Combined performance of September’s Weddell sea ice extent, Southern Annular Mode, and Atlantic SST anomalies over the South American temperature and precipitation

Abstract

This paper aims to analyze the relationships among tropical (Atlantic Meridional Mode - AMM), subtropical (South Atlantic Subtropical Gradient - SASG), and extratropical (Southern Annular Mode - SAM) teleconnection patterns, the Weddell Sea (WS) sea ice extents, and the climate in South America. Warm anomalies are observed in most of South America for maximum WS ice extent combinations (negative SAM/positive AMM and negative SAM/positive SASG composites), with an opposite signal at tropical South America for minimum WS ice extent combinations (positive SAM/negative AMM and positive SAM/negative SASG). Over Southern Argentina, colder (warmer) temperatures are seen at the negative SAM/positive SASG (positive SAM/negative SASG). Drier (wetter) conditions are found over most South America at maximum (minimum) WS ice extent combinations. Wavetrains from different Pacific and Indian Oceans regions are related to high-level anomalous cyclonic (anticyclonic) circulation over the continent at maximum (minimum) WS ice extent configuration, which explains the climate impacts found. The SASG signal displaces the anomaly circulations eastward from South America, impacting the adjacent Atlantic Ocean region more intensely concerning the other modes. The results discussed here indicated that these patterns (SAM, AMM, SASG, and sea ice extent) have significant links with the South American climate variability.

Key words
Antartic sea ice; variability modes; South America; precipitaion; temperature