Seasonal climatology and dynamical mechanisms of rainfall in the Caribbean
Seasonal climatology and dynamical mechanisms of rainfall in the Caribbean
复制标题
加勒比地区的季节气候学和降雨动力机制
DOI：
10.1007/s00382-019-04616-4
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发表时间：
2019
期刊：
影响因子：
4.6
通讯作者：
M. Ting
中科院分区：
文献类型：
--
作者：
Carlos Martinez;L. Goddard;Y. Kushnir;M. Ting
加勒比是一个复杂的区域，严重依赖降雨周期来满足其经济和社会需求。这使得加勒比特别容易受到水文气象灾害(即干旱和洪水)的影响。以前的研究调查了加勒比地区降雨的季节周期，其月度或更长的分辨率往往掩盖了降雨的季节过渡和区域差异。这导致了对季节性周期的不一致的发现。此外，影响该地区气候降雨循环的机制还没有完全了解。为解决这些问题，本研究进行：(1)利用每日观测降水量数据，对加勒比38个站的年降水周期进行主成分分析；(2)利用ERA中期再分析，对加勒比地区的水分收支进行分析。这项研究发现，加勒比地区降水的季节循环取决于三个主要的水汽辐合促进器：东太平洋ITCZ、大西洋ITCZ和北大西洋副热带高压(NASH)的西侧。大西洋暖池和加勒比低空急流改变了这些主要促进者提供的湿度范围。纳什西侧的扩张和收缩形成了加勒比海西北部、加勒比海中部和西加勒比海东太平洋ITCZ降水年周期的双峰型。这项研究确定大西洋ITCZ是小安的列斯群岛中部和南部降水的主要来源，这是造成其单峰降雨模式的原因。次月瞬变的辐合对加勒比海降雨量的贡献很小。
The Caribbean is a complex region that heavily relies on its rainfall cycle for its economic and societal needs. This makes the Caribbean especially susceptible to hydro-meteorological disasters (i.e. droughts and floods). Previous studies have investigated the seasonal cycle of rainfall in the Caribbean with monthly or longer resolutions that often mask the seasonal transitions and regional differences of rainfall. This has resulted in inconsistent findings on the seasonal cycle. In addition, the mechanisms that shape the climatological rainfall cycle in the region are not fully understood. To address these problems, this study conducts: (i) a principal component analysis of the annual cycle of precipitation across 38 Caribbean stations using daily observed precipitation data; and, (ii) a moisture budget analysis for the Caribbean, using the ERA-Interim Reanalysis. This study finds that the seasonal cycle of rainfall in the Caribbean hinges on three main facilitators of moisture convergence: the Eastern Pacific ITCZ, the Atlantic ITCZ, and the western flank of the North Atlantic Subtropical High (NASH). The Atlantic Warm Pool and Caribbean Low-Level Jet modify the extent of moisture provided by these main facilitators. The expansion and contraction of the western flank of NASH generate the bimodal pattern of the precipitation annual cycle in the northwestern Caribbean, central Caribbean, and with the Eastern Pacific ITCZ the western Caribbean. This study identifies the Atlantic ITCZ as the major source of precipitation for the central and southern Lesser Antilles, which is responsible for their unimodal rainfall pattern. Convergence by sub-monthly transients contributes little to Caribbean rainfall.