Blowing snow
![Blowing snow can occur over snow-covered surface in association with strong winds. Snow particles are lifted into the boundary layer where they are subject to sublimation and horizontal transport over long distances. The snow transport and in-transit sublimation processes affect the moisture and the snow mass budgets. The cooling effect of sublimation also affects the temperature in the boundary layer and thus may play a role in the dynamics of both the boundary layer and the larger scale synoptic flow. This project includes three parts: develop an existent blowing snow model PIEKTUKD; couple the blowing snow model to a 3-d atmospheric model; use the blowing snow-atmospheric model to study the effects of blowing snow on the winter season Northern Hemisphere snow mass budget and anticyclogenesis.
1) Develop 1-d blowing snow model PIEKTUKD
We extended a one-dimensional double-moment blowing snow model (PIEKTUK-D) to a triple-moment version (PIEKTUK-T). The procedure is to formulate predictive equations for three moments of an assumed Gamma particle size distribution for blowing snow. The three moments are the total number concentration, the total mass mixing ratio, and the total radar reflectivity. The results of idealized experiments and real case simulations indicated that PIEKTUK-T predicts well the number concentration, mixing ratio, the shape parameter, and visibility in blowing snow. The model also simulated a power law relationship between the radar reflectivity factor and the particle extinction coefficient consistent with observations in snow storms.
Yang, J. and M.K. Yau (2008) A new triple-moment blowing snow model. Boundary-Layer Meteorol, 126: 137-155. doi: 10.1007/s10546-007-9215-4. [Abstract]
2) Snow mass budget with coupled blowing snow-atmospheric model

The coupled modeling system is applied to study the relative roles of blowing snow sublimation and transport, and surface sublimation on the snow mass budget. Over the three winter months in 2006-2007 in the northern hemisphere, blowing snow sublimation was found to return up to 50 mm Snow Water Equivalent (SWE) back to the atmosphere over the Arctic Ocean. On the other hand, the divergence of blowing snow transport typically accounts for only a few mm SWE in the snow mass budget. When the results are averaged over 10 degree latitudinal bands, the surface sublimation tends to decrease with latitude, while blowing snow sublimation behaves in the opposite direction. Sublimation from surface and blowing snow processes together can return 23% to 52% of winter precipitation back to the atmosphere over the three month winter season.
Yang, J., M.K. Yau, X. Fang and J.W. Pomeroy (2010) A triple-moment blowing snow-atmospheric model and its application in computing the seasonal wintertime snow mass budget. Hydrology and Earth System Sciences, 14: 1063-1079. doi:10.5194/hess-14-1063-2010. [Abstract]
Blowing snow impacts on anticyclogenesis
Yang, J., and M. K. Yau (2011), A case study of blowing snow cooling effects on anticyclogenesis and cyclolysis, J. Geophys. Res., 116, D11113, doi:10.1029/2010JD014624. [Abstract]

Fig: Temperature differences (unit: °C) at 12 m between the CPL and STD runs at t = (a) 12, (b) 24, (c) 36, (d) 48, (e) 60, and (f) 72 h.](Research_%28_I_files/shapeimage_1.png)
