On the dynamics of mid-latitude synoptic systems with intense cumulus convection

Jocelyn Mailhot; Man Kong Yau

doi:10.3402/tellusa.v38i4.11723

On the dynamics of mid-latitude synoptic systems with intense cumulus convection

Tellus

Volume 38 (1986): Issue 4

By: Jocelyn Mailhot and Man Kong Yau

Open Access

|Jan 1986

Abstract

A scale analysis appropriate for mid-latitude explosive cyclones is presented, including the effects of cumulus clouds. First-order equations are derived for the thermodynamic and vorticity fields. It is shown that the quasi-geostrophic form of the divergence equation is a good approximation, while the geostrophic wind approximation is no longer valid in the presence of intense convection. It is also found that diabatic heating by clouds is responsible for the enhancement of the large-scale vertical motion which induces a divergent wind on the same order as the rotational part. Therefore, cumulus convection affects the large-scale flow through an induced secondary circulation, which manifests its effect in the thermodynamic and vorticity equations as the advection by the divergent wind component. In addition, cumulus clouds also affect the large-scale vorticity by imparting excess cloud vorticity to the environment.

Interactions between cloud and large scales are also discussed in terms of the omega and potential vorticity equations. It is shown that the dominant forcing terms, i.e. diabatic heating and vortex stretching due to cumulus clouds, tend to balance in the large-scale potential vorticity equation, and that the influence of cumulus convection appears through the smaller forcings due to cloud life-cycles and two non-geostrophic effects.

A three-level model is employed to investigate the effects of cumulus convection on baroclinic instability, with Ekman-CISK as the closure condition. It is found that the various forcing mechanisms produce quite different effects on the evolution and structure of the baroclinically unstable waves.

References

Arakawa , A. and Schubert , W. H. 1974 . Interaction of a cumulus cloud ensemble with the large-scale environment, Part I . J. Atmos. Sci . 31 , 674 – 701 .
Search in Google Scholar Back to article
Bosart , L. F. 1981 . The President's Day snowstorm of 18-19 February 1979: A subsynoptic scale event . Mon. Wea. Rev . 109 , 1542 – 1566 .
Search in Google Scholar Back to article
Charney , J. G. and Eliassen , A. 1964 . On the growth of the hurricane depression . J. Atmos. Sci . 21 , 68 – 75 .
Search in Google Scholar Back to article
Chen , T. C. , Alpert , J. C. and Schlatter , T. W. 1978 . The effects of divergent and nondivergent winds on the kinetic energy budget of a mid-latitude cyclone: A case study . Mon. Wea. Rev . 106 , 458 – 468 .
Search in Google Scholar Back to article
Cho , H. R. 1977 . Contribution of cumulus cloud life-cycle effects to the large-scale heat and moisture budget equations . J. Atmos. Sci . 34 , 87 – 97 .
Search in Google Scholar Back to article
Cho , H. R. , Cheng , L. and Bloxam , R. M. 1979 . The representation of cumulus cloud effects in the large-scale vorticity equation . J. Atmos. Sci . 36 , 127 – 139 .
Search in Google Scholar Back to article
Cho , H. R. and Cheng , L. 1980 . Parameterization of horizontal transport of vorticity by cumulus convection . J. Atmos. Sci . 37 , 812 – 826 .
Search in Google Scholar Back to article
Cho , H. R. and Clark , T. L. 1981 . A numerical investigation of the structure of vorticity fields associated with a deep convective cloud . Mon. Wea. Rev . 109 , 1654 – 1670 .
Search in Google Scholar Back to article
Danard , M. B. 1964 . On the influence of released latent heat on cyclone development . J. Appl. Meteorol . 3 , 27 – 37 .
Search in Google Scholar Back to article
Gyakum , J. R. 1983 . On the evolution of the QE II storm. II: Dynamic and thermodynamic aspects . Mon. Wea. Rev . 111 , 1156 – 1173 .
Search in Google Scholar Back to article
Haltiner , G. J. 1971 . Numerical weather prediction . Wiley , New York , 317 pp.
Search in Google Scholar Back to article
Holton , J. R. 1979 . An introduction to dynamic meteorology , 2nd edition . Academic Press , New York , 391 pp.
Search in Google Scholar Back to article
Krishnamurti , T. N. 1968 . A study of a developing wave cyclone . Mon. Wea. Rev . 96 , 208 – 217 .
Search in Google Scholar Back to article
Krishnamurti , T. N. and Moxim , W. J. 1971 . On parameterization of convective and non-convective latent heat release . J. Appl. Meteorol . 10 , 3 – 13 .
Search in Google Scholar Back to article
Kuo , H. L. 1965 . On formation and intensification of tropical cyclones through latent heat release by cumulus convection . J. Atmos. Sci . 22 , 40 – 63 .
Search in Google Scholar Back to article
Kuo , H. L. 1974 . Further studies of the parameterization of the influence of cumulus convection on large-scale flow . J. Atmos. Sci . 31 , 1232 – 1240 .
Search in Google Scholar Back to article
Mailhot , J. 1985 . On the effects of cumulus convection on mid-latitude explosive cyclones . McGill University Scientific Report MW- 96 , 204 pp.
Search in Google Scholar Back to article
Ooyama , K. 1971 . A theory of parameterization of cumulus convection . J. Meteorol. Soc. Japan 49 , 744 – 756 .
Search in Google Scholar Back to article
Palmen , E. 1958 . Vertical circulation and release of kinetic energy during the development of Hurricane Hazel into an extratropical storm . Tellus 10 , 1 – 23 .
Search in Google Scholar Back to article
Riehl , H. and Malkus , J. S. 1958 . On the heat balance of the equatorial trough zone . Geophysica 6 , 503 – 538 .
Search in Google Scholar Back to article
Sanders , F. and Gyakum , J. R. 1980 . Synoptic-dynamic climatology of the “bomb” . Mon. Wea. Rev . 108 , 1589 – 1606 .
Search in Google Scholar Back to article
Shapiro , L. J. 1978 . The vorticity budget of a composite African tropical wave disturbance . Mon. Wea. Rev . 106 , 806 – 817 .
Search in Google Scholar Back to article
Shapiro , L. J. and Stevens , D. E. 1980 . Parameterization of convective effects on the momentum and vorticity budgets of synoptic-scale Atlantic tropical waves . Mon. Wea. Rev . 108 , 1816 – 1826 .
Search in Google Scholar Back to article
Stevens , D. E. , Lindzen , R. S. and Shapiro , L. J. 1977 . A new model of tropical waves incorporating momentum mixing by cumulus convection . Dyn. Atmos. Oceans 1 , 365 – 425 .
Search in Google Scholar Back to article
Tracton , M. S. 1973 . The role of cumulus convection in the development of extratropical cyclones . Mon. Wea. Rev . 101 , 573 – 593 .
Search in Google Scholar Back to article
Vincent , D. G. and Schlatter , T. W. 1979 . Evidence of deep convection as a source of synoptic scale kinetic energy . Tellus 31 , 493 – 504 .
Search in Google Scholar Back to article
Yanai , M. , Esbensen , S. and Chu , J. H. 1973 . Determination of bulk properties of tropical cloud clusters from large-scale heat and moisture budgets . J. Atmos. Sci . 30 , 611 – 627 .
Search in Google Scholar Back to article
Yip , T. C. and Cho , H. R. 1982 . Dynamics of quasi-geostrophic systems with cumulus convection . Tellus 34 , 63 – 73 .
Search in Google Scholar Back to article

Articles in this issue

DOI: https://doi.org/10.3402/tellusa.v38i4.11723 | Journal eISSN: 3035-9554

Journal RSS Feed

Language: English

Page range: 366 - 377

Submitted on: Mar 12, 1985

Accepted on: Nov 29, 1985

Published on: Jan 1, 1986

Published by: Stockholm University Press

In partnership with: Paradigm Publishing Services

© 1986 Jocelyn Mailhot, Man Kong Yau, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 38 (1986): Issue 4