161 / 2024-09-10 13:18:30

Synchronous Decadal Climate Variability in the Tropical Central Pacific and Tropical South Atlantic

Central Pacific ENSO,Tropical South Atlantic,Decadal variability

Session 65 - Oceanic-atmospheric processes over the Indian and western Pacific Oceans

Pantropical climate interactions across ocean basins operate on a wide range of timescales and can improve the accuracy of climate predictions. Here, we show in observations that Central Pacific (CP) El Niño-like sea surface temperature (SST) anomalies have coevolved with tropical South Atlantic SST anomalies on a quasi-decadal (~10 years) timescale over the past seven decades. During the austral autumn-winter season, decadal warm SSTs in the tropical CP effectively induce tropical South Atlantic SST cooling, mainly through an extratropical atmospheric wave teleconnection in the Southern Hemisphere. This strengthens the South Atlantic subtropical low-level anticyclone and its northern flank easterlies, causing a local ocean-atmosphere positive feedback and enhancing the inter-basin linkage. Concurrently, tropical atmospheric warm Kelvin waves are mostly confined to the Pacific, exerting minor opposing influence on Atlantic SSTs. Partially coupled pacemaker simulations corroborate these findings, indicating that tropical Central Pacific SSTs play a primary pacing role, while Atlantic feedback is of secondary importance throughout the study period. Our results suggest that the tropical CP could be an important source of decadal predictability for tropical South Atlantic SST and the surrounding climate.