Rainfall variability at Punta Arenas City, Chile, since beginning of 20th century

Abstract

Extended and continuous instrumental records of precipitation are scarce in South America, even more at high latitudes. These records are useful to validate past climatic reconstructions and calibrate regional climatic models. Few Chilean cities (e.g. Santiago, Concepción, and Valdivia) present long meteorological observations, since mid-19th century and/or the beginning of 20th century. The analysis of these records is also key to assessing recent changes In the climate with respect to previous periods. This Information is especially useful for delineating adaptation policies. This paper studied the Punta Arenas rainfall record seeking for the following aims: i) to evaluate monthly, seasonal, and annual variations of rainfall records over the 1900- 2014 and 1990-2014 interval, ii) to evaluate the recurrence of drought extreme events in annual precipitation, and iii) to analyze the relationship between precipitation and the Southern Annular Mode (SAM). The findings evidenced strong decadal to multi-decadal variability in the annual and seasonal precipitation. A significant decrease of the annual precipitation was observed across the 1900-2014 period, becoming more severe in the 1990-2014 period. In this last period, spring and summer precipitation shows also a significant negative trend, suggesting an extension of summer conditions. In winter season, a significant increase was observed since 1990. Extreme drought events have increased since the 1990 year as well. Significant and negative relationships were observed between SAM activity and annual precipitation in March, and September to December months. Decreasing rainfall pattern in Punta Arenas is closely associated with the SAM variability at inter-annual to inter-decadal time scales.