Rain on small tropical islands
Rain on small tropical islands
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热带小岛上下雨
DOI：
10.1029/2010jd014695
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发表时间：
2010
影响因子：
--
通讯作者：
S. Yuter
中科院分区：
文献类型：
--
作者：
A. Sobel;C. Burleyson;S. Yuter
[1]根据热带降雨测量使命的降水雷达仪器的观测，高分辨率降雨气候学被用来评估热带小岛屿对气候降雨的影响。面积在100至几千平方公里之间的岛屿被认为是印度-太平洋海洋大陆和加勒比地区的岛屿。将每个岛屿的年平均气候降雨量（1997-2007年）与周围海洋区域的年平均气候降雨量进行比较，差异以百分比表示。除了总降雨量，降雨频率和强度也进行了分析。结果分层成两个12小时半的昼夜周期，以及8个3小时的周期，并通过测量每个岛屿的地形起伏。在这两个区域，较大的岛屿（面积为几百平方公里或更大）和较小的岛屿之间有明显的差别。与周围的海洋相比，在较大的岛屿上，降雨频率和总降雨量都显着增加。对于较小的岛屿的增强是可以忽略不计的小，统计上不显著，或在加勒比雨频率的情况下，负。较大岛屿的总降雨量增加，部分原因是频率更高，部分原因是强度更大。岛屿增强的日周期在频率上是明显的，但强度不明显，除了加勒比小岛屿，匡威亦然。对于较大的岛屿，较高的地形与更大的降雨量增加有关。加勒比海的地形影响比海洋大陆大。地形降水增强表现为降水频率的增加而不是强度的增加，并且在夜间和白天都存在。缺乏一个明确的日周期在地形增强表明，大部分的地形降雨增强是由于机械强迫上坡流，而不是升高的表面加热。
[1] A high-resolution rainfall climatology based on observations from the Tropical Rainfall Measuring Mission's Precipitation Radar (PR) instrument is used to evaluate the influence of small tropical islands on climatological rainfall. Islands with areas between one hundred and several thousand km2 are considered in both the Indo-Pacific Maritime Continent and Caribbean regions. Annual mean climatological (1997–2007) rainfall over each island is compared with that over the surrounding ocean region, and the difference is expressed as a percentage. In addition to total rainfall, rain frequency and intensity are also analyzed. Results are stratified into two 12 h halves of the diurnal cycle as well as eight 3 h periods, and also by a measure of each island's topographic relief. In both regions, there is a clear difference between larger islands (areas of a few hundred km2 or greater) and smaller ones. Both rain frequency and total rainfall are significantly enhanced over larger islands compared to the surrounding ocean. For smaller islands the enhancement is either negligibly small, statistically insignificant, or, in the case of Caribbean rain frequency, negative. The enhancement in total rainfall over larger islands is partly attributable to greater frequency and partly to greater intensity. A diurnal cycle in island enhancement is evident in frequency but not intensity, except over small Caribbean islands where the converse is true. For the larger islands, higher orography is associated with greater rainfall enhancements. The orographic effect is larger (percentagewise) in the Caribbean than in the Maritime Continent. Orographic precipitation enhancement manifests more strongly as increased frequency of precipitation rather than increased intensity and is present at night as well as during the day. The lack of a clear diurnal cycle in orographic enhancement suggests that much of the orographic rainfall enhancement is attributable to mechanically forced upslope flow rather than elevated surface heating.