Analysis of the daily minimum temperatures variability in the Casablanca Valley, Chile

The Casablanca Valley (CV) has a complex topography and is located near the Pacific Ocean. These factors generate important climatic differences in relation to other wine producing zones of Central Chile. The air temperature is one of the most important atmospheric variables in viticulture by its influence on the vine development and the quality of the grapes and wines. In this work, the minimum temperature has been studied using a set of meteorological stations to make a comparative climatology between the CV and surrounding viticultural zones, and also with data from an agrometeorological network inside the CV, to make a local comparison applying the Principal Component Analysis. The synoptic configurations were analyzed for the higher and lower minimum temperatures. The comparison with the surrounding zones shows that the CV has differences in the annual cycle of the minimum temperatures (amplitude and extremes values). Its minimum temperature anomalies are less correlated with the more continental stations, and the differences are statistically more marked and are increasing with growing season. The analysis inside de CV shows low differences, with a 93% of the variance explained by the first principal component, but some oceanic influence exists. The analysis shows that the valley has a well differentiated regime of minimum temperatures compared with other wine-producing zones, noticeable in the warm period. Inside the CV there is a low spatial variability, with an important synoptic control, and it is possible to describe some gradient along the ocean proximity.