Development of saltation layer of drifting snow

Abstract

ABSTRACT. The saltation length of aeolian snow particles and a new parameter, the ejection factor, which expresses the degree of erosion due to drifting snow, were obtained as functions of friction velocity by means of wind-tunnel experiments for semi-hard snow cover. The saturated-snowdrift transport rate was also obtained experimentally as a function of friction velocity. Based on these characteristics and the parameter, the development of the saltation layer of drifting snow along the fetch was simulated under various conditions such as snow hardness, wind speed and snowfall intensity. The main results are as follows. The developing distance denoting the distance required for the saltation layer to attain saturation, X sat , is determined by saltation length, ejection factor and saturatedsnowdrift transport rate, all of which depend on wind speed. It is also affected by the magnitude of snowdrift transport rate at the starting point and by the intensity of snowfall if it exists. The dependence of X sat on wind speed is not simple in the case of semi-hard snow cover: X sat increases with wind speed under weak to moderate wind conditions and then decreases under moderate to strong wind conditions. It is sensitive to snow hardness: it is about one order longer on hard snow cover than on semi-hard snow cover. Snowfall reduces not only the value of X sat but also its dependence on snow hardness.

Wind tunnel observations of weak and strong snow saltation dynamics

“…Our modeled conditional average is therefore defined as where τ is the time increments between two consecutive mass flux realizations with τ = 0.05 s. The saltation timescale T q is defined as follows: where L q is the saltation length scale, parameterized according to Sato et al . [], is the mean streamwise flow velocity in the saltation layer where the mass flux is determined, and u * is the friction velocity, obtained by applying equations –.…”

“…where L q is the saltation length scale, parameterized according to Sato et al [2004], U is the mean streamwise flow velocity in the saltation layer where the mass flux is determined, and u * is the friction velocity, obtained by applying equations (1)- (7). Journal of Geophysical Research: Earth Surface…”

Forecasting Experiments Using the Regional Meteorological Model and the Numerical Snow Cover Model in the Snow Disaster Forecasting System

“…The blowing snow model and the road surface model have been developed by SIRC. The blowing snow model diagnoses visibility at a height of 1.2 m, which represents the height from which a typical vehicle driver views the road, and estimates the depth of the snow drift (Sato et al, 2004b(Sato et al, , 2004c. The road surface model diagnoses the surface temperature and the road surface conditions based on a heat budget method (Nishimura et al, 2004).…”