Designing and evaluating regional climate simulations for high latitude land use land cover change studies

High latitude regions are undergoing substantial land use and land cover change (LULCC) arising partly from a changing climate (e.g. greening of the Arctic) and climate mitigation policies (e.g. afforestation). Despite these ongoing changes, the impacts of LULCC in high latitudes are poorly understood. Studies to reduce this knowledge deficit primarily deploy regional climate models (RCMs) as observations of key variables for LULCC studies are scarce in high latitude regions. As such it is important to understand the limitations of RCMs and identify best practices for designing regional climate modelling experiments for LULCC studies at high latitudes. In this study, twelve 10-year simulations are performed over the Scandinavian Peninsula; six at convection permitting scales (dx ∼ 3 km) and six at non-convection permitting scales (dx ∼ 15 km). Two of the convection permitting simulations model the present and future climate conditions over the Scandinavian Peninsula. The present-day simulation is comprehensively evaluated for multiple variables (e.g. surface air temperature at 2 m, precipitation) using multiple sources of observations (stations, reanalysis & blended satellite products) where available. Results from the model evaluation points to the need for further model improvement in simulating precipitation and related snow processes as well as the need for observations of surface energy fluxes at high latitudes for evaluation. The remaining eight simulations differ in terms of grid spacing, background climate state (present or future climate), and land cover (conversion of grasslands to evergreen needleleaf or mixed forest). Our study highlights the strengths and limitations of common RCM design considerations, such as simulation length (single year vs. multi-years), background climate state (present vs. future climate) and model resolution (convection permitting vs. non-convection permitting). A key recommendation is that high-latitude modeling studies of LULCC should prioritize computational resources for multi-decadal and ensemble simulations over short, single experiment simulations at convection permitting scales.