Comparison of methods for quantifying surface sublimation over seasonally snow‐covered terrain

Abstract

Abstract:Snow sublimation can be an important component of the snow-cover mass balance, and there is considerable interest in quantifying the role of this process within the water and energy balance of snow-covered regions. In recent years, robust eddy covariance (EC) instrumentation has been used to quantify snow sublimation over snow-covered surfaces in complex mountainous terrain. However, EC can be challenging for monitoring turbulent fluxes in snow-covered environments because of intensive data, power, and fetch requirements, and alternative methods of estimating snow sublimation are often relied upon. To evaluate the relative merits of methods for quantifying surface sublimation, fluxes calculated by the EC, Bowen ratio-energy balance (BR), bulk aerodynamic flux (BF), and aerodynamic profile (AP) methods and their associated uncertainty were compared at two forested openings in the Colorado Rocky Mountains. Biases between methods are evaluated over a range of environmental conditions, and limitations of each method are discussed. Mean surface sublimation rates from both sites ranged from 0.33 to 0.36 mm day À1 , 0.14 to 0.37 mm day À1 , 0.10 to 0.17 mm day À1 , and 0.03 to 0.10 mm day À1 for the EC, BR, BF and AP methods, respectively. The EC and/or BF methods are concluded to be superior for estimating surface sublimation in snowcovered forested openings. The surface sublimation rates quantified in this study are generally smaller in magnitude compared with previously published studies in this region and help to refine sublimation estimates for forested openings in the Colorado Rocky Mountains.

Observations and simulations of the seasonal evolution of snowpack cold content and its relation to snowmelt and the snowpack energy budget

“…Additionally, simulated LTER subalpine peak cold content values were within the range of those reported in a simulation of a subalpine snowpack (-2.2 to -1.7 MJ m -2 ) at 10 the nearby Fraser Experimental Forest during NASA's Cold Land Processes Experiment (Marks et al, 2008). Direct observations of snow surface sublimation were not available for comparison, but modeled sublimation rates were in line with other values reported in the literature for alpine and subalpine areas in the Colorado Rocky Mountains (Berg, 1986;Hood et al, 1999;Knowles et al, 2012;Molotch et al, 2007;Sexstone et al, 2016). On average, SNOWPACK-simulated sublimation represented 28.8% (383 mm) and 11.4% (53 mm) of snow-season precipitation in the alpine and subalpine, 15 respectively.…”

Snowmelt response to simulated warming across a large elevation gradient, southern Sierra Nevada, California

“…Sublimation estimates of 5 to 9 % in the nominal case to 8 to 14 % in the +6 • C scenario (Table S4) are on the lowerto-middle end of the reported regional values of 2 to 3 % (West and Knoerr, 1959) to 20 % (Marks and Dozier, 1992). The large range highlights challenges and disparities in measuring (e.g., Molotch et al, 2007;Sexstone et al, 2016) and modeling (Etchevers et al, 2004) turbulent exchange, which are further compounded in mountainous terrain due to the challenges of wind-flow simulation (Musselman et al, 2015). The simulated reductions in snowmelt volume due to increased sublimation are very small compared to reductions caused by the warming induced shift from snow to rain.…”

Analysis and Predictability of the Hydrological Response of Mountain Catchments to Heavy Rain on Snow Events: A Case Study in the Spanish Pyrenees

“…Turbulent fluxes with the atmosphere were calculated according to the bulk aerodynamic flux method [41][42][43][44]. This method seems to be one of the most reliable according to a comparative study by Sexstone et al [45]. Heat transfer due to precipitation was estimated according to Brun et al [46].…”