Evaluation of STARNET lightning detection performance in the Amazon region

Abstract

The lightning detection performance of the very low frequency (VLF) long-range Sferics Tracking and Ranging Network (STARNET) was evaluated by comparison with a simultaneous data collection made by the Sistema de Proteção da Amazônia Lightning Detection Network (SIPAM-LDN). The study period was 110 days between August 2008 and March 2009, corresponding to a stable period of the STARNET network when it was operating with five sensors to cover the eastern Amazon region. The selected area of study corresponded to a circle of 130 km diameter within a homogeneous zone of detection efficiency (DE) of the SIPAM network. A method of coinciding flash identification (time window of 1 ms and spatial range of 50 km) was used for these two networks. The coinciding cloud-to-ground (CG) flashes were discriminated by polarity and peak current values from the SIPAM-LDN measurements. The total number of coincident CG flashes represented about 9.7% of the CG SIPAM data set. Moreover, 94 % of the coinciding CG flashes had a time error <300 µs. The spatial error of the coincident CG flashes yielded a mean of around 16 km. The final result shows that the relative detection efficiency (RDE) of the coincident CG flashes decreased with the value of their peak currents. RDE values were below 10% for peak currents lower than 20 kA, between 10% and 30% for peak currents between 20 and 40 kA, and above 30% for peak currents greater than 40 kA.