新疆博州地区降水时空分布特征及典型旱涝年

 利用新疆博尔塔拉蒙古自治州地区4个气象站1971—2000年的逐日降水资料,用静态统计论观点分析了博州地区降水时空变化特征,并按适应于西北地区的Z指数旱涝标准统计出了典型的旱涝年。结果表明：①博州地区降水量西多东少,海拔在1 200 m以上的地区为半干旱区,其余绝大多数地区为干旱区或重干旱区,多极端降水事件,自然灾害以旱灾为主洪灾其次,自然生态环境极其脆弱;②年（月）降水量以少于30 a的年（月）平均值为多;③12月至次年2月降水量极小,空间分布呈东多西少型,其他月份则反之;④多雨期出现在夏半年4—9月。其中5—7月大面积干旱与局地洪灾往往并存;⑤山区有两个雨季共5个旬次,平均降水量的月际分布为双峰型,主峰在7月,次峰在5月;其他地区仅1个雨季共两个旬次,平均降水量的月际分布为单峰型,峰值出现在5月;⑥同一气候背景中,博州各个地貌单元的旱涝程度不一,降水空间分布极其复杂。

Spatial-temporal Distribution of Precipitation and Typical Drought or Flood Year over Bole Region in Xinjiang

The day-to-day precipitation data from 1971 to 2000 that recorded at four meteorological stations over Boertala Mongolia Autonomous Prefecture (Bole region for short) were used to analyze the spatial-temporal distribution of precipitation by the method of static statistics, and to determine the typical drought or flood year by the Z-index standard. The results are shown as follows: ①The area above 1200 m is semiarid, most of the others are arid or severe arid where the extreme precipitation events occur more and the natural ecological environment is fragile. ②The yearly or monthly precipitation is often less than their multi-mean value. ③Precipitation is very little from December to next February, during which rainfall in west is more than that in east, vice via in the other months. ④It often rains during April-September, but extensive drought and local flood often coexist from May to July. ⑤There are two rainy seasons(accumulating five ten-day) in the mountains, where the monthly rainfall appears two high peaks in one year, with the main occurs in July and the subordinate in May. There is only one rainy reason (lasting two ten-day) in the other regions, where the monthly rainfall appears one peaks in May. ⑥The drought or flood degrees are different in sub-regions even under same climate background, the spatial distribution of precipitation is extremely complicated.