Ability and Sensitivity of WRF configurations in climate mode to represent urban heat waves' characteristics observed over Paris area during summers 2022 and 2023

The summer of 2022 has experienced several heat waves that were observed over Paris area by a unique network of instruments set up as part of several measurement campaigns gathered under the PANAME 2022 label. In particular, Advanced remote sensing instruments were deployed in a network of unprecedented detail to gather novel profile observations of temperature, wind and aerosol, allowing to characterize the vertical, spatial and temporal variabilities of the atmospheric boundary layer.

The first analyses of these observations were able to highlight the complexity of the processes involved to explain the spatial and temporal variability of temperatures measured during the heat waves of June and July. In particular, marked differences between urban and rural areas are noted, and a high variability in boundary layer heights exists over the period. Wind Doppler lidar and microwave radiometers show the establishment of nocturnal low level jets on some nights and the entrainment of warm tropospheric air in the boundary layer at the end of the period in July when the warmest temperatures were measured. The summer 2022 campaign has also been complemented by a summer 2023's one.

 

The aim of this study is to take advantages of this observational network to better assess the ability of the WRF model torepresentthespatialandtemporalvariabilitiesof urban heatwavesattheresolution of 3km, which is the horizontal resolution used to perform convective-permitting climate simulations. An assessment of the capability of these simulations to study the interactions between climate and urban areas is needed to ensure that vulnerability of cities to climate change and the implementation of specific adaptation policies to make cities more resilient to extreme events can be evaluated with this tool. A set of simulations(3km) was carried out with different configurations and physical parameterizations to test the sensitivity of the WRF model. In particular the role of a better description of cities using WUDAPT dataset and the activation or not of an urban scheme - which makes it possible to better take into account the urban effects related to the density of buildings, their heat capacity, their roughness etc...- will be analyzed.