Brief communication "Modeled rain on snow in CLM3 warms soil under thick snow cover and cools it under thin"

Rain-on-snow has decimated ungulate herds in the North and warmed permafrost significantly in Spitsbergen. As the permafrost temperatures are used as an integrated signal of the climate change, there is an urgent need to characterize the relationship between rain-on-snow and permafrost temperatures. By incorporating reanalysis based (ERA40) climate forcing into the land model (CLM3) and introducing an artificial rain on snow event on all model pixels the areas with thick snow cover (>0.5 m) experienced season average permafrost warming, sites with intermediate snow depths (0.15–0.5 m) experienced cooling, while sites with thin snow cover were more sensitive to other factors.