Seasonal variations on the conditions required for the lightning production

Abstract

Given the growing concern on lightning threats outside the main warm-season, the objective of this study is to get further insight on the seasonal variations of the necessary conditions required for the production of lightning. In this regard, the study aims to find a basic indicator of cloud electrification that could be useful as an all-year-round robust predictor to warn about lightning threats. To this end, a large dataset of weather radar data products, total lightning observations and radiosounding isotherm heights have been used. According to previous studies, the radar storm height is tightly correlated with the total lightning flash rate. A fifth order relationship fits from spring to autumn and a third order power law in winter. In spite of the good correlation between the radar storm height and the total lightning flash rate, the vertical development alone may be insufficient as a basic indicator for thunderstorm conditions. Alternatively, two different predictors for the lightning onset have been analysed: 12 dBZ radar reflectivity echoes reaching the -40 °C isotherm height and 35 dBZ reflectivity echoes reaching the -10 °C. Results show that the most suitable all-year-round predictor is the TOP-35 above -10 °C.