Warm and cold events in Argentina and their relationship with South Atlantic and South Pacific Sea surface temperatures

Abstract

[1] A Singular Value Decomposition (SVD) analysis was performed jointly on extreme temperature events in Argentina and sea surface temperature (SST) in the South Atlantic and South Pacific. Sea level pressure (SLP) patterns associated with the first SVD coupled mode were also analyzed. Winter is the season of the year that is best represented by the first mode, accounting for up to 70% of the winter covariance between temperature events and SST. The warm and cold events in Argentina are essentially a consequence of the creation of meridional atmospheric circulations over the continent. Such atmospheric patterns result from displacements and intensity changes of the subtropical anticyclones over the oceans and of the continental low-pressure center in northwestern Argentina. The temperature events in southern Argentina are also closely related to the warming and cooling of the coastal waters in the South Atlantic and South Pacific. The analysis suggests that in summer and winter, high (low) occurrence of warm events and low (high) occurrence of cold events are related to similar oceanic and atmospheric circulation situations. The temperature events in Argentina show higher correlation with the Atlantic than with the Pacific, which reflects the importance of the ''orographic barrier'' of the Andes Mountains in driving the atmospheric circulation. The only exception to this rule concerns the warm events in spring, for which the warming of the equatorial Pacific (the ENSO pattern) appears as the dominant mode. The temporal patterns of the temperature events in Argentina exhibit significant interannual variability in fall, winter, and spring, with periods of 3 to 5 years. The summer patterns suggest a very low-frequency variation with a period longer than 20 years.

Surface air temperature trends in Southern Brazil for 1960–2002

“…According to our results this warming has also been identified in southern Brazil. In northern and central Argentina, Rusticucci et al (2003) found that the Atlantic SST is more correlated than the Pacific SST with extreme temperature events in the region, in all seasons except spring. In order to investigate the possible causes of the spatially coherent continental temperature trends, a comparative analysis is made on the annual and seasonal trends in maximum and minimum temperatures in southern Brazil, with the trends in SST in the tropical and extratropical Pacific and Atlantic Oceans.…”

Temperature extremes in the south of South America in relation to Atlantic Ocean surface temperature and Southern Hemisphere circulation

“…In this last case, months with extremely cold temperatures are more frequent. However, in a later study [ Rusticucci et al , 2003] it is possible to see that, except for spring, the ENSO signal is not the main variability mode of temperature extremes in Argentina, but the Atlantic Ocean. This reflects the importance of the orographic barrier of the Andes Mountains in driving the regional atmospheric circulation.…”

“…and (2) Which extreme is more sensitive to SST variability? Four indices are analyzed in this paper, considering warm and cold nights and days instead of mean conditions of warm and cold cases as Rusticucci et al [2003].…”

The Influence of Recurrent Modes of Climate Variability on the Occurrence of Monthly Temperature Extremes Over South America

“…The importance of non‐SAM dynamics is consistent with findings over Uruguay by Renom et al (). Investigation of additional meteorological variables known or likely to be relevant, such as upper level circulation or SST variability over the South Atlantic and Pacific Oceans (Barrucand et al, ; Rusticucci et al, ), would present a more complete picture of the mechanisms that drive extremes here; however, such an investigation is beyond the scope of this current study.…”