Characteristics of electric field waveforms produced by negative return strokes in Colombia and their comparison with other regions

Abstract

This paper presents the statistical analysis of several parameters associated with the electric field generated by negative cloud-to-ground (CG) lightning flashes recorded in the Bogota savannah (central province of Colombia), including a comparison with other regions. In this way, this is the first study in Colombia where eleven parameters of the electric field and two more related to the electric field derivative are analyzed in detail. From a measuring campaign carried out during the second semester of 2016, 306 negative cloud-to-ground lightning flashes containing the same number of first return strokes (FRS) and 483 subsequent return strokes (SRS) had been analyzed. These return strokes occurred in the range from 3 to 250 km from the measuring station, in such a way that the waveforms analyzed have static components, radiated components or a combination of both. At first, a total of 64.7% of negative CG flashes were categorized as multiple-stroke flashes, the average multiplicity was 2.6 strokes/flash and the maximum value reported was 13 strokes. For the first and subsequent return strokes analyzed in Colombia, the arithmetic mean (AM) of the initial electric field peak normalized to 100 km (EP_N) were 27.6 V/m and 12.4 V/m, respectively. On the other hand, the average of the peak value of the electric field derivative (dE/dt)P was 5.9 V/m/μs for FRS and 3.6 V/m/μs for SRS. These results are similar to those observed in Florida, Germany, Sweden, Japan, Sri Lanka and Malaysia, where the EP_N and the (dE/dt)P for FRS are larger than those for SRS. Furthermore, as reported in Malaysia and other tropical regions, several electric field parameters in Colombia are affected by the geographical location, the distance with respect to the measuring system and the propagation medium. The above was more evident for some temporal parameters such as zero-to-peak rise time, the 10–90% transition duration, the slow front duration and the fast front duration. After comparing with previous data related to natural and rocket-triggered lightnings measured in different regions (tropical, subtropical and temperate latitudes), additional differences were also observed.