青藏高原和落基山对气旋的动力影响

DYNAMIC EFFECT OF QINGHAI-XIZANG AND ROCKY MOUNTAINS ON THE LEE CYCLONES

中文摘要:

      本文利用北京气象中心的业务预报模式(B模式),采用全风速调整方案,进行了绕流、爬坡等各种数值试验,研究青藏高原和落基山对气旋的动力影响。结果表明,气流绕青藏高原而行,产生的散度场与东亚的气旋生成区和路径匹配;在青藏高原主体下游,高层辐合,抑制了我国大陆东部的气旋发展。在北美,落基山对大气的动力影响以爬坡为主,由于气流在迎风坡上升,空气绝热冷却,在背风面大规模下沉增温,对流层低层形成暖脊,这对背风锋生和背风气旋的发生发展有着直接的影响;另外爬坡作用也是美国中西部干线形成的主要原因。

英文摘要:

      Using the operational prediction model (B Model) of Beijing Meterological Center,we do some of numerical experiments of crossing and rounding.mountains in all velocity ad justment scheme.We study dynamic effect of Qinghai-Xizang Plateau and Rocky Mountains on the lee cyclones.The results,shpw that due to air flow round Qinghai-Xizang Plateau,divergence is distributed in the shape of confluence which match cyclogenesis area and cyclonic track in the east Asia.In the downstream of Qinghai-Xizang Plateau,convergence of high level of troposphere restrains cyclone development in the east of China continent.1n the Northern America,air flow primarily crosses over Rocky Mountams.Air is adiabatically cooled when it flows upward in the west flank of Rocky Mountains,while air is warmed when it flows downward in the lee side of Rocky Mountains.The fact is important for the lee cyclogenesis and the lee frontogenesis of Rocky Mountains.Air flow crossing over Rocky Mountains is also main cause for forming dryline in the mid-west of United States.