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  • Bender, C. M., and S. A. Orszag, 1978: Asymptotic expansion of integrals. Advanced Mathematics for Scientists and Engineers, R. Ciofalo, Ed., McGraw-Hill, 247–316.

  • Bretherton, C., 1988: Group velocity and the linear response of stratified fluids to internal heat or mass sources. J. Atmos. Sci.,45, 81–93.

  • Garner, S. T., 1986: An orographic mechanism for rapid frontogenesis. Ph.D. dissertation, Massachusetts Institute of Technology, 222 pp. [Available from MIT, 77 Massachusetts Ave., Cambridge, MA 02139-4307.].

  • ——, 1995: Permanent and transient upstream effects in nonlinear stratified flow over a ridge. J. Atmos. Sci.,52, 227–246.

  • ——, 1999: Blocking and frontogenesis by two-dimensional terrain in baroclinic flow. Part I: Numerical experiments. J. Atmos. Sci.,56, 1495–1508.

  • Ley, B. E., and W. R. Peltier, 1978: Wave generation through frontal collapse. J. Atmos. Sci.,35, 3–17.

  • Lighthill, M. J., 1952: On sound generated aerodynamically. I. General theory. Proc. Roy. Soc. London,211A, 564–587.

  • Lilly, D. K., and J. B. Klemp, 1977: The effects of terrain shape on nonlinear hydrostatic mountain waves. J. Fluid Mech.,95, 241–261.

  • Long, R. R., 1953: Some aspects of the flow of stratified fluids, I. A theoretical investigation. Tellus,5, 42–48.

  • McIntyre, M. E., 1972: On Long’s hypothesis of no upstream influence in uniformly stratified or rotating flow. J. Fluid Mech.,52, 209–243.

  • Pierrehumbert, R. T., 1984: Linear results on the barrier effect of mesoscale mountains. J. Atmos. Sci.,41, 1356–1367.

  • ——, 1985: Stratified semi-geostrophic flow over two-dimensional topography in an unbounded atmosphere. J. Atmos. Sci.,42, 523–526.

  • ——, and B. Wyman, 1985: Upstream effects of mesoscale mountains. J. Atmos. Sci.,42, 977–1003.

  • Queney, P., 1947: Theory of perturbations in stratified currents with application to airflow over mountain barriers. Misc. Rep. 23, Dept. of Meteorology, University of Chicago, 67 pp. [Available from University of Chicago, 5801 South Ellis, Chicago, IL 60637.].

  • Segur, H., 1973: The Korteweg–de Vries equation and water waves. Solutions of the equation. Part 1. J. Fluid Mech.,59, 721–736.

  • Smith, R. B., 1977: The steepening of hydrostatic mountain waves. J. Atmos. Sci.,34, 1634–1654.

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Editorial Type:
Article
Article Type:
Research Article

Blocking and Frontogenesis by Two-Dimensional Terrain in Baroclinic Flow. Part II: Analysis of Flow Stagnation Mechanisms

Stephen T. Garner1
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  • 1 NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey
Print Publication:
01 Jun 1999
DOI:
https://doi.org/10.1175/1520-0469(1999)056<1509:BAFBTD>2.0.CO;2
Page(s):
1509–1523
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Abstract

Numerical solutions presented in a companion paper show that two-dimensional mesoscale terrain becomes a much stronger barrier to a continuously stratified flow when the flow contains warm advection. Here it is shown that this baroclinic enhancement is a strictly nonlinear phenomenon. The linear analysis indicates a weakening of the upstream response in warm advection. However, a weakly nonlinear analysis shows that baroclinicity facilitates blocking in warm advection by strengthening the nonlinearity in the cross-mountain momentum equation in such a way as to amplify the vertical shear on the windward flank of the ridge. This is enough to send the flow past the blocking threshold even when conditions over the mountain are too linear to produce wave breaking. A more intuitive mechanism whereby the upstream static stability is increased by the nonlinearity in the temperature equation is found to be much less important.

Corresponding author address: Dr. Stephen T. Garner, NOAA/GFDL, Princeton University, P.O. Box 308, Princeton, NJ 08542.

Email: stg@gfdl.gov

Abstract

Numerical solutions presented in a companion paper show that two-dimensional mesoscale terrain becomes a much stronger barrier to a continuously stratified flow when the flow contains warm advection. Here it is shown that this baroclinic enhancement is a strictly nonlinear phenomenon. The linear analysis indicates a weakening of the upstream response in warm advection. However, a weakly nonlinear analysis shows that baroclinicity facilitates blocking in warm advection by strengthening the nonlinearity in the cross-mountain momentum equation in such a way as to amplify the vertical shear on the windward flank of the ridge. This is enough to send the flow past the blocking threshold even when conditions over the mountain are too linear to produce wave breaking. A more intuitive mechanism whereby the upstream static stability is increased by the nonlinearity in the temperature equation is found to be much less important.

Corresponding author address: Dr. Stephen T. Garner, NOAA/GFDL, Princeton University, P.O. Box 308, Princeton, NJ 08542.

Email: stg@gfdl.gov

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