engleski

Lightning Potential Index performance in convection-permitting simulations of hail events in Croatia – sensitivity to microphysics and PBL schemes

Mediterranean Basin is struck every year with convective weather events that cause dozens of fatalities and millions euros of damage. Lightning activity is a characteristic phenomenon that often accompanies severe weather, and especially hailstorms. Lightning Potential Index (LPI) is a measure of the potential for charge generation and separation, which results in lightning flashes during convective thunderstorms. Considering the relationship between significant lightning activity and deep convective processes, such as hail, we assessed the ability of LPI to represent the observed lightning activity that accompanied several hail events in Croatia. Selected hail events are simulated using Weather Research and Forecasting (WRF) model at cloud permitting grid spacing (1 km). Using vertical profiles of liquid and ice water content and vertical velocity, LPI is determined directly from the model’s output fields. Thus, LPI maps the area that has the potential for electrical activity based on both model’s dynamical and microphysical fields. Moreover, we formed an ensemble of simulations with combinations of three different planetary boundary layer (PBL) and four different microphysics parameterization schemes for each analyzed hail event. Further, we assessed the sensitivity of LPI to parameterization scheme choice and investigated LPI’s ability to reproduce the temporal and spatial characteristics of the lightning activity observed with LINET network. Our results indicate that LPI is more sensitive to microphysics than PBL parameterization schemes with one of the microphysics schemes systematically underperforming the others. Possible reasons for such discrepancies are addressed as well.

Lightning ; WRF ; Hail

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