Spatial and temporal variability of precipitation over the Mediterranean Basin based on 32-year satellite Global Precipitation Climatology Project data, part I: Evaluation and climatological patterns

The precipitation regime over the Mediterranean basin is investigated for the period 1979-2010 using monthly mean satellite data from the Global Precipitation Climatology Project (GPCPv2). The results show that a clear contrast exists between the more rainy northern part of the study region (Southern Europe) and the drier southern area (North Africa, Iberian Peninsula) and between the western sides (rainsides) of the Iberian, Italian and Balkan peninsulas and their eastern sides (rainshadows). The mean annual precipitation averaged over the study area is P = 593 ± 203 mm year-1, but it has a strong spatial variability ranging from 20 mm year-1 (North Africa) to 1500 mm year-1 (Alps). A significant seasonal variability exists, with the early winter and late autumn months (November and December) being the wettest with precipitation amounts larger than 60 mm month-1. The GPCPv2 satellite precipitation data are satisfactorily correlated with rain gauge measurements from 433 stations within the study area (correlation coefficient R = 0.78 for all stations on a yearly basis, with values ranging between 0.72 and 0.82, depending on the season) with a slight overestimation. They also compare well with the higher spatial and temporal resolution Tropical Rainfall Measuring Mission (TRMM) data, which supports the validity of the present study.