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Numerical simulation of drifting snow sublimation in the saltation layer.

Dai X, Huang N - Sci Rep (2014)

Bottom Line: Previous studies of drifting snow sublimation have focused on suspended snow, and few have considered saltating snow, which is the main form of drifting snow.The simulated results show 1) the average sublimation rate of drifting snow particles increases linearly with the friction velocity; 2) the sublimation rate gradient with the friction velocity increases with increases in the environmental temperature and the undersaturation of air; 3) when the friction velocity is less than 0.525 m/s, the snowdrift sublimation of saltating particles is greater than that of suspended particles; and 4) the snowdrift sublimation in the saltation layer is less than that of the suspended particles only when the friction velocity is greater than 0.625 m/s.Therefore, the drifting snow sublimation in the saltation layer constitutes a significant portion of the total snow sublimation.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Mechanics on Disaster and Environment in Western China, Lanzhou University, Lanzhou 730000, China.

ABSTRACT
Snow sublimation is an important hydrological process and one of the main causes of the temporal and spatial variation of snow distribution. Compared with surface sublimation, drifting snow sublimation is more effective due to the greater surface exposure area of snow particles in the air. Previous studies of drifting snow sublimation have focused on suspended snow, and few have considered saltating snow, which is the main form of drifting snow. In this study, a numerical model is established to simulate the process of drifting snow sublimation in the saltation layer. The simulated results show 1) the average sublimation rate of drifting snow particles increases linearly with the friction velocity; 2) the sublimation rate gradient with the friction velocity increases with increases in the environmental temperature and the undersaturation of air; 3) when the friction velocity is less than 0.525 m/s, the snowdrift sublimation of saltating particles is greater than that of suspended particles; and 4) the snowdrift sublimation in the saltation layer is less than that of the suspended particles only when the friction velocity is greater than 0.625 m/s. Therefore, the drifting snow sublimation in the saltation layer constitutes a significant portion of the total snow sublimation.

No MeSH data available.


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A comparison between the sublimation rates of saltating particles and suspended particles of snow.
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f3: A comparison between the sublimation rates of saltating particles and suspended particles of snow.

Mentions: Bintanja25 studied the relationship between the surface and snowdrift sublimation in the katabatic wind region of the Antarctic ice sheet. He assumed that the vertical distribution of the suspended-particle density obeys the standard power-law relation26 and calculated the snowdrift sublimation rate of suspended snow particles. In this study, the motion equations of wind blowing snow are established to obtain the particle velocity and the vertical distribution of particle number density in the saltation layer. Then, the sublimation rate is calculated using the expression of Thorpe and Mason9 under the same values of model variables associated with particles as used by Bintanja25. For comparison purposes, the results of Bintanja are shown with our results in Figure 3. The snowdrift sublimation of Bintanja is obviously less than ours when the friction velocity is less than 0.525 m/s. In other words, the DSS of saltating particles is greater than that of suspended particles, and the difference between them gradually increases as the friction velocity decreases. When the friction velocity is greater than 0.362 m/s but less than 0.525 m/s, the sublimation rate of saltating particles ranges from 36.3 W m−2 to 51.3 W m−2, i.e. 1.1 mm d−1 SWE to 1.6 mm d−1 SWE, indicating that the snowdrift sublimation rate in the saltation layer is so considerable that it should be considered. The snowdrift sublimation rate of saltating particles is less than that of the suspended particles only with a very high friction velocity (great than 0.625 m/s). Therefore, DSS in the saltation layer is of significance and should not be neglected in the prediction of DSS. Figure 3 also shows that the snowdrift sublimation rate in the saltation layer increases linearly with the friction velocity, reaching 75.6 W m−2 at a friction velocity of 0.726 m/s.


Numerical simulation of drifting snow sublimation in the saltation layer.

Dai X, Huang N - Sci Rep (2014)

A comparison between the sublimation rates of saltating particles and suspended particles of snow.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4196100&req=5

f3: A comparison between the sublimation rates of saltating particles and suspended particles of snow.
Mentions: Bintanja25 studied the relationship between the surface and snowdrift sublimation in the katabatic wind region of the Antarctic ice sheet. He assumed that the vertical distribution of the suspended-particle density obeys the standard power-law relation26 and calculated the snowdrift sublimation rate of suspended snow particles. In this study, the motion equations of wind blowing snow are established to obtain the particle velocity and the vertical distribution of particle number density in the saltation layer. Then, the sublimation rate is calculated using the expression of Thorpe and Mason9 under the same values of model variables associated with particles as used by Bintanja25. For comparison purposes, the results of Bintanja are shown with our results in Figure 3. The snowdrift sublimation of Bintanja is obviously less than ours when the friction velocity is less than 0.525 m/s. In other words, the DSS of saltating particles is greater than that of suspended particles, and the difference between them gradually increases as the friction velocity decreases. When the friction velocity is greater than 0.362 m/s but less than 0.525 m/s, the sublimation rate of saltating particles ranges from 36.3 W m−2 to 51.3 W m−2, i.e. 1.1 mm d−1 SWE to 1.6 mm d−1 SWE, indicating that the snowdrift sublimation rate in the saltation layer is so considerable that it should be considered. The snowdrift sublimation rate of saltating particles is less than that of the suspended particles only with a very high friction velocity (great than 0.625 m/s). Therefore, DSS in the saltation layer is of significance and should not be neglected in the prediction of DSS. Figure 3 also shows that the snowdrift sublimation rate in the saltation layer increases linearly with the friction velocity, reaching 75.6 W m−2 at a friction velocity of 0.726 m/s.

Bottom Line: Previous studies of drifting snow sublimation have focused on suspended snow, and few have considered saltating snow, which is the main form of drifting snow.The simulated results show 1) the average sublimation rate of drifting snow particles increases linearly with the friction velocity; 2) the sublimation rate gradient with the friction velocity increases with increases in the environmental temperature and the undersaturation of air; 3) when the friction velocity is less than 0.525 m/s, the snowdrift sublimation of saltating particles is greater than that of suspended particles; and 4) the snowdrift sublimation in the saltation layer is less than that of the suspended particles only when the friction velocity is greater than 0.625 m/s.Therefore, the drifting snow sublimation in the saltation layer constitutes a significant portion of the total snow sublimation.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Mechanics on Disaster and Environment in Western China, Lanzhou University, Lanzhou 730000, China.

ABSTRACT
Snow sublimation is an important hydrological process and one of the main causes of the temporal and spatial variation of snow distribution. Compared with surface sublimation, drifting snow sublimation is more effective due to the greater surface exposure area of snow particles in the air. Previous studies of drifting snow sublimation have focused on suspended snow, and few have considered saltating snow, which is the main form of drifting snow. In this study, a numerical model is established to simulate the process of drifting snow sublimation in the saltation layer. The simulated results show 1) the average sublimation rate of drifting snow particles increases linearly with the friction velocity; 2) the sublimation rate gradient with the friction velocity increases with increases in the environmental temperature and the undersaturation of air; 3) when the friction velocity is less than 0.525 m/s, the snowdrift sublimation of saltating particles is greater than that of suspended particles; and 4) the snowdrift sublimation in the saltation layer is less than that of the suspended particles only when the friction velocity is greater than 0.625 m/s. Therefore, the drifting snow sublimation in the saltation layer constitutes a significant portion of the total snow sublimation.

No MeSH data available.


Related in: MedlinePlus