Projecting North Eastern Italy temperature and precipitation secular records onto a high-resolution grid

Abstract

Thirty-arc-second resolution monthly temperature and precipitation climatologies for North Eastern Italy are presented and the procedure we adopted in order to superimpose the information of the secular anomaly records to these climatologies is discussed. Temperature climatologies are obtained by means of a step-wise linear regression method which aims at determining the temperature dependence on geographical and morphological variables. In the first regression (temperature versus elevation) the recorded data are considered; the further regressions concern the residuals obtained after taking into account the effect of each variable, in order of importance. Precipitation climatologies are obtained by means of a procedure which consists in considering each cell of a high-resolution grid and in using the 15 closest stations in order to perform a weighted local linear regression of precipitation versus elevation: the weights are given by the distances of the stations from the grid point and by the level of similarity between the stations cells and the considered grid cell in terms of elevation, slope steepness, slope orientation and distance from the sea. Secular records to be superimposed to the climatologies can be obtained for each grid point by means of a distance-weighted average of the anomaly temperature and precipitation records of the neighbouring stations.