Spatial patterns of variability for rain fields at different timescales: an application in southern Italy

Rainfall is characterized by spatial variability, which depends on the timescale used. Experiences in analysing rainfall for different time periods have shown, in fact, that the spatial patterns of variability change depending on the time scale (from hours through days and months to seasonal and annual scales). Geostatistics offers a variety of methods for modelling spatial variability and mapping rain fields considered as realizations of random functions. The aim of this study was to analyse and quantify the spatial structure of rain fields at various timescales for climatological and water resources purposes. The data used in this study are a set of different timescales precipitation series registered in Calabria in the last years. Spatial structures of rain fields were identified over the range of timescales most often used in climatological and water resources studies varying from daily to monthly, to seasonal, to annual timescale. Results showed that spatial structure of rainfall measurements changes through the months and as the timescale increases from days to months and seasons to annual total. Orographic precipitation influences global atmospheric circulation and this could explain the different spatial patterns for short and long ranges of variation.