Towards the improvement of the representation of the Paris urban heat island in ERA5 using offline SURFEX-TEB (v8.1) simulations and the METEOSAT land surface temperature product

<p>Urban areas concentrate population, wealth, infrastructures, and emissions thus playing a major role on climate change mitigation and adaptation. Therefore, an urgent need for city future climate projections exists to assist stakeholders, organizations and individuals promoting climate mitigation and adaptation measures. Nevertheless, most of the state-of-the-art global and regional climate models have a simplified representation of (or completely neglect) urban climate processes. In the current work, the city of Paris is used as a case study to reveal the shortcomings of the fifth-generation reanalysis from the European Centre for Medium-Range Weather Forecasts (ERA5) and of simulations employing the widely used bulk bare rock approach to urban climate simulation. Afterwards, based on the hourly resolution output of ERA5 and on the Satellite Application Facility Land Surface Analysis (LSA-SAF) land surface temperature product, we show the added value of employing the SURFEX land-surface model coupled to Town Energy Balance (TEB) urban canopy model in simulating the Parisian Surface Urban Heat Island (SUHI) during daytime and the urban heat island during both daytime and night-time. The results display significant the SURFEX-TEB gains in representing the observed daytime and night-time urban heat island effect. SURFEX-TEB diminishes the annual average bias magnitude in 0.5&#186;C for daytime and 1.5&#186;C for night-time, when compared to ERA5 and to bare rock approach. Also, SURFEX-TEB revealed an overall better performance in reproducing the observed daytime SUHI. Finally, the offline SURFEX-TEB framework applied here reveals its improved adequacy to simulate the city climate, which is crucial to build city climate future projections and efficient mitigation and adaptation strategies.</p><p><em>Acknowledgements</em>. The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 &#8211; Instituto Dom Luiz.</p>