Modeling the Effect of Variations in Snowpack-Disappearance Date on Surface-Energy Balance on the Alaskan North Slope

Abstract

Variations in the timing and duration of seasonal snow cover have a significant impact on local and regional atmospheric dynamics, hydrologic and geomorphic processes through the modification of the surface-radiation balance and the ultimate effect on near-surface-air temperature. This study investigated numerically the effect of variations in the date of seasonal snow-cover disappearance on the components of surface-energy balance on the Alaskan North Slope by using a heat-transfer model with phase change. The baseline inputs for the meteorological characteristics included mean daily air temperature, dew-point temperature, snow-cover depth, incident solar radiation, wind speed, and atmospheric pressure observed at Barrow, Alaska, from 1995 to 1998. Three simulation cases were conducted by using the measured snow data and by varying the snowpack-disappearance date by 10 days in 1998. The mean differences of the components of surface-energy balance caused by variations in snowpack disappearance were also quantified on an annual basis from July 1997 through June 1998. Results indicate that varying the snowpack-disappearance date by 10 days in spring can strongly affect the mean annual net solar radiation, sensible heat flux, and latent heat flux and can slightly affect the mean annual net longwave radiation and conductive heat flux.