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.