The aim of this work is to quantify the influence of the position and intensity of the South Pacific High (SPH) over seasonal rainfall in Argentina. Some indices were defined to measure the position and intensity of the SPH, and they were correlated with seasonal precipitation to study the relationship between them. Results indicate that the intensity of the SPH affects precipitation mainly in northern Argentina during spring and in the southern region in autumn and winter. The latitudinal shift of the SPH has proved to have a relevant impact on precipitation in the northeast in summer and winter, and in some regions of southern and central Argentina during winter and spring. When studying the possibility to foresee precipitation behaviour with a one-month lag, these metrics were not able to predict precipitation effectively in the northwest. On the contrary, the SPH intensity showed significant lagged correlations with rainfall mainly in the northeast, central-east and south during spring and summer while the position of the SPH is mostly significantly correlated with summer and winter precipitation in the northeast and central Argentina. Results suggest that the situation of SPH can provide some rainfall predictability.

The objective of this work is to quantify the influence of the position and intensity of the Atlantic High (AH) on seasonal rainfall in Argentina. Monthly precipitation data in 68 stations from the National Meteorological Service of Argentina, the Secretariat of Water Resource and the Territorial Authority of the Limay, Neuquén, and Negro rivers basins (AIC) were used. Correlation was the methodology used to identify the link between seasonal rainfall and some indices especially defined to detect the position and intensity of the anticyclone. Precipitation composites of the years when the value of these indices was extremely high (greater than their second tercile) and extremely low (lower than their first tercile) were built for every season. They were analysed and compared with humidity anomaly transport composites for the same sets of years in order to study circulation patterns associated with seasonal rainfall anomalies. Results indicate that when the AH is intensified, winter rainfall increases in central Argentina and spring rainfall increases in northern Cuyo region. When the AH is displaced towards the north of its mean position, autumn rainfall is favoured in the northeast and central and south Patagonia, meanwhile winter and spring rainfall decreases in central Argentina. When the AH is displaced towards the east of its mean position, summer rainfall decreases in central Andes. Finally, AH indices were used to detect the influence on rainfall in advance. Correlations between seasonal rainfall and the defined indices that characterize the anticyclone in the previous month suggest that there is some rainfall predictability, especially during spring in almost every region in Argentina.