Eastern Patagonia Seasonal Precipitation: Influence of Southern Hemisphere Circulation and Links with Subtropical South American Precipitation

Some aspects of the seasonal precipitation over eastern Patagonia, the southernmost area of South America east of the Andes Cordillera, are examined in this paper. Results indicate that the central-north areas, the southern continental region, and the southernmost islands are three independent regions of seasonal precipitation, and that each of them is associated with specific patterns of atmospheric circulation. Precipitation over the central-north region is significantly related to the precipitation over a wide area of southern South America east of the Andes during the four seasons. Enhanced (reduced) precipitation over this area is associated with weakened (intensified) westerly flow in the region. Precipitation over the southern continental area has a close connection with the dipolar pattern of precipitation over subtropical South America during spring, summer, and autumn. The anomalies of atmospheric circulation at low and upper levels associated with the subtropical dipole are also able to modulate the intensity of the westerlies over the south of eastern Patagonia, affecting the regional precipitation. Precipitation over the islands of the southernmost part of eastern Patagonia is connected with subtropical precipitation in summer and winter. The activity of frontal systems associated with migratory perturbations moving to the east along the Southern Hemisphere storm tracks modulates the variability of seasonal precipitation over this region.