1970—2013年西北干旱区空中水汽含量时空变化与降水量的关系

论文基于1970—2013年西北干旱区高空和地面气象资料,采用多种统计学方法,分析了西北干旱区空中水汽含量的时空变化特征及其与降水量的关系。结果表明：1）1970—2002年,西北干旱区空中水汽含量呈显著的增加趋势,速率为0.835 mm/10 a（P<0.01）,其中以夏季增速最高（1.709 mm/10 a,P<0.01）;而降水效率基本稳定,仅春、冬季节略增。在空间上,1970—2002年水汽含量变化速率大小依次为北疆>南疆>河西走廊,其中冬、春季节以北疆水汽增速最大,夏、秋季节以南疆水汽增速最高。2）2003—2013年,西北干旱区水汽含量呈不显著下降趋势（-2.061 mm/10 a）;而降水效率明显增加,速率为0.136%/10 a,这说明近年来空中水汽转化为降水的效率明显提升。同时,北疆降水效率增加幅度明显高于其他地区。3）西北干旱区各季节的降水效率与降水量均呈显著正相关性,而水汽含量与降水量的相关性则表现出明显的季节性差异：春季>夏季>秋季>冬季。另外,新疆降水变化与水汽含量和降水效率均呈显著正相关性,而河西走廊降水量与降水效率的关系更为密切。

The Temporal and Spatial Variation of Water Vapor Content and Its Relationship with Precipitation in the Arid Region of Northwest China from 1970 to 2013

Based on high altitude and ground meteorological data in the arid region of Northwest China from 1970 to 2013, the temporal and spatial variation characteristics of water vapor content in northwest arid area and its relationship with precipitation were analyzed by a variety of statistical methods. The results showed that: 1) The increasing trend of the water vapor content in the arid region of Northwest China was significant at the rate of 0.835 mm/10 a (P<0.01) during the period of 1970-2002. The growth rate in summer was the highest all year round, which was 1.709 mm/10 a (P<0.01). However, the precipitation efficiency in the arid area of Northwest China was basically stable, which only increased slightly in spring and winter. In space, the areas with the variation rate of water vapor content from fast to slow were North Xinjiang, South Xinjiang and Hexi Corridor. In winter and spring, the growth rate of water vapor content in North Xinjiang was the highest, while in summer and autumn, the growth rate of water vapor content in South Xinjiang was the highest. 2) During 2003-2013, the water vapor content did not significantly decrease, whose rate of decline was -2.061 mm/10 a, while precipitation efficiency increased significantly at the rate of 0.136%/10 a, which showed that the efficiency of water vapor’s transforming into precipitation improved significantly. Meanwhile, the increasing rate of precipitation efficiency in North Xinjiang was obviously higher than those in other areas. 3) The precipitation efficiency and precipitation in each season were significantly correlated in the arid region of Northwest China, while the correlation between water vapor content and precipitation had obvious seasonal difference that the correlation in spring was higher than those in summer and autumn and the correlation in winter was the lowest. In addition, precipitation variation was positively correlated with both water vapor content and precipitation efficiency in Xinjiang, while precipitation in Hexi Corridor was more closely related to precipitation efficiency.