Relationship between convective precipitation and cloud-to-ground lightning in the Iberian Peninsula

The relationship between cloud-to-ground (CG) lightning and convective prec ipitation over the Iberian Peninsula during the warm season was analyzed. T he database covered the period between 1992 and 1994 and the precipitation data from 68 meteorological observatories were used. Temporal and spatial s cales of 1 month and 10(2) km(2) were considered. Values of rain yield (def ined as the ratio of convective precipitation to CG flash count over a comm on area) were centered around a mean value of similar to 10(8) kilograms pe r flash (kg fl(-1)) but varied as a function of the climate regime, increas ing from a mean value of 1.2 x 10(8) kg fl(-1) for the semiarid region of t he Iberian Peninsula to a mean value of 2.1 x 10(8) kg fl(-1) for the humid region of the Iberian Peninsula. The correlation coefficients between conv ective precipitation and the CG flash count also varied with the climate re gime. The correlation coefficient was higher for the semiarid zone (0.75) t han for the humid one (0.65). These variations are physically consistent. W ithin each climate regime, rain yield (correlation) was lower (higher) in J uly than in June and August, although this result was probably an effect of convective precipitation, which is inflated by frontal precipitation. To t est the stability and correlation associated with these results, a "predict ed'' convective precipitation for 1994 was calculated using the rain yields of 1992-93. The seasonal correlation coefficient between predicted and gau ge-measured precipitation was 0.71.