An empirical model of snowdrift based on field measurements: Profiles of the snow particle size and mass flux

Abstract

Snowdrift often occurs in cold regions due to the combination of wind and snowfall. The drift formation and movement processes are complex due to the mixture of air, snow and sometimes water as well as the interaction of the temperature, humidity, pressure and flow. To better understand the relevant motion of blowing snow and the vertical snow distribution at an open terrain, the present study creates an empirical model of blowing snow, with the snow particle size and snow flux profile obtained by field measurements in Xinjiang autonomous region in northwest China. Based on the current data, we summarize and analyze the snow particle size probability distribution, the mean equivalent diameter profile and the snow mass flux profile in drifting snow. The results show that the probability distribution of the equivalent diameter of different snow particles (e.g., new snow, deposited snow, and blowing snow) follows the gamma distribution, and these parameters significantly vary for different types of snow particles. The mean equivalent diameter and mass flux of blowing snow considerably decrease with height. The friction velocity is an important factor that affects the profiles of the snow particle size and snow mass flux. The empirical model of the distribution of the particle diameter and mass flux proposed in the present study considering the friction velocity agrees well with field measurements.