Study of lightning occurrence in the southeastern Brazil and its relationship with polarimetric variables observed by meteorological radar

Abstract

The motivation of this research is to contribute to the knowledge about the relationship between the occurrence of lightning and hydrometeors present in storms, through polarimetric observations with meteorological radar and the application of the semi-supervised methodology of Besic et al. (2016) for the classification of hydrometeors. The objective is to develop a linear regression equation that correlates the mass of hydrometeors with the lightning rate, through the lightning provided by the Earth Networks Total Lightning Network, commonly known as ENTLN, for part of the southeastern region of Brazil. For this, the Z-M relationship between the radar reflectivity and the amount of hydrometeor mass present in the radar volume was used to compare it with the lightning density rate. During the period from 2019 to 2022, it was observed that the reported hail precipitation events coincide with the precipitable graupel indicated through the classification of hydrometeors algorithm. In these events, the trend of ice mass over the hours was similar to that of the observed lightning. The results show a significant correlation between these two parameters for different regions with distinct land cover, urbanization and topography, including ocean. Demonstrating that it is possible to develop empirical equations to relate ice mass to lightning density rates. This approach can contribute to lightning assimilation techniques, aiding in nowcasting.