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The Mesoscale Balance and Imbalance and the Corresponding Potential Vorticity Inversion from the View of Helicity
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作者 高守亭 周菲凡 左群杰 《Journal of Meteorological Research》 SCIE CSCD 2016年第4期559-571,共13页
The static balance and the geostrophic balance are the common balances in meteorology.All the synoptic systems and most of the mesoscale systems satisfy the above two balances.However,due to the strong convection and ... The static balance and the geostrophic balance are the common balances in meteorology.All the synoptic systems and most of the mesoscale systems satisfy the above two balances.However,due to the strong convection and non-geostrophic feature,many mesoscale systems usually present as static imbalance,and the quasi-geostrophic approximation is no longer attainable.This paper tried to find out a kind of balance that exists for mesoscale convective system.To do this,the concrete mathematics definitions for balance and imbalance equations were defined.Then,it is proposed that the new balance equation should include the divergence,vorticity,and vertical motion simultaneously,and the helicity equation was a good choice for the basis.Finally,the mesoscale balance and imbalance equations were constructed,as well as a new balance model that was based on the helicity,horizontal divergence,vertical vorticity,continuity,and thermal dynamic equations under same approximations.Moreover,the corresponding potential vorticity(PV)inversion technique was introduced.It was pointed out that by using the PV conservation and the potential temperature conservation,the flows of the mesoscale balance model can be deduced,and their comparison with the real fields would give the degree of the imbalance. 展开更多
关键词 helicity mesoscale balance mesoscale imbalance PV inversion
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Diagnosis of the Secondary Circulation of Tropical Storm Bilis(2006) and the Effects of Convective Systems on Its Track 被引量:1
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作者 余锦华 符昊 +1 位作者 唐盛 盛思伟 《Journal of Meteorological Research》 SCIE 2014年第2期252-267,共16页
We diagnose characteristics of the quasi-balanced flow and secondary circulation(SC) of tropical storm Bilis(2006) using the potential vorticity(PV)-ω inversion method.We further analyze how secondary steering ... We diagnose characteristics of the quasi-balanced flow and secondary circulation(SC) of tropical storm Bilis(2006) using the potential vorticity(PV)-ω inversion method.We further analyze how secondary steering flows associated with mesoscale convective systems affected the track of tropical storm Bilis after it made landfall.The quasi-balanced asymmetric and axisymmetric circulation structures of tropical storm Bilis are represented well by the PV-w inversion.The magnitude of the nonlinear quasi-balanced vertical velocity is approximately 75%of the magnitude simulated using the Weather Research and Forecasting(WRF) model.The SC of Bilis(2006) contained two strong regions of ascending motion,both of which were located in the southwest quadrant of the storm.The first(150-200 km southwest of the storm center) corresponded to the eyewall region,while the second(approximately 400 km southwest of the storm center) corresponded to latent heat release associated with strong precipitation in major spiral rainbands.The SC was very weak in the northeast quadrant(the upshear direction).Dynamical processes related to the environmental vertical wind shear produced an SC that partially offset the destructive effects of the environmental vertical wind shear(by 20%-25%).This SC consisted of upward motion in the southwest quadrant and subsidence in the northeast quadrant,with airflow oriented from southwest to northeast at high altitudes and from northeast to southwest at lower levels.The inverted secondary zonal and meridional steering flows associated with continuous asymmetric mesoscale convective systems were about-2.14 and-0.7 m s^(-1),respectively.These steering flows contributed substantially to the zonal(66.15%) and meridional(33.98%) motion of the storm at 0000 UTC15 July 2006.The secondary steering flow had a significant influence on changing the track of Bilis from southward to northward.The direction of the large-scale meridional steering flow(3.02 m s^(-1)) was opposite to the actual meridional motion(-2.06 m s^(-1)). 展开更多
关键词 PV-ω inversion secondary circulation mesoscale convective systems Bilis' track
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