Abstract:

The monthly data of water vapor pressure and precipitation from 1981 to 2015 over Hequ region of the upper reaches of the Yellow River were used to calculate precipitable water (PW) , precipitation conversion efficiency (PCE) by using an empirical formula of total atmospheric PW, and the change trend of precipitable water over there was analyzed. The results show that the PW over Hequ region of the upper reaches of the Yellow River presented a unimodal distribution, while the PCE presented a bimodal distribution. The PW over Hequ region of the upper reaches of the Yellow River increased significantly in recent 35 years, and the average of it was 3 309.5 mm, but precipitation and PCE there showed the opposite trend. According to the mutation test, the PW of spring, summer and annual mutated over Hequ region of the upper reaches of the Yellow River. The temperature was the main climatic factor affecting the variation of PW over Hequ region of the upper Yellow River, followed by relative humidity.

Key words: precipitable water, precipitation conversion efficiency, climate mutation, Hequ region of the upper reaches of the Yellow River

摘要：

利用1981—2015年黄河上游河曲地区5个气象站的水汽压和降水量月资料，运用整层大气可降水量经验公式，计算黄河上游河曲地区大气可降水量和降水转化率，并对大气可降水量的变化特征进行分析。结果表明，黄河上游河曲地区大气可降水量呈单峰形态分布，而降水转化率呈双峰分布。1981—2015年黄河上游河曲地区平均大气可降水量为3 315.5 mm，其间呈显著增加趋势，而降水和降水转化率则呈相反的变化趋势。根据突变检验，黄河上游河曲地区春、夏季和年大气可降水量发生突变，突变时间分别为1985年、1995年和1996年。气温是影响黄河上游河曲地区大气可降水量变化的主要因素，其次为相对湿度。

关键词: 大气可降水量, 降水转化率, 气候突变, 黄河上游河曲地区