We compare five lightning return stroke current models that exhibit a simple relationship between the current at the return stroke channel‐base and the current along the return stroke channel, namely the Bruce‐Golde (BG) model, the transmission line (TL) model, the Master, Uman, Lin, and Standler (MULS) model, the Traveling Current Source (TCS) model, and the Modified Transmission Line (MTL) model, by assuming a common current wave shape at the channel base and then calculating the channel currents and charges and the resultant electric and magnetic fields. There are basically two characteristics that distinguish the models, namely, (1) the treatment of the return stroke wave front and (2) the spatial and temporal distribution of charge removed from the leader channel. The simpler BG model can be used as an excellent approximation to the TCS model. The latter reduces to the former when the current injected downward by the traveling current source has an infinite speed. The MULS model is equivalent to the MTL model when the MULS uniform current is assumed to be zero. The BG and TCS models produce sharper initial field peaks than do the TL, MTL, and MULS models. The ratio of the peak field derivative to the peak current derivative is near the ratio of the peak field to the peak current for the MULS and MTL models and is equal for the TL model, whereas for the BG and TCS models the ratio of the peak derivatives is about twice the ratio of the peak field to peak current. The TL model is unrealistic for long‐time field calculations due to the fact that no net charge is removed from the channel. The other four models produce overall fields which are reasonable approximations to measured fields from natural lightning even though, for the assumed channel‐base current, the BG and TCS models do not reproduce the observed distant‐field zero crossing and the MTL and MULS models do not reproduce the magnetic “hump” observed after the initial field peak at close range. None of the models can reproduce the fine structure observed in the measured fields.

In this paper we present a performance analysis of the European lightning location system EUCLID for cloud-to ground flashes/strokes in terms of location accuracy (LA), detection efficiency (DE) and peak current estimation. The performance analysis is based on ground truth data from direct lightning current measurements at the Gaisberg Tower (GBT) and data from E-field and video recordings. The E-field and video recordings were collected in three different regions in Europe, namely in Austria, Belgium and France. The analysis shows a significant improvement of the LA of the EUCLID network over the past 7 years. Currently, the median LA is in the range of 100 m in the center of the network and better than 500 m within the majority of the network. The observed DE in Austria and Belgium is similar, yet a slightly lower DE is determined in a particular region in France, due to malfunctioning of a relevant lightning location sensor during the time of observation. The overall accuracy of the lightning location system (LLS) peak current estimation for subsequent strokes is reasonable keeping in mind that the LLS-estimated peak currents are determined from the radiated electromagnetic fields, assuming a constant return stroke speed. The results presented in this paper can be used to estimate the performance of the EUCLID network related to cloud-to-ground flashes/strokes for regions with similar sensor baselines and sensor technology.

We have analyzed parameters of 457 upward-initiated negative lightning flashes to the Gaisberg tower (GBT) in Austria recorded from 2000 to 2007. Lightning to the radio tower of a height of 100 m and located on a mountain 1287 m above sea level occurs almost independent of season, although a pronounced thunderstorm season exists in Austria during the summer months. A total of 30% of the upward-initiated negative flashes exhibited one or more return strokes with an average multiplicity of 4.4 and a geometric mean interstroke interval of 17.3 ms. The remaining 70% of upward-initiated negative flashes showed an initial continuous current (ICC) only, either with (22%) or without (48%) superimposed current pulses of peak currents greater than 2 kA. Median of total transferred charge to ground is about 30% lower in summer (26.8 C) than in other seasons (39.0 C). For the return stroke current pulses, we determined a median peak current of 9.2 kA (sigma_log10 = 0.25) and a median pulse charge of 0.51 C (sigma_log10 = 0.39). For current pulses superimposed on the ICC, we determined a median of 4.2 kA (sigma_log10 = 0.26) with 22 kA peak current measured for the largest ICC pulse.

Cloud-to-ground (CG) lightning data from the European Cooperation for Lightning Detection (EUCLID) network over the period 2006–2014 are explored. Mean CG flash densities vary over the European continent, with the highest density of about 6 km⁻² yr⁻¹ found at the intersection of the borders between Austria, Italy and Slovenia. The majority of lightning activity takes place between May and September, accounting for 85 % of the total observed CG activity. Furthermore, the thunderstorm season reaches its highest activity in July, while the diurnal cycle peaks around 15:00 UTC. A difference between CG flashes over land and sea becomes apparent when looking at the peak current estimates. It is found that flashes with higher peak currents occur in greater proportion over sea than over land.