The Caribbean seasonal rainfall cycle and its characteristics are heavily relied upon by the region’s inhabitants for their socioeconomic needs; the prediction of its variability would be valuable to society. An important way to understand the predictability of the Caribbean rainfall cycle is to study its interannual variability. Previous studies vary as to how and what large-scale climate driver(s) affect the interannual variability of rainfall and its associated dynamical mechanisms in the Caribbean. To address this, this study investigates wet and dry Caribbean early-rainy seasons (ERS; mid-April to mid-June) and late-rainy seasons (LRS; late August to mid-November) by conducting the following: (1) a spatial composite of rainfall from 34 Caribbean rainfall stations using daily data; and, (2) spatial composites of sea-surface temperature, sea-level pressure, and mean flow moisture convergence and transports. The ERS and LRS are impacted in distinctly different ways by two different, and largely independent, dominant large-scale phenomena: the North Atlantic Oscillation (NAO) and the El Niño-Southern Oscillation (ENSO), respectively. Dry ERS years are associated with a persistent dipole of cold and warm SSTs over the Caribbean Sea and Gulf of Mexico, respectively, that were caused by a preceding positive NAO state. This setting involves a wind-evaporation-SST (WES) feedback expressed in enhanced trade winds and consequently, moisture transport divergence over all of the Caribbean, except in portions of the NW Caribbean in May. A contribution from the preceding winter cold ENSO event is also discernible during dry ERS years. Dry LRS years are due to the summertime onset of an El Niño event, developing an inter-basin SLP pattern that fluxes moisture out of the Caribbean, except in portions of the NW Caribbean in November. Both large-scale climate drivers would have the opposite effect during their opposite phases leading to wet years for both seasons. The two rainy seasons are independent because the main drivers of their variability are independent. This has implications for prediction.

该区域居民的社会经济需求严重依赖加勒比地区的季节性降雨周期及其特征。其可变性的预测对社会将是有价值的。了解加勒比降水周期可预测性的一种重要方法是研究其年际变化。先前的研究就如何和何种大规模气候驱动因素影响加勒比地区降雨的年际变化及其相关动力机制而有所不同。为了解决这个问题，本研究通过进行以下活动，调查了加勒比干雨早期和干旱季节（ERS； 4月中旬至6月中旬）和雨季后期（LRS； 8月下旬至11月中旬）：（1）利用每日数据，从34个加勒比雨量站得到的雨量空间组合 （2）海面温度的空间合成，海平面压力以及平均流量水分的汇聚和传输。ERS和LRS受到两种不同且很大程度上独立的占主导地位的大规模现象以明显不同的方式受到影响：分别是北大西洋涛动（NAO）和厄尔尼诺-南方涛动（ENSO）。ERS干年分别与之前的NAO积极状态引起的加勒比海和墨西哥湾持续的冷和暖SST偶极子相关。此设置涉及以增强的贸易风表达的风-蒸发-SST（WES）反馈，因此，整个加勒比海地区的湿气传输差异很大，除了5月在西北加勒比海地区的部分地区。在干旱的ERS年中，也可以看出先前的冬季寒冷ENSO事件的贡献。LRS干旱的年份归因于厄尔尼诺事件的夏季爆发，形成了流域间的SLP模式，该模式将水分排出加勒比海，但11月在西北加勒比海部分地区除外。这两个大规模的气候驱动因素在相反的阶段会产生相反的影响，导致两个季节都处于潮湿的年份。这两个雨季是独立的，因为其变异性的主要驱动因素是独立的。这对预测有影响。