Remote effect of tropical south Atlantic sea surface temperature anomalies on April–June accumulated cyclone energy over the western North Pacific

Abstract

Global processes and their teleconnections, such as the El Niño-Southern Oscillation (ENSO), have been shown to be a large driver of interannual changes in accumulated cyclone energy (ACE) of western North Pacific (WNP) tropical cyclones (TCs), with higher ACE during El Niño and lower ACE during La Niña. However, it remains uncertain whether interannual changes in WNP TC ACE are modulated by sea surface temperature anomalies (SSTAs) in other oceans. This study finds a significant negative correlation between WNP TC ACE during the early season (April–June) and simultaneous SSTAs over the tropical south Atlantic (TSA) in 1970–2021. On average, in warm TSA years, basinwide April–June ACE is significantly lower, with significant ACE decreases mainly occurring over the region spanning 5°–30°N, 115°–150°E. This is a result of reduced TC frequency, intensity and duration, due to a remote modulation of WNP environmental conditions by TSA SSTAs. In warm TSA years, there are significant decreases in 700–500-hPa relative humidity, 850-hPa relative vorticity and 200-hPa divergence and significant increases in 850–200-hPa vertical wind shear over the portion of the WNP with significant ACE reductions. These environmental changes can be linked to an anomalous Walker circulation induced by TSA SSTAs.

Keywords

• tropical cyclone
• accumulated cyclone energy
• western North Pacific