Land-atmosphere feedback in the WRF FPS-URB-RCC sub-ensemble of STAGE-0 simulations: Sensitivity to the model configuration

The CORDEX flagship pilot study on urban environments and regional climate change (FPS-URB-RCC, Langendijk et al. 2024) has been initiated to bridge the gap in understanding interactions between regional climate and urban areas. An initial experiment (STAGE-0) was coordinated within Phase 2 of FPS-URB-RCC, involving 19 institutions to produce an inter- and intra-model ensemble of long-term simulations at convection permitting scale (~3 km) with sophisticated representations of urban environments. In particular, the Weather Research and Forecasting (WRF) model has contributed a large coordinated ensemble, consisting of 29 STAGE-0 sensitivity simulations over the Paris domain. In this study, we use the complete WRF sub-ensemble to examine the influence of model settings on the representation of the land-atmosphere feedback with a focus on urban areas, and its comparison with observational datasets over Paris. We show the sensitivity of the correlation between land-surface and boundary layer variables to available urban parameterization schemes in WRF, land-cover data (e.g., different datasets, inclusion/exclusion of local climate zones, urban area removal), coupling with the PBL and surface schemes, microphysics options, aerosol inputs, and domain size. This ensemble also enables us to quantify internal variability and distinguish it from true model sensitivity, as 10 identical WRF configurations were run on different machines or with slight variations in initial conditions.

Langendijk, G.S. et al. (2024) “Towards Better Understanding the Urban Environment and Its Interactions with Regional Climate Change - The WCRP CORDEX Flagship Pilot Study URB-RCC.” Urban Climate 58:102165. https://doi.org/10.1016/j.uclim.2024.102165.

This work is a part of projects PROTECT (PID2023-149997OA-I00) funded by MICIU/AEI/10.13039/501100011033 and by ERDF/EU, and European Union’s Horizon Europe research and innovation programme IMPETUS4CHANGE (grant agreement No 101081555). JM and AS acknowledge funding by the Ministry for the Ecological Transition and the Demographic Challenge (MITECO) and the European Commission NextGenerationEU (Regulation EU 2020/2094), through CSIC's Interdisciplinary Thematic Platform Clima (PTI-Clima)