Patterns of Climatic Variation in Argentina and Chile—I Precipitation, 1931–60

Spatial and temporal variability of rainfall in the Nile Basin

“…The trans-polar index (TPI) is defined as the normalized pressure difference between Hobart, Australia and Stanley, Falkland Islands. The TPI (Jones et al, 1999;Pittock, 1980Pittock, , 1984 was obtained from the CRU.…”

Spatio‐temporal rainfall patterns in Southern South America

“…Stations in the eastern foothills of the Cordillera (Bariloche, Esquel, Balmaceda, Lago Argentino and Punta Arenas) show a marked decrease in rainfall due to the rain shadow (Figure 2). Even lower precipitation amounts are recorded for stations close to the Atlantic coast (Trelew, Rivadavia, Gobernador Gregores and Rio Gallegos) where the rainfall originating from the Pacific Ocean is drastically reduced and the air masses coming from the Atlantic Ocean only contribute very sporadic convective rainfall events (Pittock, 1980;Haylock et al, 2006).…”

“…PC1 (21% of the total variance) has the highest positive loading values for stations located in Northwestern Patagonia, on both sides of the Andes between Bariloche and Palena. This area includes nine stations and was previously identified by Pittock (1980), Aceituno (1988), Aceituno et al (1993), Pezoa (2003) and Quintana (2004) as part of the south-central Chile region that shows a clear trend of decreasing precipitation for the last few decades (Figure 4). PC2 accounts for 18% of the variance with the highest loadings from stations located in Central Patagonia close to the Andes between Aysen and Cochrane.…”

“…In addition to the non-normality of the rainfall records themselves, the network of stations in SSAm is sparse and unevenly distributed. An updated analysis of the instrumental precipitation data from Chile and Argentina is necessary because previous comprehensive studies do not include the variations occurred in the last decades (Pittock, 1980;Aceituno, 1988;Compagnucci, 2000). Recent unpublished theses have undertaken this analysis using good-quality and updated data, but only for the Chilean stations (Pezoa, 2003;Quintana, 2004).…”

“…Literature review In his pioneer paper, Pittock (1980) defined several key topics that have been studied over the last 20 years. Using principal component analysis (PCA) he recognized three dominant patterns of year-to-year variability (the first three eigenvectors of the PCA) associated with four indices of general atmospheric circulation: the Southern Oscillation Index (SOI), the Trans Polar Index (TPI), the tropical Atlantic index (S A ) and the Latitude of the subtropical high (L SA ).…”