Radar Precipitation Maps as Lightning Indicators

Abstract

Radar maps of precipitation at a height of 6 km have been studied for the thunderstorms of one July day. Regions on these maps within which the intensity level exceeds 30 dBz (corresponding to a rainfall rate of 2.8 mm h-1) represent thunderstorms, some single-celled and some multi-celled. These were found to be the sources of lightning observed (as "sferics") by a radio direction finder, frequency 100 +/- 50 kHz, located at the radar. The sferics rates of the storms were related closely to other storm parameters by: L=2.7 A^(1.64) r^(-1.62), where L is the number of sferics observed per minute, r is the distance of the storm (km), and A the area (km^2) of the storm region as specified above. This study supports the findings of Larsen and Stansbury for an earlier day and adds the algebraic relation.