Simulations of the Holocene Climate in Europe Using Dynamical Downscaling within the iLOVECLIM model (version 1.1)

This study presents the application of dynamical downscaling in Europe using iLOVECLIM (a model of 10 intermediate complexity), increasing its resolution from 5.56° to 0.25° latitude-longitude. A transient simulation using the appropriate climate forcings for the entire Holocene (11.5 – 0 kyr BP) was done for both the standard version of the model and with dynamical downscaling applied. Our results show that, simulations from dynamical downscaling present spatial variability which agrees better with proxy-based reconstruction and other climate models as compared to the standard model. The downscaling scheme simulates much higher (by at least a factor of two) precipitation maxima and provides detailed 15 information in mountainous regions. We focus on examples from the Scandes Mountains, the Alps, the Scottish Highlands and the Mediterranean. The higher spatial resolution of the dynamical downscaling provides a more realistic overview of the topography, gives local climate information such as precipitation and temperature gradient that is important for paleoclimate studies. The results from the downscaling show in some cases similar magnitude of the precipitation changes reconstructed by other proxy studies (for example in the Alps). There is also a good agreement for the overall trend and spatial pattern than the 20 standard version. Our downscaling tool is numerically cheap which can perform kilometric-multi-millennial simulations and suitable for future studies. models are used to study the past, present and future climate change, two types of global climate models are primarily used, the so-called General Circulation Models (GCMs) and Earth System Model of Intermediate Complexity (EMICs). GCMs and EMICs simulate the climate of the Earth by applying mathematical equations to describe the atmospheric, oceanic and land interactions or feedbacks. These climate models are evaluated with past climate data to ensure that their 30 sensitivity to climate change is realistic, and thus improve their ability to project future climate change. GCMs and EMICs Europe and warming over northern and central Europe. However, our model simulates similar magnitude of warming over northern Scandinavia, which is more in agreement with Mauri et al. (2015). Overall, it can be observed that in many regions for all time slices, the native grid (T21/11.5_Standard) is still seen on the 11.5K_Down model results. This is because the main impact of the dynamical downscaling is to compute physically the climate variables which are connected to temperature in accordance to the sub grid topography for a given course-grid information. were wetter with a precipitation anomaly ranging from 100 mm/yr to 400 mm/yr. and showing more spatial details. This is generally true for 11.5K_Standard but the spatial details do not provide much 295 information compared to the 11.5K_Down grid. North-west Europe has a precipitation anomaly of about 50 mm/yr to 300 mm/yr at 9 kyr BP. In contrast, the dry zone in central Europe is characterized by a precipitation anomaly of up to -50 mm/yr at 9 kyr BP. The impact of dynamical downscaling is seen in the results, as the downscaling reproduces some local topographical features in these regions. The results in the 11.5K_Down suggests that northern Italy was about 50 mm/yr drier relative to the pre-industrial. However, compared to the 11.5K_Standard, northern Italy was relatively up to 50 mm/yr wetter 300 than the pre-industrial. Other regions such as north-east Europe (especially western Russia) was generally dry (about -50 mm/yr) throughout the Holocene for the 11.5K_Down grid at 9 and 6 kyr BP but was relatively wet (up to 50 mm/yr) for 11.5K_Standard. The Iberian Peninsula in the 11.5K_Down grid was between 50 mm/yr and 100 mm/yr wetter than preindustrial at 9 Kyr BP, but up to -50 mm/yr drier than pre-industrial for the simulated 11.5K_Standard.