Climate Change Impacts on Atmospheric Circulation and Daily Precipitation in the Argentine Pampas Region

PENALBA, OLGA C; BETTOLLI, MARIA LAURA

Climate Change - Geophysical Foundations and Ecological Effects

Juan Blanco and Houshang Kheradmand (Ed.), InTech

Año: 2011; p. 137 - 156

The region of interest in this study is the Pampas region, which comprises the most productive agricultural lands of Argentina. The most important grains of the country, like soybean, corn, wheat and sunflower are grown in this region. Together with their byproducts, these crops promote the social and productive system of the region, and are one of the principal sources of fiscal incomes. In the campaign of 2008/09, more than 24 million hectares, compared to of the country’s total of 28 million cultivated hectares of these grains, corresponded to the Pampas region (http://www.sagpya.mecon.gov.ar/). This region, located in the center east of Argentina, southeastern South America, have an extension of more than 600.000 km2. Since the grains are cultivated extensively without artificial irrigation, the precipitation is one of the climatic variables of main influence for the production, and is also a condition for the management of the crops. Therefore, the spatial and temporal distributions of the precipitation in the region, and its surplus or deficit, are of extreme importance for the successful harvests. The skill of the GCMs in representing the circulation that conducts or conditions the precipitation events has an important role in the evaluation of future climate projections. However, the capacity of the GCMs in representing the circulation on a synoptic scale has been little explored up to now. The usefulness of the GCMs in local studies is restricted by their poor spatial resolution. Techniques of scale reduction have been developed as bridges between the large scale information generated by the GCMs and the local scale information, with the purpose of performing short- to midrange forecasts and to study the potential impacts of future climate change. In this way, the use of daily results from the GCMs for studies of local climate is subject to their aptitude in representing the atmospheric systems on a regional scale. In this context, the present chapter is structured to fulfill the following objectives: to characterize the rainfall conditions and their probability of occurrence in the Pampas region; to identify daily circulation patterns in southern South America and to associate them with different rainfall conditions in the Pampas region; to evaluate the representation of the daily circulation patterns as simulated by a set of 12 GCMs; and to analyze the projected changes of the same patterns at different time horizons of the 21th century.