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Advances in Atmospheric Sciences 2024年第3期41卷 509-528页

作者： Guojing LI Dongxiao WANG Changming DONG Jiayi PAN Yeqiang SHU Zhenqiu ZHANG State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Shool of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China School of Geography and Environment Jiangxi Normal UniversityNanchang 330022China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519080China

The variations of the frontogenetic trend of a cold filament induced by the cross-filament wind and wave fields are studied by a non-hydrostatic large eddy simulation. Five cases with different strengths of wind and wave fields are *** results show that the intense wind and wave fields further break the symmetries of submesoscale flow fields and suppress the levels of filament frontogenesis. The changes of secondary circulation directions—that is, the conversion between the convergence and divergence of the surface cross-filament currents with the downwelling and upwelling jets in the filament center—are associated with the inertial oscillation. The filament frontogenesis and frontolysis caused by the changes of secondary circulation directions may periodically sharpen and smooth the gradient of submesoscale flow *** lifecycle of the cold filament may include multiple stages of filament frontogenesis and frontolysis.

关键词： cold filament frontogenesis frontolysis large eddy simulation

frontogenesis,Evolution and the Time Scale of Front Formation

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Advances in Atmospheric Sciences 1998年第2期15卷 100-113页

作者：方娟伍荣生 Severe Mesoscale meteorological Research Laboratory Nanjing University Nanjing

Observational study shows that, in some cases, the frontal structure displays the features of gravitative flows. It seems that the formation of discontinuity is an important problem in the study of the frontogenesis which is usually defined as an increasing of the scalar gradient. In this paper, the characteristic features of air flow with initial imbalance between the wind and the density fields are studied. Much attention is paid on the condition for the formation of discontinuity and its time scale. It is found that the initial distribution of density plays an important role in the formation of the discontinuity which happens in short time duration.

关键词： Front frontogenesis Evolution Time scale

Cold filament frontogenesis and frontolysis induced by thermal convection turbulence using large eddy simulation

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Acta Oceanologica Sinica 2024年第9期43卷 26-34页

作者： Zewen Wu Guojing Li Yunkai He Jintuan Zhang State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China School of Architecture and Electrical Engineering Hezhou UniversityHezhou 542889China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519080China

The frontogenetic processes of a submesoscale cold filament driven by the thermal convection turbulence are studied by a non-hydrostatic large eddy *** results show that the periodic changes in the direction of the cross-filament secondary circulations are induced by the inertial *** change in the direction of the secondary circulations induces the enhancement and reduction of the horizontal temperature gradient during the former and later inertial period,which indicates that the frontogenetical processes of the cold filament include both of frontogenesis and *** structure of the cold filament may be broken and restored by frontogenesis and frontolysis,*** magnitude of the down-filament currents has a periodic variation,while its direction is unchanged with *** coupling effect of the turbulent mixing and the frontogenesis and frontolysis gradually weakens the temperature gradient of the cold filament with time,which reduces frontogenetical intensity and enlarges the width of cold filament.

关键词： cold filament frontogenesis frontolysis thermal convection turbulence large eddy simulation

Effects of surface drag on low-level frontogenesis within baroclinic waves

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Science China Earth Sciences 2007年第2期50卷 306-319页

作者： ZHANG Yi TAN ZheMin Key Laboratory of Mesoscale Severe Weather of Ministry of Education and Department of Atmospheric SciencesNanjing Univer-sityNanjing 210093China

Using a three-dimensional nonhydrostatic mesoscale numerical model (MM5), the evolution and structures of baroclinic waves with and without surface drag in case of dry and moist atmosphere are simulated, with special emphases on the effects of surface drag on the low-level frontal structure and frontogenesis. There are two different effects of surface drag on the low-level frontogenesis in the dry case. On one hand, the surface drag weakens the low-level frontogenesis and less inclined to develop the baroclinic wave due to the dissipation. But on the other hand, the surface drag induces a strong ageostrophic flow, which prolongs the low-level frontogenesis and finally leads to the enhancement of cold front. Compared with the no surface drag case, the surface drag increases the frontal slope espe- cially in the boundary layer, where the front is almost vertical to the surface, and then enhances the prefrontal vertical motion. All these conclusions expanded the analytical theory of Tan and Wu (1990). In the moist atmosphere, the influence of surface drag on frontal rainbands is also obvious. The surface drag weakens the convection, and reduces the energy dissipation near the surface when the initial relative humidity is relatively weak. At this time, the confluence induced post-frontal updrafts moves across the cold front and reinforces the prefrontal convection, which is beneficial to the maintenance of the rainband in cold sector. Given the enhancement of relative humidity, the moist convection domi- nates the low-level frontogenesis while the retardation of surface drag on energy dissipation is not obvious, therefore the effects of surface drag on the low-level frontogenesis and precipitation are re- duced.

关键词： surface drag baroclinic wave frontogenesis diabatic heating frontal rainband

A Generalized frontogenesis Function and Its Application

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Advances in Atmospheric Sciences 2014年第5期31卷 1065-1078页

作者： YANG Shuai GAO Shouting LU Chungu Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of Sciences State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences U.S. National Science Foundation Arlington VA 22230 USA

With the definition of generalized potential temperature, a new generalized frontogenesis function, which is expressed as the Lagrangian change rate of the magnitude of the horizontal generalized potential temperature gradient, is derived. Such a frontogenesis function is more appropriate for a real moist atmosphere because it can reflect frontogenesis processes, in which the atmosphere in a frontal zone is typically characterized by neither completely dry nor uniform saturation. Furthermore, by derivation, the expression of generalized frontogenesis function includes both temperature and humidity gradients, which is different from and superior to the traditional frontogenesis function in moist processes, which also uses equivalent potential temperature. Diagnostic studies of real cases are performed and show that the generalized frontogenesis function in non- uniformly saturated moist atmosphere indeed provides a useful tool for frontogenesis, compared to using the traditional frontogenesis function. The new frontogenesis function can be used in situations involving either a strong temperature or moisture gradient and is closely correlated with precipitation.

关键词： frontogenesis diagnostic analysis case study

Interaction of Mesoscale Convection and frontogenesis

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Advances in Atmospheric Sciences 2004年第5期21卷 814-823页

作者：彭加毅方娟伍荣生 Department of Atmospheric Sciences Nanjing Institute of MeteorologyKey Laboratory of Meteorological Disaster and Environmental VariationNanjing 210044 Department of Atmospheric Sciences Key Laboratory of Mesoscale Severe Weather of Ministry of EducationNanjing UniversityNanjing 210093

On the basis of the MM5 simulation data of the severe storm that occurred over the southeastern part of Hubei province on 21 July 1998, the interaction of mesoscale convection and frontogenesis is dealt with using the thermodynamical equation and frontogenetical function. The results show that the outbreak of the severe storm is closely related to the local frontogenesis. In fact, the interaction between the shearing instability of the low-level jet (LLJ) and the topographic forcing generates an gravity-inertia wave as well as local frontogenesis (the ?rst front), which consequently induce the onset of the severe storm. From then on, owing to the horizontal and vertical advection of the potential temperature, the new frontogenesis (the second front) is formed to the northeast side of the severe storm, which initiates the second rain belt. Meanwhile, a two-front structure emerges over the southeastern part of Hubei province. Accompanied with the further intensi?cation of the convection, the rain droplets evaporation cooling strengthens the ?rst front and weakens the second front, resulting in single front structure over the southeastern part of Hubei province in the period of the strong convection.

关键词： mesoscale convection frontogenesis two-front structure

DIAGNOSIS OF THE DEVELOPMENTAL MECHANISM OF THE EXTRATROPICAL TRANSITION OF A TROPICAL CYCLONE USING POTENTIAL VORTICITY INVERSION OF frontogenesis

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Journal of Tropical Meteorology 2012年第3期18卷 360-368页

作者：周毅肖坤宋辉 Institute of Meteorology PLA University of Science and Technology

This paper diagnoses and analyses the developmental mechanism of a process of extratropical transition of a tropical cyclone which occurred over West Pacific Ocean based on a diagnosis method of potential vorticity inversion of *** study diagnoses quantitatively the role and effect of dynamic influence of westerly cold troughs,middle-latitude baroclinic frontal zones,cyclone cycles and unbalanced wind fields during the different stages of the extratropical transition of a tropical cyclone,and also discusses the interaction between them and the developmental *** results show that there are different developmental mechanisms during each stage of the extratropical transition and the processes are also unbalanced.

关键词： extratropical transition of tropical cyclones frontogenesis potential vorticity mechanism analysis

Evolution and frontogenesis of an Imbalanced Flow- the Influence of Vapor Distribution and Orographic Forcing

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Advances in Atmospheric Sciences 2000年第2期17卷 256-274页

作者：王云峰伍荣生潘益农 Laboratory of Mesoscale Severe Weather Nanjing University Nanjing

If the initial fields are not in geostrophic balance, the adjustment and evolution will occur in the stratified fluid. and the frontogenesis will occur under suitable conditions. The evolution is studied here with a nonhydrostatic fully compressible meso-scale model (Advanced Regional Prediction System, ARPS). Four cases are designed and compared: (i) control experiment: (ii) with different initial temperature gradient; (iii) with vapor distribution; (iv) with orographic forcing. The results show that: (1) there is an inertial oscillation in the evolution of the imbalanced flow with the frequency of the local Coriolis f, and with its amplitude decreasing with time. The stationary balanced state can only be approached as it cannot be reached in the limit duration of time. The energy conversion ratio varies in the range of [0, 1; 3]; (2) the stronger initial temperature gradient can make the final energy conversion ratio higher. and vice versa; (3) suitable vapor distribution is favorable for the frontogenesis. It will bring forward the time of the frontogenesis, strengthen the intensity of the cold front, and influence the final energy conversion ratio; (4) the orographic forcing has an evidently strengthening effect on the frontogenesis. The strengthening effect on the frontogenesis and the influence on the final energy conversion ratio depend on the relative location of the mountain to the cold front.

关键词： evolution frontogenesis inertial oscillation vapor distribution and orographic forcing

Investigation of the Mei-yu Front Using a New Deformation frontogenesis Function

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Advances in Atmospheric Sciences 2015年第5期32卷 635-647页

作者： YANG Shuai GAO Shouting Chungu LU Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of Sciences State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences U.S. National Science Foundation

A new frontogenesis function is developed and analyzed on the basis of a local change rate of the absolute horizontal gradient of the resultant deformation. Different from the traditional frontogenesis function, the newly defined deformation frontogenesis is derived from the viewpoint of dynamics rather than thermodynamics. Thus, it is more intuitive for the study of frontogenesis because the compaction of isolines of both temperature and moisture can be directly induced by the change of a flow field. This new frontogenesis function is particularly useful for studying the mei-yu front in China because mei-yu rainbands typically consist of a much stronger moisture gradient than temperature gradient, and involve large deformation flow. An analysis of real mei-yu frontal rainfall events indicates that the deformation frontogenesis function works remarkably well, producing a clearer mei-yu front than the traditional frontogenesis function based on a measure of the potential temperature gradient. More importantly, the deformation frontogenesis shows close correlation with the subsequent（6 h later） precipitation pattern and covers the rainband well, bearing significance for the prognosis or even prediction of future precipitation.

关键词： deformation frontogenesis precipitation

Climatological Characteristics of frontogenesis and Related Circulations over East China in June and July

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Acta meteorologica Sinica 2013年第2期27卷 144-169页

作者：侯俊管兆勇 Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science & Technology Jiangsu Meteorological Observatory

Based on daily precipitation data from 212 stations in East China and NCEP/NCAR daily global final analysis data in June and July from 2000 to 2010, the climatological characteristics of frontogenesis and related circulations have been analyzed. The results demonstrate that frontogenesis function distributes non- uniformly in East China. The different terms of the kinematic frontogenesis show different intensities and distributions of frontogenesis. The strongest frontogenesis integrated from different kinematic frontogenesis terms is observed in the Jianghuai area. frontogenesis events are separated into four types as per the different shear and convergence types of horizontal wind along the strong frontogenesis band at 850 hPa. The four types include the warm shear type, cold shear type （with two subtypes）, west wind convergence type, and east wind convergence type. The events in different frontogenesis types occur with different frequencies over the past decade. The warm shear type occurs most frequently. Different types of frontogenesis have distinctive horizontal and vertical structures. Strong frontogenesis is featured with 340-K contour of 0se parallel to the frontal zone in the vertical. Varied large-scale circulation patterns manifested in shifted location and strength of cyclone or anticyclone, wind convergence, as well as vertical circulation structure are associated with different types of frontogenesis. Moreover, a strong positive correlation between frontogenesis and precipitation is found, i.e., the stronger the frontogenesis, the more precipitation there is. Daily precipitation related to the warm shear type frontogenesis is the largest, and often occurs inside the frontal zone with the same orientation with the strong frontogenesis belt. The second largest daily precipitation occurs with the cold shear type frontogenesis, and related rainfall is usually observed to the south of the frontal zone, with the rain belt extending northeastward. Precipitat

关键词： frontogenesis circulation pattern precipitation East China boreal summer