Effect of Regional Hadley Circulation-Subtropical Jet Interaction: The Amplification of Central-Pacific ENSO-Induced Teleconnection Pattern

Abstract

The Pacific North America (PNA), a major teleconnection pattern in North Pacific atmospheric variability, is tightly linked to El Niño-Southern Oscillation (ENSO)-related sea surface temperature (SST) forcing. This study examines the relative effects of eastern Pacific (EP) and central Pacific (CP) ENSO in driving the PNA teleconnection during boreal autumn. Results show that CP SST anomalies are significantly more efficient, with a one-degree CP anomaly inducing more than twice the circulation changes of an equivalent EP anomaly. Two factors contribute to this difference: CP warming triggers stronger atmospheric convection, and the associated regional Hadley circulation (HC) anomaly is broader and shifted westward compared to that induced by EP warming. This enhances interaction with the subtropical jet, strengthening the Rossby wave source. These findings underscore the pivotal role of regional HC in amplifying atmospheric teleconnection patterns, highlighting its importance amid the increasing frequency of CP ENSO events under a changing climate.