Modelling and Evaluating the Urban Thermal Environment of Nicosia through the Combined Use of WRF and Satellite Observations

The Eastern Mediterranean and Middle East (EMME) region is an exceptionally thermally vulnerable area, projected to suffer from frequent and severe heat waves in the coming decades. Process-based numerical simulations of the urban climate can provide a cost-effective assessment of urban overheating with greater spatial and temporal resolution than in-situ observations. High-resolution numerical simulations are crucial to assess the impacts of climate change on the urban thermal environment in cities. In this study, the Weather Research and Forecasting (WRF) model was used to dynamically downscale the regional scale (12km) to the local scale (1km) and thus derive high-resolution data for the 2m air temperature and land surface temperature over Nicosia, Cyprus which is located in the EMME region. The simulation was driven by the ERA5 re-analysis, over a three-year period. The WRF model was coupled with the Single Layer Urban Canopy Model (SLUCM) parameterization for a better representation of the urban characteristics of Nicosia. Detailed information on the urban form was inserted into the model through the creation of the Local Climate Zones classification scheme. An evaluation of the simulation results with observation data was performed in terms of annual, monthly, and seasonal values as well as of the capability of the model to identify the urban heat island effect. Following, simulated land surface temperature and spatial patterns were compared with observations from different satellites over Nicosia. Finally, air and surface urban heat island intensity and diurnal dynamics were evaluated using in-situ measurements, reanalysis data, WRF simulations, and remotely sensed thermal observations.