An intercomparison among four models of blowing snow

Four one-dimensional, time-dependent blowing snow models are intercompared. These include three spectral models, PIEKTUK-T, WINDBLAST, SNOWSTORM, and the bulk version of PIEKTUK-T, PIEKTUK-B. Although the four models are base d on common physical concepts, they have been developed by different resear ch groups. The structure of the models, numerical methods, meteorological f ield treatment and the parameterization schemes may be different. Under an agreed standard condition, the four models generally give similar results f or the thermodynamic effects of blowing snow sublimation on the atmospheric boundary layer, including an increase of relative humidity and a decrease of the ambient temperature due to blowing snow sublimation. Relative humidi ty predicted by SNOWSTORM is lower than the predictions of the other models , which leads to a larger sublimation rate in SNOWSTORM. All four models de monstrate that sublimation rates in a column of blowing snow have a single maximum in time, illustrating self-limitation of the sublimation process of blowing snow. However, estimation of the eddy diffusion coefficient for mo mentum (K-m), and thereby the diffusion coefficients for moisture (K-w) and for heat (K-h), has a significant influence on the process. Sensitivity te sts with PIEKTUK-T show that the sublimation rate can be approximately cons tant with time after an initial phase, if K-m is a linear function with hei ght. In order to match the model results with blowing snow observations, so me parameters in the standard run, such as settling velocity of blowing sno w particles in these models, may need to be changed to more practical value s.