LOW-LEVEL CIRCULATION PATTERNS AND PRECIPITATION IN THE ARGENTINE PAMPAS. ASSOCIATION WITH SOYBEAN YIELD.

BETTOLLI ML, PENALBA, OC; VARGAS, WM.

Georgia

Conferencia; 15th Conference on Applied Climatology; 2005

The study of atmospheric circulation patterns and the analysis of their frequency, distribution and temporal variability result    a useful tool for climate diagnostics. Revisions of the analysis methodologies and applications to synoptic-climatology can be found in Barry and Perry (1973), Yarnal (1993) and more recently in Yarnal et al. (2001). For southern South America, Compagnucci et al. (1998) discussed different methodologies for classification of synoptic situations and Compagnucci and Salles (1997) characterised the main synoptic patterns by means of principal component analysis (PCA) of observed daily sea-level pressure for the period 1972-1983. Solman and Menéndez (2003) classified winter daily fields of 500 hPa geopotential heights for the period 1966-1999 by means of K-means clustering technique and studied their relationship with precipitation and temperature in Argentina. Bischoff and Vargas (2003) studied the 500 and 1000 hPa weather type circulations and their relationship with some extreme climatic conditions using reanalyses developed by the ECWMF for the period 1980- 1988. This kind of synthesis are very important to develop objective forecast methods and meteorological-climatic diagnostics to interact with others systems like agriculture or hydrology.Subsequently, in regions with an important world agricultural production it is necessary to study the climate events and related meteorological conditions that have a strong impact on the economy. Argentine Pampas (central-eastern Argentina) is one of these regions being the third-largest producer region of soybean crop in the world (Podesta et al. 1999). Therefore, this work aims to identify characteristics of the atmospheric circulation at low levels over southern South America in order to relate these types to precipitation amounts and soybean yields in the Pampas region.