Sources of moisture for rainfall in West Africa
Sources of moisture for rainfall in West Africa
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DOI：
10.1029/96wr01940
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发表时间：
1996-10
影响因子：
5.4
通讯作者：
C. Gong;E. Eltahir
中科院分区：
文献类型：
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作者：
C. Gong;E. Eltahir
这项研究的目的是确定西非降雨的水分来源。降水再循环模型的开发和应用到西非地区，以获得定量估计的水分贡献的本地蒸发以及水分贡献的纬向和纬向通量从周围地区。我们通过指定三个将蒸发视为水分来源的子区域来估计整个地区的再循环率：西非，中非和热带大西洋。我们发现，从热带大西洋，西非和中非的蒸发贡献约23%，27%和17%的降雨在西非，分别。来自热带大西洋的水汽通量几乎与西非的降雨同步。然而，我们发现，来自非洲中部的水分供应强烈调节和限制与季风环流的西风气流。因此，大尺度季风环流不仅是西非降雨的主要强迫，而且这种环流的动力学对湿气的来源有重要的控制作用。
The objective of this study is to identify the sources of moisture for rainfall in west Africa. A model of precipitation recycling is developed and applied to the region of west Africa to obtain quantitative estimates of the moisture contributed by local evaporation as well as the moisture contributed by the zonal and meridional fluxes from the surrounding regions. We estimated the recycling ratio for the entire region by specifying three subregions where evaporation is treated as the source of moisture: west Africa, central Africa, and the tropical Atlantic Ocean. We find that evaporation from the tropical Atlantic Ocean, west Africa, and central Africa contribute about 23, 27, and 17% of rainfall in west Africa, respectively. Moisture fluxes from the tropical Atlantic are almost in phase with rainfall in west Africa. However, we find that moisture supply from central Africa is strongly regulated and limited by the westerly flow associated with the monsoon circulation. Hence the large-scale monsoon circulation is not only the main forcing of rainfall over west Africa, but the dynamics of this circulation exert significant control on where the moisture comes from.