Evaluation of the convection-permitting regional climate model CNRM-AROME41t1 over Northwestern Europe

Abstract

Since a decade, convection-permitting regional climate models (CPRCM) have emerged showing promising results, especially in improving the simulation of precipitation extremes. In this article, the CPRCM CNRM-AROME developed at the Centre National de Recherches Météorologiques (CNRM) since a few years is described and evaluated using a 2.5-km 19-year long hindcast simulation over a large northwestern European domain using different observations through an added-value analysis in which a comparison with its driving 12-km RCM CNRM-ALADIN is performed. The evaluation is challenging due to the lack of high-quality observations at both high temporal and spatial resolutions. Thus, a high spatio-temporal observed gridded precipitation dataset was built from the collection of seven national datasets that helped the identification of added value in CNRM-AROME. The evaluation is based on a series of standard climatic features that include long-term means and mean annual cycles of precipitation and near-surface temperature where CNRM-AROME shows little improvements compared to CNRM-ALADIN. Additional indicators such as the summer diurnal cycle and indices of extreme precipitation show, on the contrary, a more realistic behaviour of the CNRM-AROME model. Moreover, the analysis of snow cover shows a clear added-value in the CNRM-AROME simulation, principally due to the improved description of the orography with the CPRCM high resolution. Additional analyses include the evaluation of incoming shortwave radiation, and cloud cover using satellite estimates. Overall, despite some systematic biases, the evaluation indicates that CNRM-AROME is a suitable CPRCM that is superior in many aspects to the RCM CNRM-ALADIN.

Does a convection-permitting regional climate model bring new perspectives on the projection of Mediterranean floods?

“…AROME and ALADIN in retrospective mode (evaluation) show correct annual cycles despite an overestimation of summer temperature both for T min and T max . Results in this area are in line with the recent evaluation of the ALADIN and AROME climate models (Lucas-Picher et al, 2023). The ALADIN RCM is generally colder than AROME, which can be explained by an effect of resolution.…”

“…CNRM-ALADIN has been extensively used in the CORDEX framework over Europe, the Mediterranean, North America and Africa. For more details about the parameterization schemes and configurations of the last version of ALADIN, see Nabat et al (2020) and Lucas-Picher et al (2023).…”

“…Simulations used in this study are produced, as part of the EUCP project, over the NW domain, covering France, the UK, the north of Spain and most of Germany with a 2.5 km mesh. Some papers have already evaluated this model, under a former release (Fumière et al, 2020), a different domain and forcing RCM version (Caillaud et al, 2021;Monteiro et al, 2022), or the same version and domain used in this study (Lucas-Picher et al, 2023). All these evaluations have established the added value of CNRM-AROME in the reproduction of extreme rainfall and HPEs compared to CNRM-ALADIN over the domains.…”

Evaluation of the Convection Permitting Regional Climate Model CNRM-AROME on the complex orographic island of Corsica

“…In the last decade, CP-RCMs have provided insight into precipitation extremes, especially the location and structure of Mediterranean HPEs, for example, in the eastern Mediterranean coast and the Island of Cyprus (Armon et al, 2020), Southeastern France (Fumière et al, 2020;Luu et al, 2022), the Catalonia coast (Meredith et al, 2020), the pan-Europe region (Berthou et al, 2020), the pan-Alpine region (Caillaud et al, 2021;Ban et al, 2021;Pichelli et al, 2021) and the Northwestern Europe region (Lucas-Picher et al, 2023); all these have demonstrated an added value of CP-RCMs in comparison to RCMs.…”

“…Mostly based on numerical weather prediction models, CP-RCMs have a spatial resolution of a few kilometres (< 4 km), in which deep convection is explicitly resolved, instead of being parameterised (Kendon et al, 2012;Prein et al, 2015). Since the early 2010, CP-RCMs have demonstrated an improved representation of complex terrains, as well as the local-scale climate processes such as extreme precipitation (Kendon et al, 2012;Ban et al, 2015;Prein et al, 2015;Kendon et al, 2017;Fumière et al, 2020;Pichelli et al, 2021;Caillaud et al, 2021;Ban et al, 2021;Luu et al, 2022;Lucas-Picher et al, 2023), and orographically induced precipitation (Adinolfi et al, 2021;Monteiro et al, 2022). These processes are particularly relevant for simulating climate conditions over islands.…”