Tendencia de las frecuencias de las olas de frío en la Meseta Central española, entre 1961 y 2010

Abstract

From the series of daily data of anomalies of maximum temperature (ATMAD) and minimum temperature (ATMID), the behavior of cold waves detected in it during the period 1961-2010 is analyzed. Extremely cold days are established based on the thresholds values for ATMAD and ATMID determined by the P10 percentile of the work series. Defines a cold wave as a succession of two or more consecutive days in which the ATMAD and ATMID are below, at the same time, to the established thresholds. The waves of cold in the interval of study are identified and their monthly and annual frequencies are determined. The results indicate that cold waves occur in every month of the year in number between 8 and 16 waves. The months in which fewer cold waves are detected are April (9), July (8) and August (9). The years with most cold waves are 1969, 1971 and 1977 with 7 cases, the rest of the years the annual prevalence is between 1 and 6. Analysis of trend of the series of annual frequencies indicates that there is a decreasing trend of cold waves at a 99% confidence level. If a linear model is considered, in the Spanish Central Plateau has been, from 1961 to 2010, a decrease of cold waves on the order of 0.54 waves every 10 years.