Meteorology and Atmospheric Physics

, Volume 44, Issue 1–4, pp 101–117 | Cite as

Some dynamical properties of idealized thermally-forced meridional circulations in the tropics

  • J. J. Hack
  • W. H. Schubert
Article

Summary

Through the use of a zonal balance model we investigate the properties of the tropical meridional circulation to a range of specified diabatic forcing fields for climatologically observed zonal winds. As in earlier studies, the solutions show that latent heat release away from the equator forces an asymmetric meridional circulation in response the anisotropy in the inertial stability parameter with respect to the meridional location of the forcing. The presence of strong zonal flows appears to play a relatively minor role in determining the magnitude and asymmetry of the meridional circulation, whereas the structure of the diabatic heating, particularly the meridional breadth, proves to be of much greater importance.

A dynamic efficiency factor, which provides an analytic measure of the efficacy of diabatic heating at generating zonal kinetic energy, generally exhibits a meridionally symmetric structure except during Northern Hemisphere summer. This asymmetry gives rise to a pronounced sensitivity of zonal kinetic energy generation to the meridional location of ITCZ convection. Further examination of the flow pattern suggests that for zonal flows representative of those over the Indian Ocean during the Northern Hemisphere summer months, meridional displacements of the heating of less than 20° latitude can result in as much as an order of magnitude difference in the rate of kinetic energy generation. Solution of the balance system also implies the existence of a feedback mechanism, between zonally-organized convection and the energetics properties of the large-scale flow, that is highly sensitive to the meridional location of the convection.

Keywords

Heat Release Zonal Wind Zonal Flow Meridional Circulation Diabatic Heating 

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References

  1. Charney, J. G., Stern, M. E., 1962: On the stability of internal baroclinic jets in a rotating atmosphere.J. Atmos. Sci.,19, 159–172.Google Scholar
  2. Eliassen, A., 1983: The Charney-Stern theorem on barotropic-baroclinic instability.Pure Appl. Geophys.,121, 563–572.Google Scholar
  3. Ferrel, W., 1856: An essay on the winds and the currents of the ocean.Nashville J. Medicine and Surgery,11, 287–301.Google Scholar
  4. Findlater, J., 1969: A major low-level air current near the Indian Ocean during the northern summer.Quart. J. Roy. Meteor. Soc.,95, 362–380.Google Scholar
  5. Hack, J. J., Schubert, W. H., Stevens, D. E., Kuo, H.-C., 1989: Response of the Hadley circulation to convective forcing in the ITCZ.J. Atmos. Sci.,46, 2957–2973.Google Scholar
  6. Hadley, G., 1735: Concerning the cause of the general trade-winds.Phil. Trans.,29, 58–62.Google Scholar
  7. Halley, E., 1686: An historical account of the trade-winds and monsoons observable in the seas between and near the tropicks with an attempt to assign the physical cause of said winds.Phil. Trans.,26, 153–168.Google Scholar
  8. Held, I. M., Hou, A. Y., 1980: Nonlinear axially symmetric circulations in a nearly inviscid atmosphere.J. Atmos. Sci.,37, 515–533.Google Scholar
  9. Hoskins, B. J., Bretherton, F. P., 1972: Atmospheric frontogenesis models: mathematical formulation and solution.J. Atmos. Sci.,29, 11–37.Google Scholar
  10. Kornfield, J., Hasler, A. F., Hanson, K. J., Suomi, V. E., 1967: Photographic cloud climatology from ESSA III and V computer-produced mosaics.Bull. Amer. Meteor. Soc.,48, 878–882.Google Scholar
  11. Krishnamurti, T. N., Ardanuy, P., Ramanathan, Y., Pasch, R., 1981: On the onset vortex of the summer monsoons.Mon. Wea. Rev.,109, 344–363.Google Scholar
  12. Krishnamurti, T. N., Ramanathan, Y., 1982: Sensitivity of the monsoon onset to differential heating.J. Atmos. Sci.,39, 1290–1306.Google Scholar
  13. Krishnamurti, T. N., 1985: Summer Monsoon Experiment — A Review.Mon. Wea. Rev.,113, 1590–1626.Google Scholar
  14. Lindzen, R. S., Hou, A. Y., 1989: Hadley circulations for zonally averaged heating centered off the equator.J. Atmos. Sci.,45, 2416–2427.Google Scholar
  15. Lorenz, E. N., 1967: The nature and theory of the general circulation of the atmosphere. WMO/TD-218, 161 pp.Google Scholar
  16. Miller, D. B., Feddes, R. G., 1971: Global atlas of relative cloud over 1967–1970. Joint production by U.S. Department of Commerce and U.S. Air Force, Washington D.C. (Available from NTIS, Springfield, Va., AD 739434.)Google Scholar
  17. Murakami, T., Godbole, R. V., Kelkar, R. R., 1970: Numerical simulation of the monsoon along 80° E. Proc. of the Conference on the Summer Monsoon of Southeast Asia (Ramage, C. S., ed.). Navy Weather Research Facility, Norfolk, VA, pp. 39–51.Google Scholar
  18. Newell, R. E., Kidson, J. W., Vincent, D. G., Boer, G. J., 1972:The General Circulation of the Tropical Atmosphere and Interactions with Extratropical Latitudes, Vol. I. MIT Press, 258 pp.Google Scholar
  19. Oort, A. H., 1983: Global Atmospheric Circulation Statistics, 1958–1973. NOAA Professional Paper 14. U.S. Government Printing Office, 180 pp.Google Scholar
  20. Oort, A. H., Rasmusson, E. M., 1970: On the annual variation of the monthly mean meridional circulation.Mon. Wea. Rev.,98, 423–442.Google Scholar
  21. Schneider, E. K., 1977: Axially symmetric steady state models of the basic state for instability and climate studies. Part II. Nonlinear calculations.J. Atmos. Sci.,34, 280–296.Google Scholar
  22. Schneider, E. K., Lindzen, R. S., 1977: Axially symmetric steady state models of the basic state for instability and climate studies. Part I. Linear calculations.J. Atmos. Sci.,34, 253–279.Google Scholar
  23. Schubert, W. H., Alworth, B. T., 1987: Evolution of potential vorticity in tropical cyclones.Quart. J. Roy. Meteor. Soc.,113, 147–162.Google Scholar
  24. Schubert, W. H., Fulton, S. R., Hertenstein, R. F. A., 1989: Balanced atmospheric response to squall lines.J. Atmos. Sci.,46, 2478–2483.Google Scholar
  25. Trenberth, K. E., Olson, J. G., 1988: ECMWF global analyses 1979–1986: Circulation statistics and data evaluation, NCAR Tech. Note NCAR/TN-300+STR, National Center for Atmospheric Research, Boulder, Colo., NTIS PB 88-178165/AS, 12 fiche, 94 pp.Google Scholar
  26. Yanai, M., Esbensen, S., 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.Google Scholar

Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • J. J. Hack
    • 1
  • W. H. Schubert
    • 2
  1. 1.National Center for Atmospheric ResearchBoulderUSA
  2. 2.Colorado State UniversityFort CollinsUSA

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