AREA-AVERAGE RAINFALL AND LIGHTNING ACTIVITY

The aim of the paper is to discuss the statistical relations between t he 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 diffe rent lightning detection networks. One of them is used to measure L, t he cloud to ground flash number. The other one is used to measure S-a, the total cloud to ground and intracloud flash number. The rainfall p arameters are [R] and F(tau), the mean areal rain rate and the fractio nal rainfall-area above a threshold tau, respectively. The results dem onstrate that for a single event (i.e., on the spatiotemporal scale of a rain system), significant correlations (1) between the average rain fall parameters, (2) between L and S-a, and (3) between the lightning and the average rainfall parameters are observed. As expected, the cor relation between (R) and F(tau) (1) is very tight for the individual c ases as well as for the cluster of the data. The correlations between L and S-a and between the lightning and the average rainfall parameter s (i.e., 2 and 3) can be tight in convectively and electrically very a ctive systems (the correlation coefficient between L and F(tau) reache s 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 correlatio n diminish or even vanish. However, it is suggested that for homogeneo us climatological conditions associated with very active convective cl ouds, such as, for example, the conditions observed in some tropical a reas, and for a homogeneous regime of convection, a tight relation wit h stable parameters could be expected.