Present-day South American climate
Abstract This paper documents the main features of the climate and climate variability over South America, on the basis of instrumental observations gathered during the 20th Century. It should provide a modern reference framework for paleoclimate research in South America, targeting high-resolution proxies over the past few centuries. Several datasets suitable for present-day climate research are first described, highlighting their advantages as well as their limitations. We then provide a basic physical understanding of the mean annual cycle of the precipitation and atmospheric circulation over the continent and the adjacent oceans. In particular, the diversity of precipitation, temperature and wind patterns is interpreted in terms of the long meridional extent of the continent and the disruption of the large-scale circulation caused by the Andes cordillera, the contrasting oceanic boundary conditions and the landmass distribution. Similarly, the intensity and timing of the interannual and interdecadal climatic fluctuations exhibit considerable geographical dependence, as some regions are more influenced by large-scale phenomena rooted in the tropical oceans while others are more influenced by high-latitude phenomena. The impact of these large-scale phenomena over South America is documented by a regression analysis between selected atmospheric indices and the precipitation and temperature fields. We have included a discussion on the seasonality and long-term stability of such impacts, and complemented our general description by an updated review of the literature on climate variability over specific regions.