ABSTRACT: This research links global climate to regional weather by considering Caribbean trade wind strength in the context of the large-scale Walker circulation across the Pacific-Atlantic basins, and localized processes involving air-sea interactions between freshwater flux, the ocean mixed-layer depth, and topographic channeling of airflow north of Colombia. Trade wind driven coastal upwelling in the southern Caribbean is enhanced by the Andes Mountains, and creates a focal point for summer climate variability. This emerges in empirical orthogonal function (EOF) analysis of June-July surface zonal winds in the period 1979-2022. Highest EOF loading occurs at 12° N, 75° W northwest of Colombia. Point-to-field correlations with the EOF time score reflect a Pacific-Atlantic thermal dipole and Walker circulation linked with the El Niño-Southern Oscillation (ENSO). As southern Caribbean trade winds weaken, run-off increases, the upper ocean becomes buoyant, and westward currents slacken. Composite differences show that slow trade-wind conditions in June-July induce a counter-current that spreads warm fresh water northeastward from Colombia. This plume disperses toward the Antilles Islands with sufficient memory to triple the number of tropical cyclones in August-September. A slow trade-wind case study in June 2011 emphasizes key air-sea interactions. Channeling of the large-scale airflow north of the Andes Mountains creates a narrow atmospheric bridge for transmission of ENSO signals.

中文翻译：

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加勒比南部地形引导的海洋-大气耦合和夏季气候变化

摘要：这项研究通过考虑太平洋-大西洋盆地大规模沃克环流背景下的加勒比信风强度，以及涉及淡水通量、海洋混合层之间的海气相互作用的局部过程，将全球气候与区域天气联系起来。哥伦比亚北部气流的深度和地形通道。安第斯山脉增强了加勒比南部信风驱动的沿海上升流，并成为夏季气候变化的焦点。这出现在 1979 年至 2022 年期间 6 月至 7 月表面纬向风的经验正交函数 (EOF) 分析中。最高 EOF 载荷发生在哥伦比亚西北部 12° N、75° W。与 EOF 时间分数的点对场相关性反映了与厄尔尼诺南方涛动 (ENSO) 相关的太平洋-大西洋热偶极子和沃克环流。随着南加勒比海信风减弱，径流增加，上层海洋变得活跃，西向洋流减弱。综合差异表明，6月至7月缓慢的信风条件引发了一股逆流，将温暖的淡水从哥伦比亚向东北扩散。这股羽流向安的列斯群岛扩散，其记忆力足以使 8 月至 9 月的热带气旋数量增加两倍。2011 年 6 月的缓慢信风案例研究强调了关键的海气相互作用。安第斯山脉以北的大规模气流的引导形成了一个狭窄的大气桥，用于传输 ENSO 信号。