Sensitivity study on the impact of urban scheme on the simulation of heatwaves in Europe

The main goal of the OP JAK Geohazards project is to study in detail the threats in the Earth's upper spheres, to understand the causes of their occurrence and to quantify the possible impacts on human society. Climate models will be used to evaluate the impact of climate change on risk phenomena, such as heatwaves, with analysis of their causes and assessment of their consequences in selected areas of human activity. In that sense, urban environments are hotspots of anthropogenic emissions, affect the warming rate over cities and induce changes in several relevant meteorological variables such as temperature and horizontal wind speed, which in turn affect air quality and human health. Therefore, it is important to identify how urban parameterizations impact the regional-to-local scale processes in regional climate model simulations. In order to evaluate these impacts in the long term, we need to find the “best” configuration possible for our models by choosing different parameterizations and validating them against high-quality station observations. In this study, we present preliminary results from a series of sensitivity tests focusing on a heatwave event during 2015 and over two cities in Europe, namely Paris and Prague. Simulations were performed using two models (WRF and RegCM5) with nested domains at 27, 9 and 3 km resolution. Urban schemes of different complexity are used in WRF and in RegCM. To validate the ouputs of our simulations, we use the daily gridded observational dataset from EOBS. The results show that relevant meteorological variables, such as temperature and horizontal wind speed, depend on the urban canopy scheme used as well as on the horizontal resolution.