doi:10.1007/s00376-015-5080-0

Bennetts D. A., B. J. Hoskins, 1979: Conditional symmetric instability-a possible explanation for frontal rainbands. Quart. J. Roy. Meteor. Soc., 105, 945- 962.10.1002/qj.49710544615

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http://onlinelibrary.wiley.com/doi/10.1002/qj.49710544615/pdf

http://onlinelibrary.wiley.com/doi/10.1002/qj.49710544615/pdfABSTRACT In order to study the possible importance of symmetric baroclinic instability in the formation of frontal rainbands, the existing theory is reviewed and the inclusion of the effects of latent heat release attempted. When an atmosphere is rendered symmetrically unstable by latent heat release, it may be said to be conditionally symmetrically unstable. Simple numerical experiments support the extended theory and describe the structure of the finite amplitude cells. These exhibit conditional gravitational instability in preferred linear regions. It is shown that such a gravitational destabilization is possible only when a wet bulb potential vorticity is initially negative. This latter is a necessary and possibly sufficient condition for ‘conditional symmetric instability’ (CSI). Limited comparison with observed frontal rainbands lends some support to the hypothesis that CSI can be a dominant formative mechanism, though more sophisticated numerical modelling and observational studies are required.

Bennetts D. A., J. C. Sharp, 1982: The relevance of conditional symmetric instability to the prediction of mesoscale frontal rainbands. Quart. J. Roy. Meteor. Soc., 108, 595- 602.10.1002/qj.49710845707

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refpaperuri:(3fdbc762226ab81f49ff244800ad41b3)

http://onlinelibrary.wiley.com/doi/10.1002/qj.49710845707/citedbyABSTRACT This paper examines the theory of Conditional Symmetric Instability (Bennetts and Hoskins 1979) and considers its relevance to meso-scale frontal rainbands. The theoretical growth rate of the instability is evaluated from synoptic scale data obtained from a numerical forecast model and compared with observations of the horizontal structure of rainfall observed by radar. One case study is presented in detail and a further 44 cases summarized. Rainbands were observed on 80% of the occasions on which they were predicted.

Charney J. G., 1947: The dynamics of long waves in a baroclinic westerly current. J. Meteor., 4, 135- 162.10.1175/1520-0469(1947)0042.0.CO;2

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refpaperuri:(f3972097a8eb020607c024c13e96b4ee)

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.

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

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

refpaperuri:(7bf56a91e894b596694f28f290093da2)

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.

Gao S. T., 2000: The instability of the vortex sheet along the shear line. Adv. Atmos. Sci.,17, 525-537, doi: 10.1007/s00376-000-0016-7.10.1007/s00376-000-0016-7

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http://link.springer.com/10.1007/s00376-000-0016-7

http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQJZ200004002.htmThe traditional Kelvin -Helmholtz notion of studying the shear instability is not suitable for the case associated with shear line with the strong wind shear in the vortex sheet. Since then, the shear instability becomes theinstability of the vortex sheet. If the velocity is induced by the vortex sheet, the inequalities (161 R r + Ri d )> 0 and U(v,t)> U(A(t)) become the criterion of the vortex sheet instability. This criterion indicates that 1) the disposition of environment field restrains the disturbance developing along the shear line. 2) There exist multi—scale interactions in the unstable process of the shear line. The calculation of the necessary condition for the instability is also presented in this paper.

Gao S. T., Y. S. Zhou, 2001: The instability of the vortex sheet along the horizontal shear line. Acta Meteorologica Sinica, 59, 393- 404. (in Chinese)10.11676/qxxb2001.043

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http://en.cnki.com.cn/Article_en/CJFDTOTAL-QXXB200104001.htmThe traditional Kelvin-Helmholtz notion of studying the shearinst ability is not suitable to the shear line with the strong horizontal wind shear.For this case,the shear line should be considered as the vortex sheet.Since then,the instability of this kind of the shear line becomes the instability of the vortex sheet rather than the traditional shear instability.If the velocity is induced by the vortex sheet,the in equalities, (1-Rv+Rid)>0 and U(y,t)>U(A(t)) become the criterion of the vortex sheet instability.This criterion indicates that the disposition of environment field rest rains the disturbance developing along the shearline,there exist multi-scale interactions between this mesoscale disturbance and environment field.The calculation of the necessary condition for the instability is also presented in this paper.

Hoskins B. J., 1974: The role of potential vorticity in symmetric stability and instability. Quart. J. Roy. Meteor. Soc., 100, 480- 482.10.1002/qj.49710042520

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refpaperuri:(738d6342269840e395a8ff53268f9579)

http://onlinelibrary.wiley.com/doi/10.1002/qj.49710042520/citedbyNo abstract is available for this article.

Liu L., L. K. Ran, Y. S. Zhou, and S. T. Gao, 2014: Analysis on the instability and trigger mechanism of torrential rainfall event in Beijing on 21 July 2012. Chinese J. Atmos. Sci.,39, 583-595, doi: 10.3878/j.issn.1006-9895.1407.14144. (in Chinese)

Lu W. S., H. Y. Shao, 2003: Generalized nonlinear subcritical symmetric instability. Adv. Atmos. Sci.,20, 623-630, doi: 10.1007/BF02915505.10.1007/BF02915505

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http%3A%2F%2Flink.springer.com%2F10.1007%2FBF02915505

refpaperuri:(8bbdd9a6dcb2efca9b8ab3225d7f8432)

http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQJZ200304012.htmStarting from nonlinear equations on the f-plane containing frictional dissipation under the Boussinesq approximation, a new kind of generalized energy is proposed as the Lyapunov function, and averages are taken as any functions of (x, z) instead of the commonly-used means of bilinear functions of (x, z), thereby resulting in a new criterion of generalized nonlinear symmetric stability. It shows that not only must the dissipative coefficient be greater than a certain critical value but the initial disturbance amplitude must be synchronously smaller than another marginal value as well. It follows that the latter imposes a crucial constraint on the former, thus leading to the fact that when the amplitude is bigger compared to another critical value, generalized nonlinear subcritical symmetrical instability may occur. The new criterion contributes greatly to the improvement of the previous results of its kind.

Ran L. K., L. Liu, N. Li, and Y. B. Qi, 2013: The analysis of the potential-divergence wave activity density and its application to typhoon precipitation. Chinese Journal of Geophysics, 56, 3285- 3301. (in Chinese)

Ran L. K., Y. B. Qi, and S. C. Hao, 2014: Analysis and forecasting of heavy rainfall case on 21 July 2012 with dynamical parameters. Chinese J. Atmos. Sci., 38, 83- 100. (in Chinese)

Schultz D. M., P. N. Schumacher, 1999: The use and misuse of conditional symmetric instability. Mon. Wea. Rev., 127, 2709- 2732.10.1175/1520-0493(1999)127<2709:TUAMOC>2.0.CO;2

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http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F236268991_The_Use_and_Misuse_of_Conditional_Symmetric_Instability

refpaperuri:(c4198cbcf3217b565ed4284ac82407c8)

http://www.researchgate.net/publication/236268991_The_Use_and_Misuse_of_Conditional_Symmetric_InstabilityA commonly employed explanation for single- and multiple-banded clouds and precipitation in the extratropics is slantwise convection due to the release of moist symmetric instability (MSI), of which one type is conditional symmetric instability (CSI). This article presents a review of CSI with the intent of synthesizing the results from previous observational, theoretical, and modeling studies. This review contends that CSI as a diagnostic tool to assess slantwise convection has been, and continues to be, misused and overused. Drawing parallels to an ingredients-based methodology for forecasting deep, moist convection that requires the simultaneous presence of instability, moisture, and lift, some of the misapplications of CSI can be clarified. Many of these pitfalls have been noted by earlier authors, but are, nevertheless, often understated, misinterpreted, or neglected by later researchers and forecasters. Topics include the evaluation of the potential for slantwise convection, the relationship between frontogenesis and MSI, the coexistence of moist gravitational instability and MSI, the nature of banding associated with slantwise convection, and the diagnosis of slantwise convection using mesoscale numerical models. The review concludes with suggested directions for future observational, theoretical, and diagnostic investigation.

Schultz D. M., J. A. Knox, 2007: Banded convection caused by frontogenesis in a conditionally, symmetrically, and inertially unstable environment. Mon. Wea. Rev., 135, 2095- 2110.10.1175/MWR3400.1

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http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F252408854_Banded_Convection_Caused_by_Frontogenesis_in_a_Conditionally_Symmetrically_and_Inertially_Unstable_Environment

refpaperuri:(e3911dea003d2f4884d1a04eb4ad5e8c)

http://www.researchgate.net/publication/252408854_Banded_Convection_Caused_by_Frontogenesis_in_a_Conditionally_Symmetrically_and_Inertially_Unstable_EnvironmentAbstract Several eastest-oriented bands of clouds and light rain formed on 20 July 2005 over eastern Montana and the Dakotas. The cloud bands were spaced about 150 km apart, and the most intense band was about 20 km wide and 300 km long, featuring areas of maximum radar reflectivity factor of about 50 dB Z . The cloud bands formed poleward of an area of lower-tropospheric frontogenesis, where air of modest convective available potential energy was being lifted. During initiation and maintenance of the bands, mesoscale regions of dry symmetric and inertial instability were present in the region of the bands, suggesting a possible mechanism for the banding. Interpretation of the extant instabilities in the region of the bands was sensitive to the methodology to assess the instability. The release of these instabilities produced circulations with enough vertical motion to lift parcels to their lifting condensation level, resulting in the observed cloud bands. A high-resolution, numerical weather prediction model demonstrated that forecasting these types of events in such real-time models is possible, although the timing, evolution, and spacing of the bands were not faithfully reproduced. This case is compared to two previous cases in the literature where banded convection was associated with a combination of conditional, symmetric, and inertial instability.

Seltzer M. A., R. E. Passarelli, and K. A. Emanuel, 1985: The possible role of symmetric instability in the formation of precipitation bands. J. Atmos. Sci., 42, 2207- 2219.10.1175/1520-0469(1985)042<2207:TPROSI>2.0.CO;2

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http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F253468676_The_Possible_Role_of_Symmetric_Instability_in_the_Formation_of_Precipitation_Bands

refpaperuri:(5232728ffdda787e2377c9bd701d76ca)

http://www.researchgate.net/publication/253468676_The_Possible_Role_of_Symmetric_Instability_in_the_Formation_of_Precipitation_BandsAbstract Fifteen cases of banded and nonbanded precipitation not associated with surface frontal regions are presented. Results from the linear perturbation and parcel theories of symmetric instability are compared to the observed properties of these bands. Symmetric instability can explain many of the features of the bands considered in this study: all of the bands are aligned parallel to the thermal wind; strong shear and near-neutral static stabilities are observed when bands occur; multiple bands have a wavelength that is related to the depth of the unstable region and the slope of moist isentropic surfaces. However, the linear theory of symmetric instability assumes a basic state of unidirectional flow and thermal wind balance, while the observations indicate that in some cases these conditions are not met. This study supports the hypothesis that symmetric instability may be responsible for precipitation bands, but the comparison between theory and observations is hampered by the inability of the pre...

Seman C. J., 1994: A numerical study of nonlinear nonhydrostatic conditional symmetric instability in a convectively unstable atmosphere. J. Atmos. Sci., 51, 1352- 1371.2169d519-10ef-4a0b-a6dd-e4618ec0ab04

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http%3A%2F%2Fconnection.ebscohost.com%2Fc%2Farticles%2F9501202770%2Fnumerical-study-nonlinear-nonhydrostatic-conditional-symmetric-instability-convectively

refpaperuri:(2463d0426c5908d3235b110a0e6636b6)

http://connection.ebscohost.com/c/articles/9501202770/numerical-study-nonlinear-nonhydrostatic-conditional-symmetric-instability-convectivelyStudies nonlinear hydrostatic conditional symmetric instability (CSI) as an initial value problem. Use of a two-dimensional, nonlinear, nohydrostatic mesoscale/cloud model; Simulation of the rotating baroclinic field (BCF); Enhancement of mesoscale circulation growth by baroclinicity.

Stone P. H., 1966: On non-geostrophic baroclinic stability. J. Atmos. Sci., 23, 390- 400.10.1175/1520-0469(1966)023<0390:ONGBS>2.0.CO;2

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http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F234236233_On_Non-Geostrophic_Baroclinic_Stability

refpaperuri:(a650a5c230442c57a61dea3fa72661a5)

http://www.researchgate.net/publication/234236233_On_Non-Geostrophic_Baroclinic_StabilityAbstract Eady's (1949) model is used to study the non-geostorphic baroclinic stability problem. Growth rates for various types of perturbations are found as a function of the Richardson number, Ri The results indicate that the conventional baroclinic instabilities dominate if Ri > 0.95; symmetric instabilities dominate if 1/4 Ri > 0.95; and symmetric instabilities dominate if Ri < 1/4. It is suggested that symmetric instabilities may play an important role in the dynamics of the atmospheres of the major planets of the solar system.

Stone P. H., 1970: On non-geostrophic baroclinic stability: Part II. J. Atmos. Sci., 27, 721- 726.10.1175/1520-0469(1970)0272.0.CO;2

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http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F253716804_On_Non-Geostrophic_Baroclinic_Stability_Part_II

refpaperuri:(5428cbf99955c01f244936f740873130)

http://www.researchgate.net/publication/253716804_On_Non-Geostrophic_Baroclinic_Stability_Part_IIAbstract The solutions of Eady's 1949 model of baroclinic stability are extended numerically to include the non-geostrophic perturbations which wore not covered by the analysis in Part I. It is found that the largest growth rates are never associated with these new perturbations, so the tentative conclusions of Part I are verified. The more exact numerical solutions lead only to slight quantitative modifications of the results of Part I. If we let Ri be the Richardson number, then the largest growth rates are associated with “geostrophic” baroclinic instability if Ri>0.950; with symmetric instability if 04<Ri<0.950; and with Kelvin-Helmholtz instability if 0<Ri<04. Geostrophic baroclinic instability and symmetric instability can exist simultaneously if 0.84<Ri<1, and symmetric instability and Kelvin-Helmholtz instability can exist simultaneously if 0<Ri<04

Stone P. H., 1971: Baroclinic stability under non-hydrostatic conditions. J. Fluid Mech., 45, 659- 671.

Sun J. S., N. He, R. Guo, and M. X. Chen, 2013a: The configuration change and train effect mechanism of multi-cell storms. Chinese J. Atmos. Sci., 37, 137- 148. (in Chinese)fe0bb921-635f-4fc9-8488-1390ae5af800

a08535cd253d9eda8ac8f07544d692cf

http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQXK201301014.htm

http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQXK201301014.htmSeveral multi-cell storm systems occurring in the Beijing area have been investigated by using the low-level thermal and dynamical retrieval system of four-dimensional variational assimilation (4Dvar) based on the Variational Doppler Radar Analysis System (VDRAS). This paper examines the physical mechanism of configuration processes, intensity changes, and train-effect phenomena that occur during the transmission of linear multi-cell storms. The following results are reported: (1) In a multi-cell storm system in which the transmission direction of the cells is constant with a convective band such as a squall line, the configuration changes such that linear reflectivity becomes arched, and intensity changes of the cells are related to interaction of cells transmitting process and environmental low-level air flow. If the frontal inflow is a warm and moist air stream, and stronger vapor convergence is present, the cell flourishes more easily and transmits faster; otherwise, the cell weakens and transmits slowly. Therefore, in squall-line system nowcasting, the intersection of the multi-cell transmitting direction and the environmental vapor convergent line should be closely followed because the cell will travel faster, and the most severe effects of convection will occur. (2) In a multi-cell system that shows characteristics of a train effect, the cell transmitting feature and developing environment differ almost completely from those of the multi-cell previously mentioned. Train-effect phenomena generally occur in low-level warm and moist air streams or neighboring low-level jets in unstable ambient atmospheric conditions. The transmitting mechanism of the storm cell can be connected with the propagation and stimulation of an inertial gravity wave such that the warm and moist air stream or low-level jet is a transmitting band for warm vapor advection. When inertial gravity wave propagates from high to lowse , the wave receives energy from the ambient atmosphere and develops constantly. Therefore, during storm cell transmission, cells gradually enhance and become arranged in a row to produce the torrential rain center in the leading end of the wave train.

Sun J. H., S. X. Zhao, S. M. Fu, H. J. Wang, and L. L. Zheng, 2013b: Multi-scale characteristics of record heavy rainfall over Beijing area on July 21, 2012. Chinese J. Atmos. Sci., 37, 705- 718. (in Chinese)f3144b5d-00c8-4d3a-9758-50549dd1370f

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http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-DQXK201303014.htm

refpaperuri:(a4de56f9134485b4ec693e7bbb61fc79)

http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQXK201303014.htmObservational and National Centers for Environmental Prediction (NCEP) analysis data are used to diagnose the characteristics of synoptic circulations, sources of water vapor, and mesoscale convective systems (MCS) related to the formation of heavy rainfall on July 21, 2012. Results indicate that the locations and intensities of upper-to lower-level synoptic circulations and mid-to low-latitude systems are favorable for the heavy rainfall formation over North China that occurred under typical weather patterns with high pressure to the east and low pressure to the west. Synoptic systems such as vortices, shear lines, troughs, cold fronts, and low-level jets affect the formation and intensity of heavy rainfall. Tropical cyclones in the Bay of Bengal and the western Pacific Ocean provide favorable conditions for the transportation of water vapor from the ocean to the mainland. The sources of water vapor to North China are the Bay of Bengal, the Bohai Sea, and the Yellow Sea. Water vapor in the lowertroposphere is mainly transported from the latter two sources, and water vapor in the middle troposphere is mainly transported from the former. The entire heavy rainfall process involves two stages. During the first stage, the trigger-ing of MCS is associated with cold air invasion, terrain, and easterly wind in the prefrontal area. During the second stage, the organization and intensification of MCS are forced by the cold front. Under favorable synoptic circulations, the frequent development of stable and persistent MCS is important for the formation of the heavy rainfall event ex- amined in this study.

Wang J. Y., C. G. Cui, X. F. Wang, and W. J. Cui, 2014: Analysis on water vapor transport and budget of the severe torrential rain over Beijing Region on 21 July 2012. Meteorological Monthly, 40, 133- 145. (in Chinese)bab86408-1d8c-414c-b672-d0d0de0f53ef

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http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTotal-QXXX201402001.htm

http://en.cnki.com.cn/Article_en/CJFDTotal-QXXX201402001.htmBy using the NCEP reanalysis data,the vapor budget of the area covered by the severe torrential rain over the northeast of North China on 21 July,2012 is calculated according to the vapor budget equation.The results show that meridional water vapor transportation is dominant while the extremely heavy rain hits Beijing Region,where most moist vapor comes from the southern boundary below 500 hPa.The low-level regional moisture convergence is consistent with the time and space when the torrential rain breaks out and develops.Above the middle level the vertical vapor transport is more prominent.Then the variation features of the vapor transport corridors and their moisture contributions are got through the HYSPLIT mode.The backward trajectory analyses illustrate two major vapor transport corridors.The moistest vapor derived from Yellow Sea and East China Sea along the low level make the main moisture contribution during the heavy precipitation.Moisture from the South China Sea and the Bay of Bengal strengthens the water vapor in the region when the heavy rain starts and develops.Also the drier vapor corridor along the high level from the northwest of China plays an important role in this case.

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

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refpaperuri:(30cd25d1f715e380ba4f8cdaf997c49b)

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 15 limitted due to the declination of moist isentropic surfaces,and atheory of slantwise vorticity development based on Z-coordinate and P-coordinate was then proposed. According to this theory,whether the atmosphere 15 moist symetrically stable or unstable,or convectively stable or unstable,50 long as the moist insentropic surface 15 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.Ina 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 15 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 MPVZ respectively,is effective for inaentifying 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. P. Cai, 1997: Vertical wind shear and down-sliding slantwise vorticity development. Scientia Atmospherica Sinica, 21, 273- 282. (in Chinese).a02ae177-78f8-4414-8b26-a17e8ef957ac

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

refpaperuri:(0508272d745c3c216b90db8661851796)

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) θ e/ p) and P m2 (=- g× / p· 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, 1-15. (in Chinese)05e7eeb5-e779-4c47-af41-c641ded38421

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

Xu Q., 1986: Conditional symmetric instability and mesoscale rainbands. Quart. J. Roy. Meteor. Soc., 112, 315- 334.10.1002/qj.49711247203

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.49711247203%2Fcitedby

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http://onlinelibrary.wiley.com/doi/10.1002/qj.49711247203/citedbyABSTRACT The linear theory of conditional symmetric instability (CSI) is re-examined in a rigorous framework. In comparison with symmetric instability a new feature of CSI is that the moist updraught tends to be narrow, as with conditional buoyancy instability (CBI). As the width of the moist updraught varies from its tolerance maximum to infinitesimal, the inviscid growth rate increases from zero to its maximum and the slope of the moist updraught increases from the absolute momentum surface to the moist most unstable surface. The fact that CSI circulations absorb energy from the basic shear and moist thermal field but lose energy to the dry basic thermal field is responsible for the narrow and slant feature of the moist updraught. When a bulk viscosity is accounted for, the most rapidly growing CSI modes bear a qualitative resemblance to some observed rainbands. The stability criterion of viscous CSI also shows a better comparison with observational data than inviscid CSI. The linear CSI theory here predicts that the isolated mode is preferred to other non-isolated (periodic or irregular spacing) modes. The preference of non-isolated modes is speculated to occur in the nonlinear stage.

Zhang K. S., 1988a: On mesoscale instability of a baroclinic flow 1. Symmetric instability. Acta Meteorologica Sinica, 46, 258- 266. (in Chinese)10.11676/qxxb1988.033

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http://en.cnki.com.cn/Article_en/CJFDTOTAL-QXXB198803001.htm

http://en.cnki.com.cn/Article_en/CJFDTOTAL-QXXB198803001.htmThe first part of the present work investigates instability of a baroclinic basic flow against the mesoscale disturbances parallel to it. The focus of this study is to search for the possibility for a mesoscale disturbance of band structure to occur in a stably stratified atmosphere and its effect on triggering and organizing deep convections,The two- and three-dimensional perturbation equations, suitable to solving eigenvalue problems by use of the generalized matrix method and shooting method, are formed under anelastic approximation. The criteria for symmetric instability to set in are discussed for a linear, a hyperbolic-tangential and a real wind profile sounded before occurrence of a squall line event in SESAME 1979. The effect of baroclinicity of the basic flow on occurrence of this kind inertial convection is also analyzed in terms of energetic calculation.

Zhang K. S., 1988b: On mesoscale instability of a baroclinic flow 2. transversal instability. Acta Meteorologica Sinica, 46, 385- 392. (in Chinese)10.11676/qxxb1988.050

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http%3A%2F%2Fen.cnki.com.cn%2Farticle_en%2Fcjfdtotal-qxxb198804000.htm

refpaperuri:(587a19634e5bb3343173431800e86dc5)

http://en.cnki.com.cn/article_en/cjfdtotal-qxxb198804000.htmThe second part of the present study investigates instability of a baroclinic basic flow against the transversal mesoscale disturbances. By generalizing the Eady model to an ageostrophic one, the bi-mode and even mufti-mode instability spectra may occur for a baroclinic basic flow. The Eady-mode appears at synoptic scales, whereas the ageostrophic, baroclinic mode appears at inertial scales ranging from sevenal tens to hundreds kinometers. The Eady-mode, with a qrasi-geostrophic structure, has a larger vertical depth, while the meso-modes are mostly confined to the middle and lower troposphere with an asymmetric "cat eyes" pattern in the vertical cross section and an alternative distribution of divergence and vorticity in the horizontal plane. The growth rate of the mesoscale mode is about four times larger than that of the Eady-mode for the same wind profile of linear distribution. the major energy source, which supports these two modes, is the baroclinic available potential energy stored in a rotating basic flow. The results of this paper may be useful in analysis of the mesoscale distur-bances'propagating along a basic flow.

Zhang L. F., M. Zhang, 1992: Wave-CISK and symmetric instability. Scientia Atmospherica Sinica, 16, 669- 676. (in Chinese)717634e8-e607-4f5c-94d1-e3861f0d48a2

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http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-DQXK199206003.htm

refpaperuri:(66c526c0c38ec8aa2833343e03afae3b)

http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQXK199206003.htmIn this paper the symmetric instability is studied when the condensation heating existing. The wave-CISK parameterized scheme is used in the convection condensation heating term. The calculation results show that the disturbance, of propagating symmetric instability is produced through CISK mechanism and the propagating direction, the growing rate and the structure of disturbance are affected by convection condensation heating.