Analysis of convective precipitation in the western Mediterranean Sea through the use of cloud-to-ground lightning

The monthly convective precipitation (CP) and convective precipitation rate (CPR) over the western Mediterranean Sea are estimated using cloud-to-ground lightning flashes for the June to October period using data of 3 years (1992–1994). Rain yield was computed using the precipitation data from seven observing stations (all equipped with rain gauges) located on the Mediterranean coast of the Iberian Peninsula and in the Balearic Islands. The values obtained were 0.93×108 kg/fl for the negative flashes and 20.63×108 kg/fl for the positive flashes. Convective precipitation over sea was estimated from the rain yield using the cloud-to-ground (CG) lightning activity detected by a lightning detection network. Because no measured data on precipitation over sea are available, the estimated convective precipitation was compared with the monthly diagnostic surface convective precipitation data from the NOAA NCEP/NCAR climate data assimilation system. Analysis of the results revealed that convective precipitation over the western Mediterranean Sea is maximum in the months September and October and near the northeastern coast of the Iberian Peninsula (maximum in the order of 240 mm/month). The convective precipitation rate exhibits less time variability than convective precipitation, although its spatial distribution is similar.