( 3 ) on interannual timescale , the changes in the sh ferrel cell lead to the anti - phase variation of the subtropical high and the circumpolar low , i . e . , the antarctic oscillation ( aao ) ( 3 )南半球ferrel环流圈的异常使绕极低压带和副热带高压带的强度出现了反位相的变化特征，即南极涛动。
3.
The result shows that : the sand - dust storm occured in favorable climate background that is drought and rainless , the tilted trough and mongolia cyclone are the important weather systems that caused the severe sand - dust storm , tilted trough and strong frontal zone caused the mongolia cyclone developed and the clod front strengthened at surface , high jet and ferrel circulation are the main reason that momentum spreaded downward from higher level and frontal zone strengthened on lower level 结果表明：沙尘暴是在干旱少雨的有利的气候背景下产生的。斜压槽和蒙古气旋是触发这次强沙尘暴天气过程的重要的天气系统，高空斜压槽和强锋区促使了地面蒙古气旋的发展和冷锋的加强，诱发沙尘暴天气。高空急流及其下方的ferrel环流起到了高层动量下传和加强低层锋区的重要作用。
