Land–atmosphere interactions in sub-polar and alpine climates in the CORDEX Flagship Pilot Study Land Use and Climate Across Scales (LUCAS) models – Part 2: The role of changing vegetation

Abstract

Abstract. Land cover in sub-polar and alpine regions of northern and eastern Europe have already begun changing due to natural and anthropogenic changes such as afforestation. This will impact the regional climate and hydrology upon which societies in these regions are highly reliant. This study aims to identify the impacts of afforestation/reforestation (hereafter afforestation) on snow and the snow-albedo effect and highlight potential improvements for future model development. The study uses an ensemble of nine regional climate models for two different idealised experiments covering a 30-year period; one experiment replaces most land cover in Europe with forest, while the other experiment replaces all forested areas with grass. The ensemble consists of nine regional climate models composed of different combinations of five regional atmospheric models and six land surface models. Results show that afforestation reduces the snow-albedo sensitivity index and enhances snowmelt. While the direction of change is robustly modelled, there is still uncertainty in the magnitude of change. The greatest differences between models emerge in the snowmelt season. One regional climate model uses different land surface models which shows consistent changes between the three simulations during the accumulation period but differs in the snowmelt season. Together these results point to the need for further model development in representing both grass–snow and forest–snow interactions during the snowmelt season. Pathways to accomplishing this include (1) a more sophisticated representation of forest structure, (2) kilometre-scale simulations, and (3) more observational studies on vegetation–snow interactions in northern Europe.

Delivering an Improved Framework for the New Generation of CMIP6-Driven EURO-CORDEX Regional Climate Simulations

“…The CORDEX FPS-LUCAS (Land use and climate across scales) is a European initiative that provides a common protocol for implementing land use changes in coordinated RCM experiments (Rechid et al, 2017). Idealized experiments to investigate and inter-compare the overall model agreement in winter temperature response to afforestation in Europe and a large inter-model spread in summer, due to different sensible and latent heat flux partitioning (Davin et al, 2020); the need for a careful selection of tailored metrics to interpret the complex biogeophysical processes occurring when land use changes are implemented in RCMs (Breil et al, 2020); the relevance of soil processes especially in areas and seasons of strong land-atmospheric coupling ; the importance of snow physics and the high uncertainty they impose especially during the ablation period, affecting considerably the regional climate of northern Europe (Daloz et al, 2022.…”

Spatial spin-up of precipitation in limited-area convection-permitting simulations over North America using the CRCM6/GEM5.0 model

“…Dynamical downscaling with regional climate models (RCMs; Giorgi, 2019) using limited-area domains is a more efficient way to run at convection-permitting resolutions since the computational cost is reduced considerably compared to global convection-permitting simulations (Prein et al, 2015;Lucas-Picher et al, 2021). In recent years, several multimodel convection-permitting model (CPM) initiatives have been implemented in the context of the Coordinated Regional Climate Downscaling Experiment (CORDEX) Flagship Pilot Studies (Coppola et al, 2020;Ban et al, 2021;Mooney et al, 2022). Limited-area models must be forced at the lateral boundaries (and sometimes in the interior of the domain) by reanalysis data for hindcast studies or by simulated data generated using global or regional (with a larger domain) climate models (e.g., Earth system models, ESMs) (Laprise et al, 2008).…”

Snow depth in high-resolution regional climate model simulations over southern Germany – suitable for extremes and impact-related research?

“…In global or regional earth-system model setups, snow dynamics are simulated coupled with atmospheric processes and other landsurface processes (Krinner et al, 2018). However, the spatial resolution of global and regional models is often not sufficient to represent complex terrain and the spatial variability of the land-surface (Mooney et al, 2022). Further, the simulated climate and snow dynamics show biases (Daloz et al, 2022).…”