Temperature extremes variability in the south of South America in relation to Atlantic SST and the Southern Annular Mode

BARRUCAND MARIANA; RUSTICUCCI MATILDE; VARGAS WALTER

USA

Conferencia; 20th Conference on Climate Variability (88th. American Meteorological Conference; 2008

American Meteorological Society

The objective of this research is to study the main variability modes of the frequency of extreme temperatures in the south of South America (Argentina), their relation to the Atlantic sea surface temperatures and the Southern Annular Mode. Observational data and reanalysis data were used for this propose over the 1964-2003 period. A wavelet analysis showed that the main variability mode found at a seasonal scale was an 8-year wave signal present in spring that remains active until the 90’s. It was noticeable in the analysis of cold nights, Atlantic SSTs, and the Southern Annular Mode (SAM). A cross-wavelet analysis among them reflected this signal as a common variability mode, with the positive phase of the SAM congruent with warmest condition in the coastal zones of the Atlantic Ocean and lower cases of cold nights at the reference meteorological stations analyzed. Although longer series are desirable for low frequency variability analysis, the results agree with previous studies that take into account an 8-year periodicity of the baroclinic waves at the Southern Hemisphere, supporting the relevance of the 8-year signal.