全球水汽再循环率的空间分布及其季节变化特征

本文利用ERA-Interim再分析资料,结合新建的水汽再循环数值模式研究了全球降水再循环率和蒸发再循环率的空间分布及其季节变化特征,并给出了主要水汽源地对中国降水的贡献率,结果表明:全球降水再循环率的空间分布特征明显,各地区降水对外界水汽输送的依赖程度不同;陆地蒸发再循环率与降水再循环率的分布大体一致,但是在海洋上差别很大.全球水汽再循环率的季节变化显著,而且北半球降水再循环率的季节变化整体上强于南半球;全球重要水汽源区各季节蒸发再循环率均很低,绝大部分蒸发量都输送到了其他地区.水汽再循环率除与区域的位置、形状有关外,区域的水平尺度也会对其产生影响,随着水平尺度的增大,水汽再循环率呈曲线上升.中国大陆地区降水再循环率为32.6%,蒸发再循环率为44.9%,西北太平洋、南海、孟加拉湾、阿拉伯海以及澳大利亚西部海域对中国降水的贡献较大.本文基于水汽平衡方程建立的数值模式,具有坚实的数理基础,得到的结果可信度较高.

Spatial distribution and seasonal variation characteristics of global atmospheric moisture recycling

This paper makes use of new definitions of moisture recycling to study the complete process of global moisture feedback. An accounting procedure based on ERA-Interim reanalysis data is used to calculate moisture recycling ratios. Furthermore, the spatial distribution and seasonal variation characteristics of global moisture recycling are analyzed. Results indicate that: a) Precipitation recycling ratio in different regions show distinct patterns. It is indicated that the dependences of precipitation in different regions on moisture transport are different. b) Spatial distribution of precipitation recycling ratio and evaporation recycling ratio are in good agreement over the lands, but show significant difference over the oceans. c) Seasonal variation characteristics of global moisture recycling ratio are significant, which are stronger in the Northern Hemisphere than in the Southern Hemisphere. d) Main oceanic sources are dominant over continental moisture recycling, and most of the evaporation is transported to other regions by advection. e) Regional moisture recycling ratio not only depends on the factors such as time, location, and shapes of the regions, but also the regional horizontal scale. The moisture recycling ratio curve rises as the regional horizontal scale increases. It is computed that, on the average, precipitation recycling ratio and evaporation recycling ratio of Chinese mainland are respectively about 32.6% and 44.9%; the main source of rainfall in China is moisture evaporated over the South China Sea, the Bay of Bengal, the Arabian Sea and the Western Australia Ocean. The atmospheric moisture recycling model in this paper is based on the atmospheric water balance equation, in terms of good mathematical and physical theory, hence the results are credible.
Keywords： atmospheric moisture recycling model moisture recycling ratio seasonal variation source of Chinese mainland precipitation