Snowpack sensitivity to perturbed climate changes in alpine catchements

Authors: RASOULI, KABIR - University Of Saskatchewan; POMEROY, JOHN - University Of Saskatchewan; Marks, Daniel

Submitted to: Hydrological Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2015
Publication Date: 11/10/2015
Citation: Rasouli, K., Pomeroy, J., Marks, D.G. 2015. Snowpack sensitivity to perturbed climate changes in alpine catchements. Hydrological Processes. 29(18):3925-3940.

Interpretive Summary: Snow deposition and melt are simulated using the CRHM over a warm region in Idaho (RCEW), and a cold region in the Yukon. The sensitivity of the seasonal snow cover to an unstable climate is evaluated by modulating actual climate conditions around a range of possible future climate conditions. In the more temperate environment, a warming climate resulted in no change to annual precipitation, but increased the percent rain in annual precipitation total, while decreasing blowing snow, drifting and sublimation. I the colder environment, warming increased precipitation which partly compensated for the loss of snow, reduced drifting and earlier melt. Key findings were that forest clearings were least sensitive to climate warming, leading to the concern that since the location of USDA SNOTEL sites is usually in forest gaps we may question the ability of the SNOTEL network to fully represent all of the dynamics involved in changing basin snow hydrology due to climate change.

Technical Abstract: There is great interest in ascertaining the degree of climate change necessary to induce substantial changes in snow accumulation and ablation processes in mountain headwater catchments. Therefore, the response of mountain snow hydrology to changes in air temperature and precipitation was examined by simulating a perturbed climate in Reynolds Mountain East (RME), a headwater catchment with a cool mountain climate in Idaho, USA. The Cold Regions Hydrological Model was used to calculate snow accumulation, wind redistribution by blowing snow, interception by forest canopies, sublimation and melt for 25 seasons in RME. The uncalibrated simulations of the highly redistributed SWE compared well to measurements. Results showed that with concomitant occurrence of warming (5 oC) and precipitation change (±20%) in RME, the peak seasonal snow accumulation dropped by 84-90%, snowmelt decreased 51-79%, rainfall to total precipitation ratio increased from 30% to 78%, and overwinter blowing snow transport and sublimation losses from intercepted snow, the snow surface and blowing snow decreased dramatically. Warming causes an increase in inter-annual snowcover variability but a decrease in spatial snow accumulation variability. The tipping point for snow regime change in RME is a warming of 1 oC and a precipitation increase of 20%; warmer and drier conditions than this would lead to drastic snow hydrology changes. The results contrast with those from further north along the North American Cordillera in Yukon, Canada, where the impacts of warming of 2 oC and more on alpine snow hydrology can be partly compensated for by concomitant increases in precipitation.