Varying roles of ENSO and SAM on the Antarctic Peninsula climate in austral spring

Recent studies have identified a significant warming trend across West Antarctica and the Antarctic Peninsula, which is likely linked to tropical forcing. Here we investigate temporal variations in El Niño–Southern Oscillation (ENSO)–related tropical forcing and Southern Annular Mode (SAM)–related forcing on the Amundsen‐Bellingshausen Seas Low and the regional climate during austral spring. We find a spatial dependency regarding the impacts each of these climate modes have on the Antarctic Peninsula: relationships with ENSO and Antarctic Peninsula climate are persistent and significant across the western Peninsula, while relationships with the SAM are persistent and significant across the northeastern Peninsula. Other ENSO/SAM–Peninsula temperature correlations appear weak since 1957 as they vary temporally, fluctuating in response to changing correlations between the SAM index and the Southern Oscillation Index in austral spring. Changes in the ENSO‐SAM correlations are due primarily to the 1988 La Niña/SAM negative event, which significantly altered the location of the ENSO teleconnection in the South Pacific Ocean and, therefore, its influence on the regional climate. Whether or not there is decadal variability in the ENSO‐SAM relationship remains unclear; however, it is evident that the influence across the Peninsula varies in both space and time, related to the strength and spatial extent of the response in the Amundsen‐Bellingshausen Seas. This suggests that in order to accurately attribute the warming to ENSO‐related tropical forcing, it is necessary to consider the role of the regional circulation manifested by the phase of each climate mode together.