Validation of ENVI-met microscale model with in-situ measurements in warm thermal conditions across Athens area

Validation is critical for quantifying accuracy, errors and limitations of models’ results. This study examines the ability of ENVI-met model to simulate thermal conditions in high spatial resolution. Field measurements from 11 central sites (squares and parks) across the greater area of Athens, Greece, incorporating 15 days of campaigns in July and August were used. Air temperature, relative humidity, wind speed, grey globe temperature and total solar radiation were monitored at 1.1 m above the ground using a mobile meteorological station. In addition, Mean Radiant Temperature, Physiologically Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) were calculated incorporating in-situ measurements. The full force method for ENVI-met initial conditions was applied, using hourly data from the nearest meteorological stations. Validation metrics including Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and the index of agreement (d) were used to measure the model accuracy. The results showed that air temperature is simulated with adequate accuracy (MAE = 1.6 ⁰C and d = 0.8) while PET and UTCI also present a high percentage of agreement (MAE = 5.3 ⁰C and 3.3 ⁰C; d = 0.7 and 0.8, respectively). Overall, the study provides further confidence that the ENVI-met can be utilized as a reliable model for further research analysis.