三江源区大气水汽含量时空特征及其转化变化

Spatial-temporal characteristics and changes of atmospheric water vapor in the Three River Headwaters Region

利用1979—2016年ERA-Interim再分析资料提供的1°×1°水汽通量和大气可降水量(PWV)数据,采用相关性分析、趋势分析法、累积距平及反距离加权(IDW)等方法,研究三江源地区PWV与水汽通量的时空分布特征和降水转化率(PCE)。结果表明:①过去38年来,经、纬向多年平均水汽通量分别为2. 0 kg/(m·s)、10. 3 kg/(m·s),水汽通量纬向增幅高于经向,水汽在纬向汇入为主,经向输出为主;②PWV呈微弱增多趋势,年平均PWV为1 791. 6～2 278. 9 mm,季节平均PWV为122. 2～1 134. 2 mm,不同季节内空间差异明显;③三江源区多年平均PCE为24. 6%,1989年最高,达32. 8%;季节与多年平均PCE空间分布一致,都表现出由东南向西北递减的变化特征,季节分布变化差异大;④该地区空中水资源丰富但自然PCE低,开发潜力大,应用前景广阔。

The spatial-temporal characteristics of precipitable water vapor and water-vapor flux as well as precipitation conversion efficiency in the Three River Headwaters Region were discussed through correlation analysis,trend analysis,accumulative anomaly and inverse distance weight based on relevant ERA-Interim reanalysis data from 1979—2016. Some conclusions could be drawn: ① The annual average water-vapor fluxes along the longitudinal and altitude directions in the past 38 years were 2. 0 kg/ (m·s) and 10. 3 kg/ (m·s),respectively. The altitude growth rate of water-vapor flux was higher than that of the longitudinal one. The altitude change of water vapor was mainly input,whereas the longitudinal change was mainly output. ② The precipitable water vapor increased slightly. The annual and seasonal means were 1 791. 6—2 278. 9 mm and 122. 2—1 134. 2 mm,respectively. The spatial difference in different seasons was significantly large. ③ The annual average precipitation conversion efficiency in the study area was 24. 6% and it reached the peak (32. 8%) in 1989. Constant spatial distribution was observed to seasonal and annual average precipitation conversion efficiencies. Both seasonal and annual average precipitation conversion efficiencies decreased gradually from southeast to northwest. Moreover,a great seasonal difference of precipitation conversion efficiency was recognized. ④ Although there were abundant atmospheric water resources in the study area,the natural precipitation conversion efficiency was low,which indicated the promising potentials for development.