IMPACT OF VARIATIONS IN SNOWPACK ONSET AND DISAPPEARANCE DATES ON SURFACE ENERGY BALANCE IN THE ALASKAN ARCTIC

The onset date of the seasonal snow cover in the Alaskan Arctic varies from late September to early October, while the disappearance date of seasonal snow cover ranges from late May through middle June. Variations in snowpack onset and disappearance dates can strongly affect energy exchange between the atmosphere and the surface due to changes in surface conditions. In this study, a surface energy balance approach based one-dimensional heat transfer model with phase change, which is validated against the meteorological data and ground temperatures collected at Barrow, Alaska, was used to quantify the impact of variations in snowpack onset and disappearance dates on the surface energy balance. The model was driven with observed mean daily air temperature, dew point temperature, snow cover depth, incident solar radiation, wind speed, and atmospheric pressure collected at Barrow, Alaska, from 1995 to 1998. A series of simulation cases was conducted by varying the snowpack onset date by 10 days in autumn and the disappearance date by 10 days in spring. The preliminary results indicate that the surface (snow surface when seasonal snow cover was present and ground surface when seasonal snow cover was absent) temperature, net solar radiation, net longwave radiation, sensible heat, latent heat, and conductive heat fluxes all are sensitive to variations in snowpack onset and disappearance dates.