1960～1997年新疆北部降水序列的趋势探测

利用非参数统计检验法（Mann-Kendall法）分析了新疆北部地区13个气象台站1961-1997近40年降水序列的趋势。因季节性差异，对1月、4月、7月、10月的降水序列也进行了分析。结果表明，1961-1997年新疆北部地区年降水序列大致存在增加的趋势，但不是很普遍；多数测站的年降水序列无趋势。以4月、10月为代表的春秋季降水量没有趋势存在；在少数测站以1月为代表的冬季降水序列出现了上升趋势，说明1961-1997年间新疆北部冬降水量有一定量的增加；3个测站在以7月以代表的13个夏季降水序列中出现了上升趋势，还有一个测站出现了下降趋势，说明新疆北部地区夏季降水在1961-1997年间有少量的增加，并且降水变化趋势存在一定的地区差异。

Trend Analysis of Precipitation over Northern Xinjiang for the Period 1961-1997

Located in inland and far from ocean, Xinjiang is characterized by its vast deserts. The ecological environment of Xinjiang is extremely fragile owing to the: aridity. Therefore, it is recognized that Xinjiang is a sensitive and affected area to global warming. In recent years, it is found that there is a warming trend corresponding to global warming in this area. In the case of the precipitation, however, the trend is still uncertainty. Recently, researchers on the climatic change hold two completely different viewpoints on the trend of precipitation in this area. Part of the researchers hold that a warming and drying trend will occur in near future, which is concluded from some indirect evidences such as glacier retreat, lake desiccation and desert enlargement in this area. Others think that there is a warming and wetting trend resulted from decadal comparison of the climatic data in past decades. Thus, it can be seen from above discussion that there is a distinct divergence of views on the precipitation trend in this area. The intention of this paper is further to detect possible trend of annual total and seasonal precipitation records of northern Xinjiang using a non-parametric test. The precipitation series were the records that were observed at thirteen meteorological stations scattered in northern Xinjiang. The Mann-Kendall test was applied to annual and monthly series ranging from 1961 to 1997. The results show that there are four among twelve stations showed a significant upward trend for the annual series. The remaining eight stations showed no significant trend. These results indicate generally that there is a little upward trend in the annual total precipitation series of the northern Xinjiang during the period 1961 ?1997. Two. stations with upward annual trend were specially chosen for monthly trend detecting in order to find out which months have contributed much to the annual trend. The result showed that there are obviously upward trend in the precipitation series of February and December for both Urumqi and Jinghe, which demonstrates that increasing of winter precipitation or snow fall has contributed much to the upward trend in annual precipitation series of the two stations. In order to take into account seasonably, seasonal series also were detected for trend. No trend are found in the spring (represented by April) and autumn (represented by October) series. Two among thirteen showed upward trend in the winter (January) series, which indicates a slight increasing of precipitation in the northern Xinjiang during period 1961 - 1997. In the summer (July) series, one station showed a downward trend, three stations showed an upward trend and the remaining nine stations showed no significant trend. These results demonstrate a small amount increasing of precipitation and a different trend of precipitation variation in the northern Xinjiang during period 1961 - 1997.