Relationship between Convective Precipitation and Cloud-to-Ground Lightning in the Iberian Peninsula

Abstract

The relationship between cloud-to-ground (CG) lightning and convective precipitation over the Iberian Peninsula during the warm season was analyzed. The database covered the period between 1992 and 1994 and the precipitation data from 68 meteorological observatories were used. Temporal and spatial scales of 1 month and 102 km2 were considered. Values of rain yield (defined as the ratio of convective precipitation to CG flash count over a common area) were centered around a mean value of ?108 kilograms per flash (kg fl?1) but varied as a function of the climate regime, increasing from a mean value of 1.2 ? 108 kg fl?1 for the semiarid region of the Iberian Peninsula to a mean value of 2.1 ? 108 kg fl?1 for the humid region of the Iberian Peninsula. The correlation coefficients between convective precipitation and the CG flash count also varied with the climate regime. The correlation coefficient was higher for the semiarid zone (0.75) than for the humid one (0.65). These variations are physically consistent. Within each climate regime, rain yield (correlation) was lower (higher) in July than in June and August, although this result was probably an effect of convective precipitation, which is inflated by frontal precipitation. To test the stability and correlation associated with these results, a ?predicted? convective precipitation for 1994 was calculated using the rain yields of 1992?93. The seasonal correlation coefficient between predicted and gauge-measured precipitation was 0.71.