Introducing the surface properties [initial vortex, ground temperature and surface momentum impact height （SMIH）] for the boundary conditions, dust-devil-scale large eddy simulations （LES） were carried out. Given ...Introducing the surface properties [initial vortex, ground temperature and surface momentum impact height （SMIH）] for the boundary conditions, dust-devil-scale large eddy simulations （LES） were carried out. Given three parameters of initial vortex, ground temperature and the SMIH based on Sinclair＇s observation, the dust devil physical characteristics, such as maximum tangential velocity, updraft velocity, pressure drop in the inner core region, and even reverse flow at the top of the core region, are predicted, and are found to be close to the observations, thus demonstrating the ability of the simulation. The physical characteristics of different modeled dust devils are reproduced and compared to the values predicted by Renno et al.＇ theory. Even for smaller temperature differences or weaker buoyancy, severe dust devils may be formed by strong incipient vortices. It is also indicated that SMIH substantially affects the near-surface shape of terrestrial dust devils.展开更多
The frequent attacks of strong and extraordinarily strong dust devil in the northern China in recent years are closely related to the serious destruction of the vegetation in the region in recent decades, the increasi...The frequent attacks of strong and extraordinarily strong dust devil in the northern China in recent years are closely related to the serious destruction of the vegetation in the region in recent decades, the increasing expansion of the desertification area, the increase of sand sources due to eco environmental deterioration, the warming up of climate and the weakening of the resisting capacity of our natural environment against dust devil. Measures for preventing and controlling dust devil are to improve the eco environment by increasing vegetation, establish a dust devil pre warning system and a dynamic monitoring & forecast system for dust dveil frequent areas, and enhance the enforcement of laws and administrative efforts so as to bring the eco environment construction of dust devil afflicted areas into the orbit of laws.展开更多
文摘Introducing the surface properties [initial vortex, ground temperature and surface momentum impact height （SMIH）] for the boundary conditions, dust-devil-scale large eddy simulations （LES） were carried out. Given three parameters of initial vortex, ground temperature and the SMIH based on Sinclair＇s observation, the dust devil physical characteristics, such as maximum tangential velocity, updraft velocity, pressure drop in the inner core region, and even reverse flow at the top of the core region, are predicted, and are found to be close to the observations, thus demonstrating the ability of the simulation. The physical characteristics of different modeled dust devils are reproduced and compared to the values predicted by Renno et al.＇ theory. Even for smaller temperature differences or weaker buoyancy, severe dust devils may be formed by strong incipient vortices. It is also indicated that SMIH substantially affects the near-surface shape of terrestrial dust devils.
文摘The frequent attacks of strong and extraordinarily strong dust devil in the northern China in recent years are closely related to the serious destruction of the vegetation in the region in recent decades, the increasing expansion of the desertification area, the increase of sand sources due to eco environmental deterioration, the warming up of climate and the weakening of the resisting capacity of our natural environment against dust devil. Measures for preventing and controlling dust devil are to improve the eco environment by increasing vegetation, establish a dust devil pre warning system and a dynamic monitoring & forecast system for dust dveil frequent areas, and enhance the enforcement of laws and administrative efforts so as to bring the eco environment construction of dust devil afflicted areas into the orbit of laws.
