts) reduced suddenly in 1989 and 1985, respectively. And the moderate rain days(amounts) abruptly changed in 1978.(3) the summer rainy days in most stations had negative trend except Xianyang, while summer precipitation in most stations had positive tendency except Weinan. The light rain days (amounts) and heavy rain days(amounts) in most stations were decreased, and the obvious decrease stations mainly distributed in Baoji. It concluded that the summer total precipitation increased was mainly due to the increase of moderate rain. The reduction of summer rain days was due to the decreased of light rain days. For the long trend, summer precipitation intensity in Guanzhong will be increased.