ABSTRACT: In this article, we propose a novel approach for assessing the effects of sea surface temperature (SST) variations in the eastern Pacific and the Caribbean Sea on the Choco low-level jet (CJ) intensity over the 1900-2015 period that involved defining the interbasin gradient index (IGR) between these 2 oceanic basins. We also studied the effects on rainfall in northwestern South America and Central America in the high CJ season during September-November (SON). Wavelet coherence analysis showed high consistency between CJ and IGR on an interannual scale of 2-8 yr. Precipitation increased over central, western, and northern Colombia and most of Central America during strong CJ (SCJ) and decreased during weak CJ (WCJ) events, which occurred, respectively, in the negative IGR (NIGR) and positive IGR (PIGR) phases. NIGR is associated with anomalous cooling in the tropical Pacific and warming in the equatorial Atlantic; opposite patterns are observed during PIGR. Also, the CJ and the Caribbean low-level jet (CLLJ) showed reversed intensities such that as one strengthened, the other weakened and vice versa. Our results indicate that the low-frequency SST anomalies in the North Atlantic affect the IGR and low-level jet intensities associated with changes in large-scale circulation modulated by the Atlantic multidecadal oscillation (AMO). Indeed, positive precipitation anomalies during the SCJ under NIGR were more accentuated and extensive in the warm AMO (WAMO) than in the cold AMO (CAMO) phase. Conversely, negative precipitation anomalies during WCJ under PIGR were more accentuated and extensive in the CAMO than in the WAMO.

中文翻译：

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1900-2015年东太平洋-加勒比海海温梯度在Choco低空急流中的作用

摘要：在本文中，我们提出了一种新颖的方法来评估1900-2015年期间东太平洋和加勒比海海表温度（SST）变化对Choco低空急流（CJ）强度的影响定义了这两个大洋盆地之间的盆地间梯度指数（IGR）。我们还研究了9月至11月（SON）高CJ季节对南美西北部和中美洲降雨的影响。小波相干分析显示CJ和IGR之间的高度一致性，年际范围为2-8年。在强CJ（SCJ）期间，哥伦比亚中部，西部和北部北部以及中美洲大部分地区的降水增加，而在弱CJ（WCJ）事件中则减少，这分别发生在IGR负（NIGR）和IGR（PIGR）负阶段。NIGR与热带太平洋的异常降温和赤道大西洋的变暖有关；在PIGR期间观察到相反的模式。此外，CJ和加勒比低空急流（CLLJ）的强度反转，使得强度增强，另一种强度减弱，反之亦然。我们的结果表明，北大西洋的低频SST异常会影响IGR和与大西洋多年代际振荡（AMO）调制的大规模环流变化相关的低空急流强度。实际上，与冷AMO（CAMO）相比，热AMO（WAMO）中SCGR期间在NIGR下的正降水异常更加突出和广泛。相反，在PIGR下WCJ期间的负降水异常在CAMO中比在WAMO中更加突出和广泛。