doi:10.1007/s00376-015-5082-y

Bishop C. H., 1996a: Domain-independent attribution. Part I: Reconstructing the wind from estimates of vorticity and divergence using free space green's functions. J. Atmos. Sci., 53, 241- 252.2c7de67aee697eb9351c088b24aec901

http%3A%2F%2Fconnection.ebscohost.com%2Fc%2Farticles%2F9602270524%2Fdomain-independent-attribution-part-i-reconstructing-wind-from-estimates-vorticity-and

http://connection.ebscohost.com/c/articles/9602270524/domain-independent-attribution-part-i-reconstructing-wind-from-estimates-vorticity-andPresents mathematical models for reconstructing wind dynamics from estimates of vorticity and divergence using free space Green's function. Reconstruction technique on discrete data; Accuracy of standard finite-difference estimates of vorticity/divergence; Attribution and wind field representation on Cartesian domains; Application to limited region of the sphere.

Bishop C. H., 1996b: Domain-Independent attribution. Part II: Its value in the verification of dynamical theories of frontal waves and frontogenesis. J. Atmos. Sci., 53, 253- 262.10.1175/1520-0469(1996)053<0253:DIAPII>2.0.CO;2

4ce333d4-8238-4c0e-af9e-7524f06a47b2

17044750f95881eec71c1db228ae93b5

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F252447633_Domain-Independent_Attribution._Part_II_Its_Value_in_the_Verification_of_Dynamical_Theories_of_Frontal_Waves_and_Frontogenesis

http://www.researchgate.net/publication/252447633_Domain-Independent_Attribution._Part_II_Its_Value_in_the_Verification_of_Dynamical_Theories_of_Frontal_Waves_and_FrontogenesisAbstract Theories of frontogenesis and frontal waves describe development in terms of the interaction of a basic state or environmental flow with a frontal flow. The basic-state flow may comprise a large-scale confluent iffluent deformation field and/or an alongfront temperature gradient. The frontal flow is seen as evolving as a result of its interaction with the environmental flow. Such theories make specific predictions about the effect of the basic-state flow on the frontal flow. To test these predictions, counterparts of the basic-state flows and frontal flows used in theoretical models must be extracted from atmospheric data. Here the concept of attribution is used to identify such counterparts. In the present context, attribution refers to the process whereby a part of the wind field is attributed to a part of the vorticity or divergence field. It is mathematically equivalent to the process by which a part of a field of electric potential is associated with an element of total charge density in electrostatics. The counterpart of the frontal flow used in idealized models is identified as that part of the flow attributable to the vorticity and divergence anomalies within the frontal region. The counterpart of the basic-state flow is identified as that part of the flow attributable to vorticity and divergence anomalies outside the frontal region. Applications of the partitioning method are illustrated by diagnosing the flow associated with a North Atlantic front. The way in which the partitioning method may be used to test some theories concerning the effect of large-scale deformation on frontal wave formation is described. The partitioning method's ability to distinguish frontogenesis due to environmental flow from that due to frontal flow is also discussed. The analyzed front is found to lie at an angle to the dilatation axis of the environmental flow. It is argued that this feature must be common to all nonrotating finite length fronts.

Bishop C. H., A. J. Thorpe, 1994a: Frontal wave stability during moist deformation frontogenesis. Part I: Linear wave dynamics. J. Atmos. Sci., 51( 6), 852- 873.10.1175/1520-0469(1994)0512.0.CO;2

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c26d8e95f2f874d77173bfefa7ed8df8

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F249609557_Frontal_Wave_Stability_during_Moist_Deformation_Frontogenesis._Part_I_Linear_Wave_Dynamics

refpaperuri:(12f4cb980b34e15ffe642bf52248033e)

http://www.researchgate.net/publication/249609557_Frontal_Wave_Stability_during_Moist_Deformation_Frontogenesis._Part_I_Linear_Wave_DynamicsAbstract It has been shown that lower tropospheric potential vorticity zones formed during moist deformation frontogenesis will support growing waves if at some time the frontogenesis ceases. In this paper, the ways in which these waves are affected by the frontogenetic process are identified. Observations show that fronts in the eastern Atlantic commonly feature saturated ascent regions characterized by zero moist potential vorticity. Furthermore, in many cases the horizontal temperature gradient in the lowest one to two kilometers of the atmosphere is rather weak. These features are incorporated in an analytical archetype. The dynamical implications of saturated ascent in conditions of zero moist potential vorticity are represented in the model by assuming that adiabatic temperature changes are precisely balanced by diabatic tendencies. The observed small temperature gradient at low levels is represented in the model by taking it to be zero in the lowest two kilometers. Consequently, the forcing of the low-level moist ageostrophic vortex stretching that strengthens the low-level potential vorticity anomaly is confined to middle and upper levels. A semianalytical initial value solution for the linear development of waves on the evolving low-level potential vorticity anomaly is obtained. The waves approximately satisfy the inviscid primitive equations whenever the divergent part of the perturbation is negligible relative to the rotational part. The range of nonmodal wave developments supported by the front is summarized using RT phase diagrams. This analysis shows that the most dramatic effects of frontogenesis on frontal wave growth are due to (a) the increase in time of the potential vorticity and hence potential instability of the flow and (b) the increase in time of the alongfront wavelength relative to the width of the strip. An optimally growing streamfunction wave is described. Finally, a diagnostic technique suitable for identifying small amplitude frontal waves in observational data is described.

Bishop C. H., A. J. Thorpe, 1994b: Frontal wave stability during moist deformation frontogenesis. Part II: The suppression of nonlinear wave development. J. Atmos. Sci., 51( 6), 874- 888.c76e606cc56d3f1a0c3a32245d176832

http%3A%2F%2Fconnection.ebscohost.com%2Fc%2Farticles%2F9501264345%2Ffrontal-wave-stability-during-moist-deformation-frontogenesis-part-ii-suppression-of

http://connection.ebscohost.com/c/articles/9501264345/frontal-wave-stability-during-moist-deformation-frontogenesis-part-ii-suppression-ofAssesses the role of horizontal deformation and the associated frontogenetic ageostrophic circulation in suppressing the development of nonlinear waves. Wave slope and its maximal amplification; Parameter space of maximal amplification; Description and interpretation of the effect of strain on growth; Scale selection.

Bluestein H. B., 1993: Synoptic Dynamic Meteorology in Midlatitudes. Oxford University Press,594 pp.997641b78b6bc966943a20f660d37e09

http%3A%2F%2Fci.nii.ac.jp%2Fncid%2FBA17138163

http://ci.nii.ac.jp/ncid/BA17138163This new, comprehensive textbook for upper-division undergraduate and graduate students of meteorology presents for the first time information that is now considered essential in modern weather forecasting. Based on a successful series of courses taught by the author at the University of Oklahoma, the text carefully examines the foundations of synoptic meteorology, from the analysis of scalar fields to atmospheric kinematics, dynamics, and thermodynamics.

Cai M., 1992: A physical interpretation for the stability property of a localized disturbance in a deformation flow. J. Atmos. Sci., 49( 23), 2177- 2182.10.1175/1520-0469(1992)049<2177:APIFTS>2.0.CO;2

81a0fb4335ad594fc052d11ba3968786

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F249609372_A_physical_interpretation_for_the_stability_property_of_a_localized_disturbance_in_a_deformation_flow

http://www.researchgate.net/publication/249609372_A_physical_interpretation_for_the_stability_property_of_a_localized_disturbance_in_a_deformation_flowABSTRACT

Cai M., M. Mak, 1990: On the basic dynamics of regional cyclogenesis. J. Atmos. Sci., 47( 12), 1417- 1442.10.1175/1520-0469(1990)0472.0.CO;2

d84faed4-addb-44fc-9533-64310c9ff433

afb7d47864e0dfc69338a28528a6ca79

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F234530620_On_the_Basic_Dynamics_of_Regional_Cyclogenesis

refpaperuri:(80b600b5735a23a080817e7b41b18624)

http://www.researchgate.net/publication/234530620_On_the_Basic_Dynamics_of_Regional_CyclogenesisAbstract This paper investigates the dynamics of regional cyclogenesis from the perspective of local instability of a zonally inhomogeneous baroclinic jet streak in a two-layer quasi-geostrophic beta-plane channel model. When such a representative jet streak is embedded in a background uniform vertical shear U T , there are both local and global unstable normal modes. In the absence of such a background shear ( U T = 0), only the local modes are unstable. The shorter the jet is, the fewer local modes would there be. A local mode consists of a group of dominant waves that jointly give rise to a maximum local energy downstream of the jet core. Its existence is independent of the cyclical boundary condition. The growth rate of a local mode diminishes rapidly when the constant part of the basic zonal wind U 0 is increased. A global mode, on the other hand, largely consists of a single wave and its growth rate is much less sensitive to U 0 . These properties are qualitatively similar to those in the WKB solution. The structural characteristics of these modes are identifiable with those of three classes of unstable modes of an observed atmospheric flow reported in Frederiksen and Bell. Our nonmodal analysis shows that a localized disturbance naturally emerges from a zonally unbiased initial state in a relatively short time. The excitation of a local mode within a few days from an initially isolated disturbance also depends strongly upon its initial position relative to the jet core. The two processes that locally generate the perturbation energy depend upon the structural properties of the disturbance relative to the basic thermal and deformation fields. The two processes that redistribute the perturbation energy are the advection of energy by the basic flow and the convergence of energy flux associated with the ageostrophic component of the perturbation. These four processes are comparably important and greatly counteract one another resulting in a net intensification of a disturbance centered downstream of the jet core. The feedback effects of the most unstable mode on the basic flow resemble the observed geopotential tendencies induced by the transient eddies. The feedback results of this analysis differ noticeably from the WKB counterparts.

Cui X. P., G. X. Wu, and S. T. Gao, 2002: Numerical simulation and isentropic analysis of frontal cyclones over the western Atlantic Ocean. Acta Meteorologica Sinica, 60( 4), 385- 399. (in Chinese)10.1002/mop.10502

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5584200248

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http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-QXXB200204000.htm

http://en.cnki.com.cn/Article_en/CJFDTOTAL-QXXB200204000.htmFrontal cyclogenesis is a widespread weather phenomenon. In spite of the marked improvements in the study of this kind of phenomenon, many problems ramain. Our understanding and prediction of this type of mesoscale vortex is still hampered by (1)the lack of high-resolution data and (2)the absence of theoretical models. This kind of understanding and forecast is still among the most serious challenges to atmospheric scientists. Here by using PSU/NCAR MM5 mesoscale model, a 60-h simulation is performed to reproduce a frontal cyclogenesis over the Western Atlantic Ocean during March 13-15, 1992. Beginning with Slantwise Vorticity Development(SVD), the genesis ,development and propagation are studied by using high-resolution model output in the context of slantwise isentropic surface. And inspiring results are received. The model reproduces well the genesis, track and intensity of the cyclones, their associated thermal structure as well as their surface circulation. The major cyclone(M) deepens 45hPa in the all 60 h and 12hPa in 6 h from 36 to 42(model time) and 27hPa in 24 h from 36 to 60(model time). Profile and isentropic analysis tell us that the cyclogenesis is in very close relation with slantwise isentropic surface; The cyclones always superpose with the core of neutral convection stability with nearly vertical isentropic surface, which coincides with what SVD says.Beginning with Slantwise Vorticity Development(SVD),the development and propagation of the oceanic frontal cyclone are studied by using high-resolution model output in the context of slantwise isentropic surface.The results show that the frontal cyclone deepens rapidly by interaction with large-scale environment after occurring over ocean with weak hydrostatic stability; SVD theory can well translate the development and propagation, which is closely related with slantwise isentropic surface. The downstream slantwise upsliding movement and declination of isentropic surface make vorticity develop(USVD) under favorable conditions ( C D0, here C D is SVD index),and result in the moving and development of cyclone.

Charney J. G., 1947: The dynamics of long waves in a baroclinic westerly current. J. Meteor., 4, 136- 162.10.1175/1520-0469(1947)0042.0.CO;2

ec38cceb1cb5771f96e1fabd0a960fad

http%3A%2F%2Fwww.ams.org%2Fmathscinet-getitem%3Fmr%3D22136

http://www.ams.org/mathscinet-getitem?mr=22136Abstract Previous studies of the long-wave perturbations of the free atmosphere have been based on mathematical models which either fail to take properly into account the continuous vertical shear in the zonal current or else neglect the variations of the vertical component of the earth's angular velocity. The present treatment attempts to supply both these elements and thereby to lead to a solution more nearly in accord with the observed behavior of the atmosphere. By eliminating from consideration at the outset the meteorologically unimportant acoustic and shearing-gravitational oscillations, the perturbation equations are reduced to a system whose solution is readily obtained. Exact stability criteria are deduced, and it is shown that the instability increases with shear, lapse rate, and latitude, and decreases with wave length. Application of the criteria to the seasonal averages of zonal wind suggests that the westerlies of middle latitudes are a seat of constant dynamic instability. The unstable waves are similar in many respects to the observed perturbations: The speed of propagation is generally toward the east and is approximately equal to the speed of the surface zonal current. The waves exhibit thermal asymmetry and a westward tilt of the wave pattern with height. In the lower troposphere the maximum positive vertical velocities occur between the trough and the nodal line to the east in the pressure field. The distribution of the horizontal mass divergence is calculated, and it is shown that the notion of a fixed level of nondivergence must be replaced by that of a sloping surface of nondivergence. The Rossby formula for the speed of propagation of the barotropic wave is generalized to a baroclinic atmosphere. It is shown that the barotropic formula holds if the constant value used for the zonal wind is that observed in the neighborhood of 600 mb.

Davies H. C., J. C. Müller, 1988: Detailed description of deformation-induced semi-geostrophic frontogenesis. Quart. J. Roy. Meteor. Soc., 114, 1201- 1219.10.1002/qj.49711448303

386ed13fdb8409aba9d21b24db230c7e

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.49711448303%2Fcitedby

http://onlinelibrary.wiley.com/doi/10.1002/qj.49711448303/citedbyA variant of the classical deformation-induced surface frontogenesis problem is studied in the semigeostrophic limit. The particular flow system examined is the response of a baroclinic, semi-infinite, stratified, uniform potential vorticity atmosphere to an imposed deformation flow field.

Deng Q. H., 1986: The deformation field in the planetary boundary layer and heavy rainfall. Journal of Academy of Meteorological Science, 1, 165- 174. (in Chinese)a2f179a9359d49c55970efe5410ab864

http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTotal-YYQX198602006.htm

http://en.cnki.com.cn/Article_en/CJFDTotal-YYQX198602006.htmIn this paper,a statistical analysis was made on heavy rainfalls occurring in HubeiProvince and the deformation field in the planetary boundary layer during Meiyu period of1979—1981.It is found that heavy rainstorms are closely related to deformation field inthe planetary boundary layer.Analyzing the deformation field in the planetary boundarylayer gives a criterion for the movement and development of low pressure systems aswell as an indication for the forecasting of heavy rain area in 12—24hours.

Eady E. T., 1949: Long waves and cyclone waves. Tellus, 1, 33- 52.10.3402/tellusa.v1i3.8507

db89b19bc99767c1a89ac7525c7b4d31

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1111%2Fj.2153-3490.1949.tb01265.x%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1111/j.2153-3490.1949.tb01265.x/abstractAbstract By obtaining complete solutions, satisfying all the relevant simultaneous differential equations and boundary conditions, representing small disturbances of simple states of steady baroclinic large-scale atmospheric motion it is shown that these simple states of motion are almost invariably unstable. An arbitrary disturbance (corresponding to some inhomogeneity of an actual system) may be regarded as analysed into “components” of a certain simple type, some of which grow exponentially with time. In all the cases examined there exists one particular component which grows faster than any other. It is shown how, by a process analogous to “natural selection”, this component becomes dominant in that almost any disturbance tends eventually to a definite size, structure and growth-rate (and to a characteristic life-history after the disturbance has ceased to be “small”), which depends only on the broad characteristics of the initial (unperturbed) system. The characteristic disturbances (forms of breakdown) of certain types of initial system (approximating to those observed in practice) are identified as the ideal forms of the observed cyclonc waves and long waves of middle and high latitudes. The implications regarding the ultimate limitations of weather forecasting are discussed.

Elhmaidi D., A. Provenzale, T. Lili, and A. Babiano, 2004: Stability of two-dimensional vorticity filaments. Physics Letters A, 333, 85- 90.10.1016/j.physleta.2004.10.033

19954e44027e5efc59b64270747d9d41

http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0375960104014768

http://www.sciencedirect.com/science/article/pii/S0375960104014768We discuss the results of a numerical study on the stability of two-dimensional vorticity filaments around a circular vortex. We illustrate how the stability of the filaments depends on the balance between the strain associated with the far field of the vortex and the local vorticity of the filament, and we discuss an empirical criterion for filament stability.

Farrell B. F., 1989: Transient development in confluent and diffluent flow. J. Atmos. Sci., 46, 3279- 3288.10.1175/1520-0469(1989)046<3279:TDICAD>2.0.CO;2

6165bcb60a3c4d920e027f24f4bb0a5a

http%3A%2F%2Fwww.ams.org%2Fmathscinet-getitem%3Fmr%3D1021134

http://www.ams.org/mathscinet-getitem?mr=1021134Abstract Explaining the growth of disturbances superimposed on mean flows is a central problem in meteorology. Most widely studied models of the development process involve perturbations to shear flows with shear restricted to the meridional direction. Recently the importance of zonal variation of the mean flow was recognized and the study of shear flows extended to include zonal variation in shear. These studies found that the eigenfunctions associated with unstable modes in the simple shear problem are highly sensitive to zonal variation of the mean flow. However, there also exists another mechanism for development in a zonally inhomogeneous flow field: transient growth not associated with exponential instability. Properly configured perturbations exhibit transient growth in deformation fields associated with regions of confluence and diffluence at rates comparable to development in shear flow. In this work analytic solution of the linear initial value problem for the barotropic vorticity equation in deformation flow is used to construct local perturbations that undergo rapid transient development. Implications for cyclogenesis and block formation are discussed.

Gao S. T., S. Yang, M. Xue, and C. M. Cui, 2008: Total deformation and its role in heavy precipitation events associated with deformation-dominant flow patterns. Adv. Atmos. Sci.,25(1), 11-28, doi: 10.1007/s00376-008-0011-y.10.1007/s00376-008-0011-y

e383b57ebf09e15a790463659720f7cb

http%3A%2F%2Fd.wanfangdata.com.cn%2FPeriodical_dqkxjz-e200801002.aspx

http://d.wanfangdata.com.cn/Periodical_dqkxjz-e200801002.aspx

Holton J. R., 2004: Circulation and vorticity. An Introduction to Dynamic Meteorology, Elsevier Academic Press, 84- 114.10.1088/0034-4885/5/1/309

4a9a7c5124abd58d53e17ed1661afa88

http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FB9780750663151500166

http://www.sciencedirect.com/science/article/pii/B9780750663151500166Several charts are presented that show meteorology data and figures, including annual climatological data for U.S. cities in 2008, record temperature by U.S. state, and hurricane and tornado classifications.

Hoskins B. J., F. P. Bretherton, 1972: Atmospheric frontogenesis models: Mathematical formulation and solution. J. Atmos. Sci., 29, 11- 37.10.1175/1520-0469(1972)0292.0.CO;2

583547bc04a775d3c865a1ee9f6dada4

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F243775183_Atmospheric_Frontogenesis_Models_Mathematical_Formulation_and_Solution

http://www.researchgate.net/publication/243775183_Atmospheric_Frontogenesis_Models_Mathematical_Formulation_and_SolutionAbstract The approximation of geostrophic balance across a front is studied. Making this approximation, an analytic approach is made to a frontogenesis model based on the classic horizontal deformation field. Kelvin's circulation theorem suggests the introduction of a new independent variable in the cross-front direction. The problem is solved exactly for a Boussinesq, uniform potential vorticity fluid. Non-Boussinesq, non-uniform potential vorticity, latent heat, and surface friction effects are all studied. Using a two-region fluid we model the effects of confluence near the tropopause. A similar approach is made to the appearance of fronts in the finite-amplitude development of the simplest Eady wave; this is also solved analytically. Based on the surface fronts produced by these models, we give a general model of a strong surface front. There is a tendency to form discontinuities in a finite time.

Jiang Y. Q., 2011: Study on the dynamic mechanism of formation of mesoscale weather systems triggered by wind perturbations. Ph.D dissertation, Nanjing University, 156 pp.

Jiang Y. Q., Y. Wang, Z. G. Zhou, M. Lü, and J. Luo, 2011: Interaction index of vortex and deformation field. Journal of PLA University of Science and Technology (Natural Science Edition), 12( 6), 685- 689. (in Chinese)87945211899db4de65977c82eefec68a

http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-JFJL201106026.htm

http://en.cnki.com.cn/Article_en/CJFDTOTAL-JFJL201106026.htmTo analyze the short-term change of the intensity and the moving track and speed of the vortex in the deformation field,an interaction index of vortex and deformation field(VDI) was presented.The background pattern of a heavy rainfall event caused by a tropical depression(TD) during 5-6 August 2001 was analyzed with a digital filter compositing method based on Lanczos window function.It is shown that a col field forms as the strong Western Pacific subtropical high is splitting over eastern China.The TD intensifies as it is moving into the col field.Because the higher VDI which is favor of the development of TD represents the stronger interaction of the TD and the col field,the TD may move toward the high VDI region,so the VDI center can be taken as an indication of the moving direction of the TD.Furthermore,the distance between the TD center and the VDI center is also an indication of the moving speed of the TD.The bigger the size of distance,the quicker the TD moves.

Keyser D., R. A. Anthes, 1982: The influence of planetary boundary layer physics on frontal structure in the Hoskins-Bretherton horizontal shear model. J. Atmos. Sci., 39, 1783- 1802.10.1175/1520-0469(1982)039<1783:TIOPBL>2.0.CO;2

106a5d3ff77d233047e9c52fa5f2f147

http%3A%2F%2Fonlinelibrary.wiley.com%2Fresolve%2Freference%2FADS%3Fid%3D1982JAtS...39.1783K

http://onlinelibrary.wiley.com/resolve/reference/ADS?id=1982JAtS...39.1783KA series of numerical experiments with the Hoskins-Bretherton horizontal shear model of frontogenesis in an, amplifying, two-dimensional baroclinic wave is performed. The analytic solutions from the Boussinesq, semi-geostrophic model provide initial conditions for numerical integrations with a two-dimensional, dry version of the fully compressible, hydrostatic primitive equation (PE) model of Anthes and Warner with 40 km horizontal resolution. The PE model is integrated 1) without planetary boundary layer (PBL) physics; 2) with a one-layer bulk-drag scheme; and 3) with a high-vertical-resolution PBL model. The lower boundary is thermally insulated in order to isolate the effect of the internal mixing of heat in the PBL.The simulation with the high-resolution PBL physics resolves several realistic features including 1) a narrow updraft at the top of the PBL above the sea-level pressure trough at the warm edge of the frontal zone; 2) a stable layer capping the PBL to the rear of the frontal zone; and 3) slightly unstable or neutral lapse rates in the PBL behind the front and stable lapse rates in the PBL ahead of the front. A diagnostic analysis of the frontogenesis indicates that the fine structure resulting from adding PBL physics can be attributed to the frictionally driven, ageostrophic inflow in the PBL toward the surface pressure trough in which the frontal zone is located. A finding of particular interest is that the stability patterns in the PBL on either side of the front evolve independently of sensible heating at the surface.

Keyser D., M. J. Reeder, and R. J. Reed, 1988: A Generalization of Petterssen's Frontogenesis Function and Its Relation to the Forcing of Vertical Motion. Mon. Wea. Rev., 116, 762- 781.10.1175/1520-0493(1988)1162.0.CO;2

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http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F23873940_A_generalization_of_Petterssen%27s_frontogenesis_function_and_its_relation_to_the_forcing_of_vertical_motion

http://www.researchgate.net/publication/23873940_A_generalization_of_Petterssen's_frontogenesis_function_and_its_relation_to_the_forcing_of_vertical_motionAbstract Petterssen' frontogenesis equation relates the Lagrangian rate of change of the magnitude of the horizontal potential temperature gradient, referred to as the frontogenesis function, to invariant kinematic properties of the horizontal velocity field. It is not uncommon in synoptic practice to infer the presence of vertical circulations in frontal regions from the spatial distribution of the scalar frontogenesis function. On the other hand, Hoskins and collaborators have introduced a form of the quasi-geostrophic omega equation in which the dynamical and forcing is proportional to the horizontal divergence of the so-called Q vector. The Q vector is defined as the Lagrangian rate of change following the geostrophic flow of the vector horizontal potential temperature gradient. The Q -vector formalism motivates us to generalize the Petterssen frontogenesis function to apply to the vector horizontal potential temperature gradient. This generalization, referred to as the vector frontogenesis function, consists of introducing an expression for the Lagrangian rate of change of direction of the horizontal potential temperature gradient. In order to investigate quantitatively the relative importance of the magnitude and direction contributions to the vector frontogenesis function, we consider three analytical examples. These examples describe the evolution of a potential temperature field represented initially by a linear band of isentropes situated within specified horizontal wind fields that are nondivergent and steady state. The wind fields respectively are a hyperbolic streamline pattern characterized by pure deformation, a meridional wind field varying only in the zonal direction, and an axisymmetric vortex. In each of these examples, it is found that the Lagrangian rates of change of the magnitude and direction of the potential temperature gradient are comparable. In order to explore the dynamical implications of this finding, we separate the Q -vector forcing into contributions consisting of the magnitude and direction components of the vector frontogenesis function. The outcome of this partitioning suggests a possible dynamical basis for isolating vertical circulations associated with frontal zones in three-dimensional baroclinic disturbances: the frontal circulation is related to the magnitude component of the Q vector, whereas the background circulation (that associated with the baroclinic disturbance) is related to the direction component. Consequently, the proposed partitioning of the Q vector appears to lend dynamical support to adopting the scalar frontogenesis function as a qualitative indicator of frontal circulations, provided that these circulations are understood to constitute only a component of the total vertical motion field.

Kuo H. L., 1949: Dynamics instability of two-dimensional non-divergent flow in a barotropic atmosphere. J. Meteor., 6, 105- 122.c7db1477-b194-468f-b378-d9ba1b7395b1

cd0ea3d06082e05aee3e721b7db86b90

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F265981594_Barotropic_instability_of_two-dimensional_non-divergent_flow_in_the_atmosphere

http://www.researchgate.net/publication/265981594_Barotropic_instability_of_two-dimensional_non-divergent_flow_in_the_atmosphere

Li Y., L. S. Chen, and X. T. Lei, 2005: Moisture potential vorticity analysis on the extratropical transition processes of Winnie (1997) and Bilis (2000). Journal of Tropical Meteorology, 21( 2), 142- 152. (in Chinese)10.1360/biodiv.050028

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http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTotal-RDQX200502004.htm

refpaperuri:(9592b3170ea89d982756150a69abc8ed)

http://en.cnki.com.cn/Article_en/CJFDTotal-RDQX200502004.htmTyphoon Winnie(9711) and Bilis(0010) underwent extratropical transition (ET) over Chinese mainland but only Winnie re-intensified as an extratropical system. Their ET processes were examined and compared in terms of the Moisture Potential Vorticity u ( m P ) perspective. Results show that Winnie enters mid-latitude zone and couples with an upper trough during its ET. Bilis also approaches an upper trough but decouples with it. ET re-intensification is related to the interactions between typhoon remnant circulation and lower layer front zone and m P anomaly downward transported from the upper troposphere. Especially, slantwise vorticity development caused by the increase of moist baroclinicity is an main factor responsible for Winnie re-intensification. However, there is no frontal zone occurring in Bilis鈥檚 remnant circulation and downward transportation of the upper m P anomaly is weak.

Mak M., 1991: Dynamics of an atmospheric blocking as deduced from its local energetics. Quart. J. Roy. Meteor. Soc., 117, 477- 493.10.1002/qj.49711749904

0927dd994cf529fb0205415a142a6536

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.49711749904%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1002/qj.49711749904/abstractAbstract This paper reports an analysis of the roles of temporal scale interactions (seasonal, intraseasonal and high-frequency components) in the generation and maintenance of a pronounced block over the North Atlantic that lasted for three weeks in February 1983. This blocking disturbance had a distinct dipole structure initially oriented in an east-west direction downstream from a strongly diffluent south-west-north-east oriented seasonal jet. Although it has an equivalent barotropic structure, there is a well-defined vertical velocity field with ascending (descending) motion on its western (eastern) flank. As it develops, matures and decays, it rotates systematically in a clockwise direction. The contributions from the various temporal scale interactions to the episodal average local energetics of this block are evaluated. There are five comparably important processes controlling the intensity, configuration, and evolution of the block. The synoptic eddy-straining mechanism proposed by Shutts is manifested in three energetics terms, of which one is found to be particularly large. The blocking disturbance also barotropically extracts kinetic energy at a significant rate from the seasonal diffluent jet under the influence of the latter's strong deformation field. The pressure work process, the baroclinic conversion process, and above all, the nonlinear dynamics of the blocking disturbance itself are quantitatively important in redistributing the energy within the blocking region. The effects of the diabatic and subgridscale processes are found, as residues, to be substantially dissipative on the block.

Mak M., M. Cai, 1989: Local barotropic instability. J. Atmos. Sci., 46, 3289- 3311.36098dea-8394-4887-aa29-799495879cd3

09e5f4fa74510a3ccfe700282d1c88e1

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F234539544_Local_Barotropic_Instability

refpaperuri:(f5e9dd68688a0438f76ccae9f19f75bf)

http://www.researchgate.net/publication/234539544_Local_Barotropic_Instability

Meng W. G., A. Y. Wang, J. N. Li, R. Q. Feng, and E. B. Hou, 2004: Moist potential vorticity analysis of the heavy rainfall and mesoscale convective systems in South China. Chinese J. Atmos. Sci., 28( 3), 330- 341. (in Chinese)6b513eff-d3b2-42e0-8f02-c5c1155cde9f

0215ac06e8a96bc7b12cda39cd0ae104

http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-DQXK200403001.htm

refpaperuri:(871ca2f101da3d6a8f547efdaed0e607)

http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQXK200403001.htmBy using the MM5 model outputs of a successful numerical simulation on a South China heavy rainfall event and the mesoscale convective system (MCS) occurred during 23锝24 May 1998, the development of the heavy rainfall and MCS have been investigated in terms of moist potential vorticity principle and slantwise vorticity development theory The results show that, on the slantwise moist isentropic surface, areas with high pressure and positive moist potential vorticity are favorable for the development of heavy rainfall and MCS As the cold air slide down along the moist isentropic surface and confluence with the slantwise upward motion warm and moist air with high convective available potential energy values, both of them experience a stability decreasing process, and lead to cyclonic vorticity development Over deep convection area, the atmosphere exhibits the signature of conditional symmetric instability, and MCS is characterized by slantwise upward motion As for the slantwise of moist isentropic surface, the increase in vertical shear of horizontal wind or enhancement in moist baroclinity also resulted in the increase of vertical vorticity and the development of MCS Finally in the article, a physical conceptual model about the development of heavy rainfall and MCS over South China was presented

Moon Y., D. S. Nolan, 2015: Spiral rainbands in a numerical simulation of Hurricane Bill (2009). Part II: Propagation of inner rainbands. J. Atmos. Sci., 72, 191- 215.10.1175/JAS-D-14-0056.1

e16bc3ebe74d8ba64a7f93cdda74dbac

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F273193041_Spiral_Rainbands_in_a_Numerical_Simulation_of_Hurricane_Bill_%282009%29._Part_II_Propagation_of_Inner_Rainbands%3Fev%3Dauth_pub

http://www.researchgate.net/publication/273193041_Spiral_Rainbands_in_a_Numerical_Simulation_of_Hurricane_Bill_(2009)._Part_II_Propagation_of_Inner_Rainbands?ev=auth_pubAbstract This is the second part of a study that examines spiral rainbands in a numerical simulation of Hurricane Bill (2009). This paper evaluates whether the propagation of inner rainbands in the Hurricane Bill simulation is consistent with previously proposed hypotheses. Results indicate that the propagation of inner rainbands is not consistent with gravity waves, vortex Rossby waves, or squall lines. An alternative hypothesis is offered, arguing that inner rainbands are simply convective clouds that are advected by the rapidly rotating tropical cyclone wind field while being deformed into spiral shapes. A summary and a discussion of the results of both Parts I and II are provided.

Petterssen S., 1956: Weather Analysis and Forecasting Vol. I: Motion and Motion Systems. McGraw-Hill,428 pp.

Renfrew I. A., A. J. Thorpe, and C. H. Bishop, 1997: The role of the environmental flow in the development of secondary frontal cyclones. J. Atmos. Sci. , 123, 1653- 1675.10.1002/qj.49712354210

f0c6ccaa9e8c181df8422748ecad8718

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.49712354210%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1002/qj.49712354210/abstractAbstract The impact of the environmental flow on the development of secondary frontal cyclones is investigated. Several case-studies are examined as examples of secondary frontal-cyclone events observed in the North Atlantic-western Europe sector. A simple measure of growth is defined to chart their development. The vorticity attribution technique of Bishop is utilized to calculate the action of the large-scale (environmental) flow on the fronts. In particular the environmental along-front stretching—shown to be important in theoretical models of frontal instabilities—is calculated. The role of the environmental deformation appears to be crucial: as part of a baroclinic life cycle, stretching deformation acts to build up a front but suppress along-front waves; if the stretching rate diminishes, barotropic instabilities may then break out. Diagnostics are examined to try to ascertain the growth mechanisms at work in each frontal-cyclone case. A range of values for the commonly prescribed deformation-frontogenesis and shearing-frontogenesis parameters are calculated.

Rivière G., A. Joly, 2006a: Role of the low-frequency deformation field on the explosive growth of extratropical cyclones at the jet exit. Part I: Barotropic critical region. J. Atmos. Sci., 63, 1965- 1981.

Rivière G., A. Joly, 2006b: Role of the low-frequency deformation field on the explosive growth of extratropical cyclones at the jet exit. Part II: Baroclinic critical region. J. Atmos. Sci., 63, 1982- 2006.10.1175/JAS3729.1

07ee4af4-0db8-4eb6-89e1-6aa204ee50ca

a8d779b1335da7c9de6dcdc5b9d7c93a

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F259324283_Role_of_the_Low-Frequency_Deformation_Field_on_the_Explosive_Growth_of_Extratropical_Cyclones_at_the_Jet_Exit._Part_I_Barotropic_Critical_Region

refpaperuri:(19053d567a8c753a6efba2a26b70d217)

http://www.researchgate.net/publication/259324283_Role_of_the_Low-Frequency_Deformation_Field_on_the_Explosive_Growth_of_Extratropical_Cyclones_at_the_Jet_Exit._Part_I_Barotropic_Critical_RegionBy using new theoretical results on perturbation growth in spatially and temporally complex quasigeostrophic flows, this paper investigates the role of the large-scale deformation field on extratropical cyclones and especially on their explosive growth in the jet-exit region. Theoretical ideas are tested by decomposing the atmospheric flow into a high- and a low-frequency part and by analyzing four-dimensional variational data assimilation (4DVAR) reanalysis data of the Fronts and Atlantic Storm-Track Experiment (FASTEX) during February 1997 as well as reanalysis data for the end of December 1999. Regions where the low-frequency deformation magnitude is greater than the absolute value of the low-frequency vorticity are shown to correspond to regions where synoptic disturbances at the same level tend to be located. These regions in the upper troposphere are intrinsically related to the horizontal inhomogeneities of the low-frequency large-scale upper-tropospheric jet but cannot be detected by looking separately at the deformation or vorticity. Transitions from one such large-scale region to the next furthermore can be accompanied by a sudden change of the dilatation axes orientation: this combination defines a barotropic critical region (BtCR). Reasons why a BtCR is a specific place where barotropic development is likely to occur are exposed. Two very differently located BtCR regions in two apparently similar zonal-like weather regimes are shown to be the preferred regions where synoptic eddies tend to cross the jet from the south to the north. BtCRs are also special regions where constructive association between barotropic and baroclinic processes is favored, indeed constrained to cooperate. This is illustrated through the detailed analysis of the last growth stage of Intensive Observation Period 17 (IOP17) of FASTEX. It happens precisely around a BtCR area located in the jet-exit region. Two processes explain this IOP17 development; one involves the barotropic generation rate resulting from the low crossing the BtCR and the other one is baroclinic interaction, which is strongly maintained far away from the baroclinicity maximum because of the new favorable baroclinic configuration resulting from the first process.

Rozoff C. M., W. H. Schubert, B. D. McNoldy, and J. P. Kossin, 2006: Rapid filamentation zones in intense tropical cyclones. J. Atmos. Sci., 63, 325- 340.10.1175/JAS3595.1

f5d2d9babcf3f8effffcd16c72341b6b

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F253655601_Rapid_Filamentation_Zones_in_Intense_Tropical_Cyclones

http://www.researchgate.net/publication/253655601_Rapid_Filamentation_Zones_in_Intense_Tropical_CyclonesAbstract Intense tropical cyclones often possess relatively little convection around their cores. In radar composites, this surrounding region is usually echo-free or contains light stratiform precipitation. While subsidence is typically quite pronounced in this region, it is not the only mechanism suppressing convection. Another possible mechanism leading to weak-echo moats is presented in this paper. The basic idea is that the strain-dominated flow surrounding an intense vortex core creates an unfavorable environment for sustained deep, moist convection. Strain-dominated regions of a tropical cyclone can be distinguished from rotation-dominated regions by the sign of S 2 1 + S 2 2 61 ζ 2 , where S 1 = u x 61 υ y and S 2 = υ x + u y are the rates of strain and ζ = υ x 61 u y is the relative vorticity. Within the radius of maximum tangential wind, the flow tends to be rotation-dominated ( ζ 2 > S 2 1 + S 2 2 ), so that coherent structures, such as mesovortices, can survive for long periods of time. Outside the radius of maximum tangential wind, the flow tends to be strain-dominated ( S 2 1 + S 2 2 > ζ 2 ), resulting in filaments of anomalous vorticity. In the regions of strain-dominated flow the filamentation time is defined as τ fil = 2( S 2 1 + S 2 2 61 ζ 2 ) 611/2 . In a tropical cyclone, an approximately 30-km-wide annular region can exist just outside the radius of maximum tangential wind, where τ fil is less than 30 min and even as small as 5 min. This region is defined as the rapid filamentation zone. Since the time scale for deep moist convective overturning is approximately 30 min, deep convection can be significantly distorted and even suppressed in the rapid filamentation zone. A nondivergent barotropic model illustrates the effects of rapid filamentation zones in category 1–5 hurricanes and demonstrates the evolution of such zones during binary vortex interaction and mesovortex formation from a thin annular ring of enhanced vorticity.

Shutts G. J., 1983: The propagation of eddies in diffluent jet-streams: Eddy vorticity forcing of "blocking" flow fields. Quart. J. Roy. Meteor. Soc., 109, 737- 761.be53ba0f-2a54-4b1e-9a7c-78d761405086

e160dd757d20139de33816a5fbc74aca

http%3A%2F%2Fciteseer.ist.psu.edu%2Fshowciting%3Fcid%3D4439989

refpaperuri:(405d7dfc484c19a6d8e0d3522c43d469)

http://citeseer.ist.psu.edu/showciting?cid=4439989

Spensberger C., T. Spengler, 2014: A new look at deformation as a diagnostic for large-scale flow. J. Atmos. Sci., 71, 4221- 4234.4718137e2807d486774cd37cc3c98704

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F270719738_A_New_Look_at_Deformation_as_a_Diagnostic_for_Large-Scale_Flow

http://www.researchgate.net/publication/270719738_A_New_Look_at_Deformation_as_a_Diagnostic_for_Large-Scale_Flow

Thomas L. N., 2012: On the effects of frontogenetic strain on symmetric instability and inertia-gravity waves. J. Fluid Mech., 711, 620- 640.10.1017/jfm.2012.416

8d3dea0f-9168-4113-b9c7-490328ccfc63

d0c7da0867971f71e91c62ac76317647

http%3A%2F%2Fjournals.cambridge.org%2Fabstract_S0022112012004168

refpaperuri:(8e2b9f0b17e33a17cc42be2fd240abc8)

http://journals.cambridge.org/abstract_S0022112012004168The dynamics of symmetric instability and two-dimensional inertiagravity waves, depending on the sign of the Ertel potential vorticity and the magnitude of the Richardson number of the geostrophic flow. The kinetic energy (KE) of both types of motion is suppressed by frontogenetic strain due to the vertical shear in the ageostrophic circulation. This is because the perturbation streamlines tilt with the ageostrophic shear causing the disturbances to lose KE via shear production. The effect can completely dampen symmetric instability for sufficiently strong strain even though the source of KE for the instability (the vertical shear in the geostrophic flow) increases with time. Inertiagravity waves play a catalytic role in loss of balance. Given the large amount of KE in low-frequency inertia鈥揼ravity waves and the ubiquitous combination of strain and baroclinic geostrophic currents in the ocean, it is estimated that this mechanism could play a significant role in the removal of KE from both the internal wave and mesoscale eddy fields.

Wang J. Z., S. F. Ma, and Y. H. Ding, 1996: Application of potential vorticity theory to analysis of formative mechanism of torrential rain. Quarterly Journal of Applied Meteorology, 7, 19- 27.7747c6d93c9a52d7285130a0e58538d5

http%3A%2F%2Fqk.cams.cma.gov.cn%2Fjams%2Fch%2Freader%2Fview_abstract.aspx%3Ffile_no%3D19960103

http://qk.cams.cma.gov.cn/jams/ch/reader/view_abstract.aspx?file_no=19960103应用位涡理论，对1991年江淮地区一次特大暴雨过程中位涡及其有关物理量的分布特征进行了分析。结果表明：强降水总是落在干位涡比较小的地方和湿位涡负中心暖气流一侧，它和相对湿位涡的关系更直接。湿位涡斜压部分可清楚地反映湿斜压性对对流不稳定系统所起的作用。大气在湿位涡值比较小的区域对锋生强迫有更强的响应。

Wang X. B., R. S. Wu, 2001: The development of symmetric disturbance superposed on baroclinic frontal zone under the action of deformation field. Acta Meteorologica Sinica, 15( 4), 420- 435.10.3969/j.issn.0894-0525.2001.04.004

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http%3A%2F%2Fwww.cqvip.com%2FMain%2FDetail.aspx%3Fid%3D1001466128

http://d.wanfangdata.com.cn/Periodical_qxxb-e200104004.aspx正 The development of symmetric disturbance superposed on the background field of Hoskins-Bretherton (1972) frontogenesis model is investigated by means of WKBJ approach,It is found thatthe forcing of large-scale deformation,the frontal circulation and the spatial-temporal variations ofstability para

Wang Y. Q., 2008: Rapid filamentation zone in a numerically simulated tropical cyclone. J. Atmos. Sci., 65, 1158- 1181.10.1175/2007JAS2426.1

37786838-0861-40b7-935f-d2b7b8d82fcc

04ad4bbb83fd98f120f9f748be27c0ac

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F249610529_Rapid_Filamentation_Zone_in_a_Numerically_Simulated_Tropical_Cyclone

refpaperuri:(1fd3851a80d683c1fcb8d554a2134afe)

http://www.researchgate.net/publication/249610529_Rapid_Filamentation_Zone_in_a_Numerically_Simulated_Tropical_CycloneAbstract In a recent study, Rozoff et al. proposed a possible mechanism to explain the formation and maintenance of the weak-echo annulus (or moat) outside of the primary eyewall of a tropical cyclone observed in radar images. By this mechanism, the moat is determined to be a region of the strain-dominated flow outside of the radius of maximum wind in which essentially all fields are filamented and deep convection is hypothesized to be highly distorted and even suppressed. This strain-dominated region is defined as the rapid filamentation zone wherein the filamentation time is shorter than the overturning time of deep convection. An attempt has been made in this study to test the hypothesis in a full-physics tropical cyclone model under idealized conditions and to extend the concept to the study of the inner-core dynamics of tropical cyclones. The foci of this paper are the evolution of the rapid filamentation zone during the storm intensification, the potential roles of rapid filamentation in the organization of inner spiral rainbands, and the damping of high azimuthal wavenumber asymmetries in the tropical cyclone inner core. The presented results show that instead of suppressing deep convection, the strain flow in the rapid filamentation zone outside the elevated potential vorticity core provides a favorable environment for the organized inner spiral rainbands, which generally have time scales of several hours, much longer than the typical overturning time scale of individual convective clouds. Although the moat in the simulated tropical cyclone is located in the rapid filamentation zone, it is mainly controlled by the subsidence associated with the overturning flow from eyewall convection and downdrafts from the anvil stratiform precipitation outside of the eyewall. It is thus suggested that rapid filamentation is likely to play a secondary role in the formation of the moat in tropical cyclones. Although the deformation field is determined primarily by the structure of the tropical cyclone, it can have a considerable effect on the evolution of the storm. Because of strong straining deformation, asymmetries with azimuthal wavenumber >4 are found to be damped effectively in the rapid filamentation zone. The filamentation time thus provides a quantitative measure of the stabilization and axisymmetrization of high-wavenumber asymmetries in the inner core by shearing deformation and filamentation.

Wang Z. Q., W. J. Zhu, and A. M. Duan, 2010: A case study of snowstorm in Tibetan Plateau induced by Bay of Bengal storm: Based on the theory of slantwise vorticity development. Plateau Meteorology, 29( 3), 703- 711. (in Chinese)

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mag484262010293703

<FONT face=Verdana>Based on the diagnosis of moist potential vorticity (MPV) and the theory of slantwise vorticity development (SVD), a case study of snowstorm in the Tibetan Plateau induced mainly by Bay of Bengal storm in November 2007 was analyzed. The results show that the interaction of the storm′s spiral cloud band and the down\|sliding dry cold air (positive MPV1 band) over the steep southern fringe of the plateau is the main reason for this synoptic process. Owing to the dense and obvious slantwise isentropic surface, the contribution of negative MPV2 to moist potential vorticity (MPV) is more than MPV1 over the snowfall area where atmosphere is weak stable. It further leads to the sharp growth of SVD. Moreover, negative MPV makes a favorable background of the generation of conditional symmetrical instability. The conditional symmetrical instability is beneficial tothe development of slantwise vorticity, and it is a possible important mechanism for this snowstorm.</FONT>

Weiss J., 1991: The dynamics of enstrophy transfer in two-dimensional hydrodynamics. Physica D: Nonlinear Phenomena, 48, 273- 294.10.1016/0167-2789(91)90088-Q

c0b3962907582201d55af1945172624a

http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2F016727899190088Q

http://www.sciencedirect.com/science/article/pii/016727899190088QIn this paper the qualitative properties of an inviscid, incompressible, two-dimensional fluid are examined. Starting from the equations of motion we derive a series of equations that govern the behavior of the spatial gradients of the vorticity scalar. The growth of these gradients is related to the transfer of enstrophy (integral of squared vorticity) to the small scales of the fluid motion.

Whitaker J. S., R. M. Dole, 1995: Organization of storm tracks in zonally varying flows. J. Atmos. Sci., 52( 8), 1178- 1191.10.1175/1520-0469(1995)0522.0.CO;2

015cdbefd6de48d6449fdbb29a21e90c

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F249608473_Organization_of_Storm_Tracks_in_Zonally_Varying_Flows

http://www.researchgate.net/publication/249608473_Organization_of_Storm_Tracks_in_Zonally_Varying_FlowsAbstract A simple two-layer quasigeostrophic model is employed to investigate the sensitivity of storm tracks to changes in an externally imposed, zonally varying large-scale flow. Zonally asymmetric temperature and horizontal deformation fields are varied systematically in order to compare the effects of baroclinicity and horizontal deformation on storm track dynamics. The sensitivity of the storm tracks to uniform barotropic zonal flows is also examined. The results show two competing processes for storm track organization, one associated with a local maximum in baroclinicity and the other with a local minimum in horizontal deformation. When the equilibrium state consists of a zonally symmetric temperature field and a barotropic stationary wave, the maximum in synoptic-scale transient eddy energy (storm track) is located in the entrance region of the upper jet just downstream of the point of minimum horizontal deformation. As zonal variations in baroclinicity become large (keeping the upper-layer horizontal deformation constant), the storm track shifts to the jet exit region just downstream of the point of maximum baroclinicity. For flows intermediate between the above cases,that is, having weaker zonal variations in baroclinicity and the same upper-layer deformation, two storm track maxima appear, one located in the jet entrance and the other in the jet exit region. The results also indicate that the storm tracks are sensitive to changes in a uniform barotropic zonal flow. The presence of a uniform westerly flow extends the storm track and strengthens eddy activity, while the addition of a uniform easterly flow shortens the storm track and dramatically weakens eddy activity. The changes in the magnitudes of eddy activity appear related to differences in the efficiency of nonlinear barotropic decay processes in weakening the eddies in the jet exit region. Sensitivities of the location of the storm tracks to changes in large-scale flow parameters are well captured by linear calculations, although sensitivities of the strength of the storm tracks are not. For sufficiently strong zonal variations in baroclinicity, two coherent modes of low-frequency variability develop. They are characterized synoptically by 1) a meridional shift, and 2) an extension/contraction as well as a modulation in the strength of the upper-layer jet and storm track.

Wu G. X., 2001: Comparison between the complete-form vorticity equation and the traditional vorticity equation. Acta Meteorologica Sinica, 59( 4), 385- 392. (in Chinese)10.11676/qxxb2001.042

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After a brief review on the deductions of the complete-form vorticity equation and traditional vorticity equation,comparisons between the to equations are made.Particular attentions are paid to the new physical meanings contained in the complete-form vorticity equation.It is revealed the mechanism for vorticity development due to the internal forcing associated with the changes in static stability and baroclinicity (frontogenesis or frontolysis),as well as the external forcing associated with frictional dissipation and diabatic heating.Finaly,the application prospects of the complete-form vorticity equation in weather and climate studies are discussed.

Wu G. X., Y. P. Cai, 1997: Vertical wind shear and down-sliding slantwise vorticity development. Scientia Atmospherica Sinica, 21( 3), 273- 282. (in Chinese)3264bb0d0cc3320d8fc739bb4fbf22e7

http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-DQXK703.002.htm

http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQXK703.002.htmBased upon the conservation property of moist potential vorticity ( P m ) of an adiabatic, frictionless, and saturated atmosphere, the development of vertical vorticity in a moist baroclinic process was discussed. When moist isentropic surfaces are tilted, the application of the traditional “isentropic potential vorticity” (IPV) analysis is limited. A theory of slantwise vorticity development was then developed to investigate the vorticity intensification from a Lagrangian point of view. It was shown that in the area between the south of monsoon front and the north of warm and moist air mass, moist isentropic surfaces are stiff. This area then becomes a favorable region for the development of cyclone and torrential rain. The necessary condition and sufficient condition for slantwise vorticity development are discussed. It is proved that in a convectively unstable and saturated atmosphere, the occurence of slantwise vorticity development must be accompanied by the existence of a low level jet. Application of this theory to a case analyses of typical monsoonal torrential rain shows that the P m analysis, especially the analysis of P m1 (=- g(f+ζ p)e/) and P m2 (=- g×/· pθ e ) at isobaric surfaces in the lower troposphere, is very effective in identifying the occurence of torrential rain, and may be used as a powerful tool for the diagnosis and prediction of torrential rain.

Wu G. X., H. Z. Liu, 1999: Complete form of vertical vorticity tendency equation and slantwise vorticity development. Acta Meteorologica, 57( 1), 1- 15. (in Chinese)3a4ae8ab7aaa06a6a60283e350722c66

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http://www.cmsjournal.net/qxxben/ch/reader/view_abstract.aspx?file_no=19990101&flag=1

Wu G. X., Y. P. Cai, and X. J. Tang, 1995: Moist potential vorticity and slantwise vorticity development. Acta Meteorologica Sinica, 53( 4), 387- 405. (in Chinese)10.11676/qxxb1995.045

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http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-QXXB504.001.htm

http://en.cnki.com.cn/Article_en/CJFDTOTAL-QXXB504.001.htmAn accurate form of the moist potential vorticity (MPV) equation was deduced from a complete set of primitive equations system. It was shown that motion in a saturated atmosphere without diabatic heating and frictional dissipation conserves moist potential vorticity.This property was then used to investigate the development of vertical vorticity in moist baroclinic processes. Results show that in the frame work of moist isentropic coordinate, vorticity development can result from reduction of convective stability, or convergence. or latent heat release in isentropic surfaces. However, the application of the usual analysis of moist isentropic potential vorticity is limitted due to the declination of moist isentropic surfaces, and a theory of slantwise vorticity development based on Z-coordinate and P-coordinate was then proposed. According to this theory, whether the atmosphere is moist symetrically stable or unstable. or convectively stable or unstable. so long as the moist insentropic surface is slantwise the reduction of convective stability, the increase of the vertical shear of horizontal wind or moist baroclinity can result in the increase of vertical vorticity. The larger the declination of the moist isentropes, the more vigorous the deveolopment of vertical vorticity. In a region with a monsoonal front to the north and warm and moist air to the south, or bye the north of front the moist isentropes are very stiff. This is the region most favorable for the development of vorticities and formation of torrential rain.For a case of persistent torrential rain occuriny in the middle and lower reaches of the Yangtze and Huai River in June 12-15, 1991. moist potential vorticity analysis, especially the isobaric analysis of its vertical and horizontal compoments, i e. MPVI and MPV2 respectively, is effective for indentifying synoptic systems not only in middle and high latitudes. but also in the low latitudes and in the lower troposphere. It can serve as a powerful tool for the diagnosis and prediction of torrential rain.

Wu G. X., Y. J. Zheng, and Y. M. Liu, 2013: Dynamical and thermal problems in vortex development and movement. Part II: Generalized slantwise vorticity development. Acta Meteorologica Sinica, 27( 1), 15- 25.10.1007/s13351-013-0102-2

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http://d.wanfangdata.com.cn/Periodical_qxxb-e201301002.aspxThe development of vertical vorticity under adiabatic condition is investigated by virtue of the view of potential vorticity and potential temperature (PV-胃) and from a Lagrangian perspective. A new concept of generalized slantwise vorticity development (GSVD) is introduced for adiabatic condition. The GSVD is a coordinate independent framework of vorticity development (VD), which includes slantwise vorticity development (SVD) when a particle is sliding down the concave slope or up the convex slope of a sharply tilting isentropic surface under stable or unstable condition. The SVD is a special VD for studying the severe weather systems with rapid development of vertical vorticity. In addition, the GSVD clarifies VD and SVD. The criteria for VD and SVD demonstrate that the demand for SVD is much more restricted than the demand for VD. When an air parcel is moving down the concave slope or up the convex slope of a sharply tilting isentropic surface in a stable stratified atmosphere with its stability decreasing, or in an unstable atmosphere with its stability increasing, i.e., its stability 胃 z approaches zero, its vertical vorticity can develop rapidly if its C D is decreasing. The theoretical results are employed to analyze a Tibetan Plateau (TP) vortex (TPV), which appeared over the TP, then slid down and moved eastward in late July 2008, resulting in heavy rainfall in Sichuan Province and along the middle and lower reaches of the Yangtze River. The change of PV 2 contributed to the intensification of the TPV from 0000 to 0600 UTC 22 July 2008 when it slid upward on the upslope of the northeastern edge of the Sichuan basin, since the changes in both horizontal vorticity 畏 s and baroclinity 胃 s have positive effects on the development of vertical vorticity. At 0600 UTC 22 July 2008, the criterion for SVD at 300 K isentropic surface is satisfied, meaning that SVD occurred and contributed significantly to the development of vertical vorticity. The appearance of the stronger signals concerning the VD and SVD surrounding the vortex indicates that the GSVD concept can serve as a useful tool for diagnosing the development of weather systems.

Yang S., S. T. Gao, and C. G. Lu, 2014: A generalized frontogenesis function and its application. Adv. Atmos. Sci.,31(5), 1065-1078, doi: 10.1007/s00376-014-3228-y.

Yang S., S. T. Gao, and C. G. Lu, 2015: Investigation of the Mei-yu front using a new deformation frontogenesis function. Adv. Atmos. Sci.,32(5), 635-647, doi: 10.1007/s00376-014-4147-7.

Yu H., G. X. Wu, 2001: Moist baroclinicity and abrupt intensity change of tropical cyclone. Acta Meteorologica Sinica, 59( 4), 440- 449 (in Chinese).

Zheng Y. J., G. X. Wu, and Y. M. Liu, 2013: Dynamical and thermal problems in vortex development and movement. Part I: A PV-Q view. Acta Meteorologica Sinica, 27( 2), 1- 14.