High resolution coupled climate-runoff simulations of seasonal snowfall over Colorado: A process study of current and warmer climate

Finally, climate sensitivity is explored using a Pseudo Global Warming approach. The results show that proper spatial and temporal depiction of snowfall adequate for water resource and climate change purposes can be achieved with the appropriate choice of model-grid spacing and parameterizations. The Pseudo Global Warming simulations indicate enhanced snowfall on the order of 10-25% over the Colorado Headwaters region, with the enhancement being less in the core Headwaters region due to topographic reduction of precipitation upstream of the region (rain shadow effect).

The main climate change impact is the enhanced melting at the lower elevation bound of the snowpack, and increased snowfall at higher elevations. The changes in peak snow mass are generally near zero due to these two compensating effects, and simulated wintertime total runoff is above current levels. The 1 April Snow Water Equivalent (SWE) is reduced by 25% in the warmer climate, and the date of maximum SWE occurs 2-17 days prior to current climate results, consistent with previous studies.