Patterns of Climatic Variation in Argentina and Chile—II. Temperature, 1931–60

A. B. Pittock CSIRO Division of Atmospheric Physics, Mardialloc, 3195, Australia

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Abstract

A 30-year data set of monthly means of the daily mean temperatures at a selected network of 50 stations in Argentina and Chile has been analyzed. Eigenvector analysis reveals that the first three patterns of year-to-year variability account for 42, 14 and 7% of the total variance, respectively. The most dominant pattern shows temperature anomalies of the same sign over practically the whole area, but these are highly seasonal, being correlated negatively with the east-west pressure difference across the tropical Atlantic in fall and winter, and positively in early summer. This seasonal reversal is found to be due to the seasonal reversal in land-sea temperature difference off the central Argentine coast. The second eigenvector of the temperature variations is most strongly correlated with the pressure difference between the Tasmanian and Falkland Islands regions, while the third eigenvector is associated with variations in the latitude of high pressure belt along the coast of Chile.

These results confirm those found for precipitation in Part I (Pittock, 1980) in that a few dominant circulation anomaly mechanisms appear to account for a major part of the climatic variations over Argentina and Chile. Clearly. these circulation mechanisms should be studied further, as should the relationship between Argentinean climate and sea surface temperature fluctuations in the south-west Atlantic.

Abstract

A 30-year data set of monthly means of the daily mean temperatures at a selected network of 50 stations in Argentina and Chile has been analyzed. Eigenvector analysis reveals that the first three patterns of year-to-year variability account for 42, 14 and 7% of the total variance, respectively. The most dominant pattern shows temperature anomalies of the same sign over practically the whole area, but these are highly seasonal, being correlated negatively with the east-west pressure difference across the tropical Atlantic in fall and winter, and positively in early summer. This seasonal reversal is found to be due to the seasonal reversal in land-sea temperature difference off the central Argentine coast. The second eigenvector of the temperature variations is most strongly correlated with the pressure difference between the Tasmanian and Falkland Islands regions, while the third eigenvector is associated with variations in the latitude of high pressure belt along the coast of Chile.

These results confirm those found for precipitation in Part I (Pittock, 1980) in that a few dominant circulation anomaly mechanisms appear to account for a major part of the climatic variations over Argentina and Chile. Clearly. these circulation mechanisms should be studied further, as should the relationship between Argentinean climate and sea surface temperature fluctuations in the south-west Atlantic.

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