History and analysis of the temperature series of Verona (1769-2006)

The reconstruction and climatological analysis of a long series of air temperature measurements in Verona are presented. After careful search of both published and unpublished data from observations conserved in various archives, a dataset covering the period 1769-2006 was evaluated. A careful assessment about quality and reliability was performed on the basis of historical metadata. In order to obtain a complete series of monthly mean values, various gaps were filled with respect to a reference series. The latter was evaluated as a weighted mean based on correlation coefficients with the homogeneous series of Milano (1763-1998), Padova (1725-1997) and Mantova (1828-2005). By application of the Standard Normal Homogeneity Test discontinuities were detected and corrected by application of shifts, evaluated on the basis of the jumps occurring between the average values of the two sub-series before and after the break. The analysis of the resulting annual mean temperature series shows a remarkable cooling episode in 1816, while warmer years occurred in 1772, 1827 and 1828. Linear trends evaluated on time lags of varying length till present show increasing rates for shorter and more recent periods, spring and winter displaying stronger warming rates than the other seasons.