Local Hydroclimatic Variability and Teleconnectivity Related to Warm and Cold Phases of Atmosphere-Ocean Coupled Circulation

Abstract

Deciphering the El Niño/Southern Oscillation (ENSO) influences on hydroclimatic factors in both tropical and extratropical regions is crucial. This study employed empirical methods to identify areas with consistent hydroclimatic signals in relation to extreme ENSO phases. We examined the climatic linkages between ENSO's warm and cold phases and local temperature patterns across Southeastern US. Spatial coherence values were calculated using monthly temperature composites over a 2-year ENSO cycle, and candidate regions were identified using the first harmonic fit. Temporal consistency rates were determined through aggregate composites and index time series (ITS) to pinpoint core regions. This study identified two core regions: Western Inland Region (WIR) and Easter Coastal Region (ECR), with the WIR showing the more significant response to both warm and cold ENSO forcings. During ENSO warm (cold) years, temperature composites showed below (above) normal levels in these regions from winter to spring. Spatial coherence rates for El Niño (La Niña) in WIR and ECR were 0.97 to 0.98 (0.97 to 0.99), and temporal consistency rates ranged from 0.72 to 0.76 (0.82 to 0.86). Composite-harmonic analysis revealed that temperature anomalies tend to reverse signs between opposite ENSO phases, with positive anomalies in warm years showing more coherence and stronger responses compared to negative anomalies in cold years. The findings indicate that Southeastern US temperature patterns are significantly influenced by ENSO, highlighting a climatic teleconnection between El Niño and La Niña events and local middle latitude temperature.破译厄尔尼诺/南方涛动（ENSO）对热带和温带地区水文气候因素的影响至关重要。本研究采用经验方法来识别与极端 ENSO 阶段相关的具有一致水文气候信号的区域。我们研究了 ENSO 暖期和冷期与美国东南部当地温度模式之间的气候联系。使用 2 年 ENSO 周期内的每月温度合成值计算空间相干值，并使用一次谐波拟合确定候选区域。时间一致性率是通过聚合复合材料和指数时间序列（ITS）来确定的，以查明核心区域。本研究确定了两个核心区域：西部内陆地区（WIR）和复活节沿海地区（ECR），WIR 显示出对暖 ENSO 强迫和冷 ENSO 强迫的更显着响应。在 ENSO 暖（冷）年份，这些地区从冬季到春季的温度合成显示低于（高于）正常水平。 WIR和ECR中厄尔尼诺（拉尼娜）的空间一致性率为0.97至0.98（0.97至0.99），时间一致性率为0.72至0.76（0.82至0.86）。复合谐波分析表明，温度异常往往会在相反的 ENSO 相位之间反转符号，与寒冷年份的负异常相比，温暖年份的正异常表现出更多的一致性和更强的响应。研究结果表明，美国东南部的温度模式受到 ENSO 的显着影响，凸显了厄尔尼诺和拉尼娜事件与当地中纬度温度之间的气候遥相关。