Simulating the Urban Heat Island during heat wave events using WRF urban parameterizations: a case study for Bucharest (Romania)

This study aims to investigate the intensity of Urban Heat Island (UHI) occurring in Bucharest (Romania) during extreme heat events utilizing validated numerical climate modeling procedures. The research is focused on two heatwave episodes in July and August 2023, comparing the high-resolution model output with measurements from the meteorologic stations in Bucharest and satellite-derived land surface temperature (LST) data from Copernicus Sentinel-3 SLSTR and Aqua and Terra MODIS. The study revealed an underestimation of the simulated Surface Urban Heat Island Intensity (SUHII), but confirmed that the UHI is more intense at night. The choice of urban parametrization and Land Use (LU) data created large differences between the modelled SUHII. WRF numerical model implemented with BEP+BEM urban parametrization with LCZ-derived LU fields can produce the most accurate surface temperature simulations out of all the experiments, while BEP with LCZ provided the most precise air temperature forecasts due to lower underestimation of the cooling observed during nighttime. The results highlight detailed urban morphology combined with state-of-the-art urban parameterizations that can accurately simulate the UHI intensity (UHII) and footprint. This paper is the first to combine the WRF model with LCZ data and advanced urban parameterizations for Bucharest.