PBL parameterization schemes sensitivity analysis on WRF modeling of a tornadic event environment in Skala Lakonia in September 2015

Abstract

The aim of the present study is the evaluation of the thermodynamic characteristics of a high impact tornadic event in Skala Lakonia, southern Peloponnese, on September 21, 2015. The study was carried out using the Weather Research and Forecasting (AR-WRF) mesoscale model allowing high spatial resolution for the analysis. For the particular model setup used in this study, different planetary boundary layer (PBL) parameterization schemes were tested. The current study downscales ECMWF reanalysis initial and lateral boundary conditions to 1km spatial resolution to assess the mixing layer convective available potential energy (MLCAPE – MCAPE hereafter), the reflectivity perceived by radar (dBZ), the storm relative helicity (SRH) and the energy helicity index (EHI) for the different PBL schemes. The validation was conducted using in situ and remote sensing observations of the surrounding area. The results illustrate deep convective activity with MCAPE values indicating a strong instability in the region of interest using both local and non-local closure PBL schemes. The study evaluates the affectability of the PBL physical processes with regard to the thermodynamic variables on the model performance. Finally, Mellor Yamada Janjic local (MYJ) closure PBL scheme is the best PBL scheme for studying this tornado since its simulation results display deep convection activity along with the highest validation scores.