EVAPORATION OF INTERCEPTED SNOW - MEASUREMENT AND MODELING

Snow storage on a coniferous forest canopy was measured using gamma-ra y attenuation and tree weighing systems, along with measurements of th roughfall, using two plastic sheet net rainfall gauges. Meteorological parameters were measured with an automatic weather station. Estimates of evaporation of intercepted snow show an average rate of 0.24 mm h( -1) and a maximum cumulative total of 3.9 mm in 7 h. Comparison with e vaporation determined by a combination method with two different estim ates of aerodynamic resistance (the ''standard'' rain aerodynamic resi stance nu(aL) and a snow aerodynamic resistance nu(aS)-an order of mag nitude larger than nu(aL)) showed that nu(aL) overestimated the evapor ation by a factor of 2.6, whereas nu(aS) gave fair agreement with the measured evaporation. A multilayer model may be needed to take into ac count the variations of latent heat source area. Using the long-term m easurements of the weight of snow on a single tree the total intercept ion evaporation was estimated to be of the order 200 mm year(-1). (C) 1998 Elsevier Science B.V. All rights reserved.