Precipitation estimates from an electromagnetic lightning detector data in radiofrequencies

Cloud-to-ground lightning events were monitored during 1995, by a radiofrequencies electromagnetic detection system located in Belem-PA, Brazil. Simultaneously, the pluviometric precipitation was recorded by a FUESS-type pluviograph, located next to the EM-sensors. The relations between cloud electrification and the growth rate of cloud drops, as well as the rain gush after the occurrence of nearby lightning have been observed for a long time, but so far no satisfactory explanation has been offered for these phenomena. Nevertheless, the evident correlation between the frequency of occurrence of the above mentioned type of lightning and the accumulated precipitation levels observed around Belem, led the authors to try to quantify such a relation. Linear regressions between the number of lightning occurrences and the precipitation measured at monthly and hourly intervals, resulted in close parallel lines. The results presented in this work show that in spite of the theoretical difficulties mentioned, EM lightning detection systems have the practical potential to estimate precipitation, when adjusted for a given area of the Earth.