Warmer-than-usual Sea Surface Temperature over the Western Tropical Atlantic Triggers La Nina Events
Unusual sea surface temperature over the tropical Atlantic can influence the following ENSO--- an irregular periodic variation in winds and sea surface temperatures over the tropical Pacific Ocean, affecting the climate of much of the tropics and subtropics. Previous studies have pointed out that the sea surface temperature anomalies over each of the north tropical Atlantic, the Atlantic Nino region and the Atlantic warm pool is able to regulate the air–sea coupling over the tropical Pacific and trigger ENSO events. However, it is still unclear that in which region over the Atlantic ocean the sea surface temperature anomalies has the predominant impact on ENSO variability.
A study recently published in Climate Dynamics by researchers with the Institute of Atmospheric Physics at the Chinese Academy of Sciences and University of Colorado, identifies that the sea surface temperature anomalies over the western tropical Atlantic exhibits a more permanent connection with the following ENSO variability during the observational record. Different SST datasets recognize that ENSO has stronger correlation with the previous spring sea surface temperature anomalies over the western tropical Atlantic than that with the sea surface temperature anomalies over each of the Atlantic Nino region, the north tropical Atlantic or the Atlantic warm pool.
Further analysis suggests that the modulation of the sea surface temperature anomalies over the western tropical Atlantic to the following ENSO is intensified after the mid-1980s, which exhibits as that the warmer-than-usual sea surface temperature over the western tropical Atlantic induce significant precipitation anomalies in situ, and generate atmospheric teleconnection which affects the anomalous zonal wind over the equatorial Pacific, and in turn triggers La Nina events.
"Both observations and CMIP model historical runs imply that this intensified modulation tends to be attributed to the decadal enhancement in climatological mean SST over the western tropical Atlantic." The first author Dr. CHEN Wei said.
Sayram Lake, located in the northern Tianshan Mountains in Xinjiang, China. As the last place to feel the warm air current of the Atlantic Ocean, the lake is nicknamed the "last tear of the Atlantic". (Image by DONG Junjie)
Chen, W., R. Lu, and H. Ding, 2022: A decadal intensification in the modulation of spring western tropical Atlantic sea surface temperature to the following winter ENSO after the mid-1980s. Climate Dyn., https://doi.org/10.1007/s00382-022-06288-z.
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