Area‐average rainfall and lightning activity

The aim of the paper is to discuss the statistical relations between the average rainfall parameters for an ensemble of convective cells and the mean lightning occurrence inside this area. The study is based on a data set gathered in France using C and S band radars and two different lightning detection networks. One of them is used to measure L, the cloud to ground flash number. The other one is used to measure Sa, the total cloud to ground and intracloud flash number. The rainfall parameters are 〈R〉 and F(τ), the mean areal rain rate and the fractional rainfall area above a threshold τ, respectively. The results demonstrate that for a single event (i.e., on the spatiotemporal scale of a rain system), significant correlations (1) between the average rainfall parameters, (2) between L and Sa, and (3) between the lightning and the average rainfall parameters are observed. As expected, the correlation between 〈R〉 and F(τ) (1) is very tight for the individual cases as well as for the cluster of the data. The correlations between L and Sa and between the lightning and the average rainfall parameters (i.e., 2 and 3) can be tight in convectively and electrically very active systems (the correlation coefficient between L and F(τ) reaches 0.96). Yet, the parameters of the relations change from one case to another. So, when considered on a climatological scale (i.e., all the data for a season processed together), the 2 and 3 types of correlation diminish or even vanish. However, it is suggested that for homogeneous climatological conditions associated with very active convective clouds, such as, for example, the conditions observed in some tropical areas, and for a homogeneous regime of convection, a tight relation with stable parameters could be expected.