25 March 2009 in Journal of Geophysical Research: Atmospheres
Thirty‐three snowpack models of varying complexity and purpose were evaluated across a wide range of hydrometeorological and forest canopy conditions at five Northern Hemisphere locations, for up to two winter snow seasons. Modeled estimates of snow water equivalent (SWE) or depth were compared to observations at forest and open sites at each location. Precipitation phase and duration of above‐freezing air temperatures are shown to be major influences on divergence and convergence of modeled estimates of the subcanopy snowpack. When models are considered collectively at all locations, comparisons with observations show that it is harder to model SWE at forested sites than open sites. There is no universal “best” model for all sites or locations, but comparison of the consistency of individual model performances relative to one another at different sites shows that there is less consistency at forest sites than open sites, and even less consistency between forest and open sites in the same year. A good performance by a model at a forest site is therefore unlikely to mean a good model performance by the same model at an open site (and vice versa). Calibration of models at forest sites provides lower errors than uncalibrated models at three out of four locations. However, benefits of calibration do not translate to subsequent years, and benefits gained by models calibrated for forest snow processes are not translated to open conditions.
1 January 2013 in Journal of Glaciology
Climate variables that control the annual cycle of the surface energy and mass balance on Zhadang glacier in the central Tibetan Plateau were examined over a 2 year period using a physically based energy-balance model forced by routine meteorological data. The modelled results agree with measured values of albedo, incoming longwave radiation, surface temperature and surface level of the glacier. For the whole observation period, the radiation component dominated (82%) the total surface energy heat fluxes. This was followed by turbulent sensible (10%) and latent heat (6%) fluxes. Subsurface heat flux represented a very minor proportion (2%) of the total heat flux. The sensitivity of specific mass balance was examined by perturbations of temperature (±1 K), relative humidity (±20%) and precipitation (±20%). The results indicate that the specific mass balance is more sensitive to changes in precipitation than to other variables. The main seasonal variations in the energy balance were in the two radiation components (net shortwave radiation and net longwave radiation) and these controlled whether surface melting occurred. A dramatic difference in summer mass balance between 2010 and 2011 indicates that the glacier surface mass balance was closely related to precipitation seasonality and form (proportion of snowfall and rainfall).
1 May 1990 in Journal of Applied Meteorology and Climatology
A snowmelt model based on a heat balance method has been developed. This model takes into account both the heat balance at the snow surface and that of the entire snow cover and simultaneously predicts the snow surface temperature and freezing depth. Observed or estimated incident radiation data are required for operation of the model. Calculated amounts of snowmelt and snow surface temperatures were in agreement with those observed. Dependency of snowmelt on several parameters including maximum liquid water content, thermal conductivity and albedo of the snow was examined. It was found that as liquid water content or thermal conductivity increases, snowmelt decreases. Albedo is very influential in evaluating snowmelt. Runoff from a basin having an area of 583 km2 was estimated using the present model, and was verified by the inflow data to a dam. Abstract A snowmelt model based on a heat balance method has been developed. This model takes into account both the heat balance at the snow surface and that of the entire snow cover and simultaneously predicts the snow surface temperature and freezing depth. Observed or estimated incident radiation data are required for operation of the model. Calculated amounts of snowmelt and snow surface temperatures were in agreement with those observed. Dependency of snowmelt on several parameters including maximum liquid water content, thermal conductivity and albedo of the snow was examined. It was found that as liquid water content or thermal conductivity increases, snowmelt decreases. Albedo is very influential in evaluating snowmelt. Runoff from a basin having an area of 583 km2 was estimated using the present model, and was verified by the inflow data to a dam.
1 January 2001 in Journal of the Meteorological Society of Japan
27 January 2011 in Journal of Geophysical Research
1 December 2008 in Agricultural and Forest Meteorology