Thunderstorm activity over South America as inferred from the Sferics and Timing Ranging Network – STARNET

This study presents the evolution of the Sferics and Timing Ranging Network – STARNET since its deployment in July of 2006. STARNET is a long range lightning network that measures sferics continuously through the radio noise emitted by atmospheric discharges that bounces in the ionosphere-earth surface waveguide. This network employs VLF radio antennas developed by Resolution Display Inc that are capable to measure up to 100 sferics per second. During the first years of operation, STARNET was detecting lightning activity mainly in the Amazon basin and northeast of Brazil with location accuracy around 10-20 km and a flash detection efficiency of ~ 50%. After the upgrades in 2007 and 2009, the network has been capable to measure the lightning activity in most part of South America with a location accuracy of 5-10 km and detection efficiency of ~ 70%. For the conference, the location accuracy and detection efficiency evolution will be presented as a function of strokes, flashes and thunder clouds that are evaluated against more defined data (BrasilDat – Brazilian lightning network; and Lightning Imaging Sensor – LIS). Finally, after the detection efficiency correction, STARNET measurements are combined to determine the thunderstorm onset over South America, as well as the regions with the most lightning activity. To validate those results, 10 years of LIS measurements are used as the reference climatology.