Snowmelt sensitivity to radiation in the urban environment

Abstract

Despite having the same snowmelt processes, snowpacks in urban environments experience a range of conditions different from those of rural areas. Melt is intensified at some sites due to greater radiative energy. Shading, however, can reduce radiation and melt at other sites. Changes to the radiation balance and snowpack processes have been investigated. A physical snowpack model was developed and tested against data from an impervious study plot in Sweden. Estimated surface runoff compared favourably with that measured. An urban radiation scheme captured the observed net allwave radiation well. Series of sensitivity analyses were made by perturbing the scheme to represent three urban locations: open ground and the southern (sunny) and north (shaded) sides of a hypothetical building. Cloudiness, albedo, wall temperature and sky view were altered to reproduce common urban conditions. Even without perturbation, the shaded and sunny sides of the building had different radiation fluxes—the south side experienced a daily average net radiation enhancement of 15 W m-2 and the north a decrease of 35 W m-2. This pattern was reflected in melt. Perturbation exaggerated the disparity.