沙尘热动力机制与农田防护林抑尘机理

Thermal dynamic mechanism of dust and dust suppression mechanism of farmland shelterbelts

沙尘天气包括尘卷风、扬沙和沙尘暴等起沙扬尘过程,对生态、生产、生活危害很大。近年沙尘暴频繁发生的问题,引发了人们对农田防护林防控沙尘作用的争论。鉴于此,作者重点讨论了强对流沙尘暴形成和发展的热动力作用机制,包括尘卷风及沙尘暴中尘土上升的热动力作用机理、尘土热动力量值、干飑线黑风暴与飑线雹暴升力能量密度等参数的估算,在此基础上,得出了农田防护林防控沙尘暴的机理和作用:(1)减缓地表热力积蓄,摩擦消耗平流和对流能量,有效防止地表风蚀起尘;(2)林网区静风空间能够捕获尘粒、过滤尘土;(3)促进高空含尘气流与近地面乱流交换,使微尘不断进入滞尘空间被过滤。未来应加强尘源地监控、尘土热动力强化风力的正反馈作用以及不同农田防护林配置的抑尘效果研究。

Sand and dust weather includes dust devil,sand and dust storm and other sand and dust processes,which do great harm to ecology,production and life.With the frequent occurrence of dust storms in recent years,especially this year,debates have arisen regarding the role of farmland shelterbelts in preventing and controlling dust storms.In light of this,we focused on discussing the thermodynamic mechanisms of the formation and development of severe convective dust storms,including the thermodynamic effects of dust devils and dust rising in dust storms,the thermodynamic values of dust and the estimation of the lifting energy density of dry squall line black storm and squall line hailstorm,etc.Based on this,we obtained the mechanisms and effects of farmland shelterbelts in preventing and controlling dust storms:(1)slowing down the accumulation of surface heat,dissipating advection and convective heat through friction,effectively preventing surface wind erosion and dust uplift;(2)the static air space within the forest network can capture dust particles and filter dust;(3)promoting the exchange of high-altitude dusty airflows with near-ground turbulent flows,continuously directing micro-dust enters the dust retention spaces for filtration.In the future,it is necessary to strengthen the monitoring of dust source areas,the positive feedback effects of dust thermal dynamics and the dust suppression effect of different farmland shelterbelts configurations.