Editorial Type:
Article
Article Type:
Research Article

Influence of Atmospheric Asymmetries on the Intensification of Hurricane Opal: Piecewise PV Inversion Diagnosis of a GFDL Model Forecast

Lloyd J. Shapiro Meteorological Institute, Ludwig-Maximilians-University, Munich, Germany

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J. Dominique Möller Meteorological Institute, Ludwig-Maximilians-University, Munich, Germany

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Print Publication:
01 Aug 2003
DOI:
https://doi.org/10.1175//2552.1
Page(s):
1637–1649
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Abstract

Although Hurricane Opal of 1995 is one of the most intensely studied hurricanes ever, the cause of the hurricane's rapid intensification over the Gulf of Mexico is still a matter of controversy. While some authors have concluded that an approaching upper-level atmospheric trough had a significant impact on intensification, others have inferred only a small impact of the trough on the hurricane's strengthening. A recent study by the present authors diagnosed a Geophysical Fluid Dynamics Laboratory (GFDL) model forecast and found that eddy fluxes made only a small contribution to the lower-tropospheric evolution of the model hurricane vortex near the core. Thus, at face value, this previous study supported the conclusion that the upper-level trough was not important to the intensification of Opal. As noted in that study, however, in order to isolate the contribution of the trough by itself, the technique of piecewise potential vorticity (PV) inversion is required. The present study is the first to use this method in a diagnostic framework to determine the asymmetric features that contribute to tropical cyclone intensification.

The present study uses the same GFDL hurricane model forecast as in the previous study to diagnose the balanced contribution of various pieces of the asymmetric PV anomaly to the intensification of the model Opal vortex. Though the upper-level trough is an outer-environmental feature, its influence is found to extend into Opal's inner-core region. The eddies associated with the trough induce an upper-level inner-core acceleration. An estimate of the impact of convective feedback on the influence of the upper-level trough on Opal's evolution is made. The results elucidate and modify the conclusions of other authors. There is no indication from the present diagnosis that the upper-level trough was a significant contributor to Opal's lower-tropospheric intensification.

Corresponding author address: Dr. Lloyd J. Shapiro, Meteorological Institute, Ludwig-Maximilians-University, Theresienstr. 37, 80333 Munich, Germany. Email: shapiro@meteo.physik.uni-muenchen.de

Abstract

Although Hurricane Opal of 1995 is one of the most intensely studied hurricanes ever, the cause of the hurricane's rapid intensification over the Gulf of Mexico is still a matter of controversy. While some authors have concluded that an approaching upper-level atmospheric trough had a significant impact on intensification, others have inferred only a small impact of the trough on the hurricane's strengthening. A recent study by the present authors diagnosed a Geophysical Fluid Dynamics Laboratory (GFDL) model forecast and found that eddy fluxes made only a small contribution to the lower-tropospheric evolution of the model hurricane vortex near the core. Thus, at face value, this previous study supported the conclusion that the upper-level trough was not important to the intensification of Opal. As noted in that study, however, in order to isolate the contribution of the trough by itself, the technique of piecewise potential vorticity (PV) inversion is required. The present study is the first to use this method in a diagnostic framework to determine the asymmetric features that contribute to tropical cyclone intensification.

The present study uses the same GFDL hurricane model forecast as in the previous study to diagnose the balanced contribution of various pieces of the asymmetric PV anomaly to the intensification of the model Opal vortex. Though the upper-level trough is an outer-environmental feature, its influence is found to extend into Opal's inner-core region. The eddies associated with the trough induce an upper-level inner-core acceleration. An estimate of the impact of convective feedback on the influence of the upper-level trough on Opal's evolution is made. The results elucidate and modify the conclusions of other authors. There is no indication from the present diagnosis that the upper-level trough was a significant contributor to Opal's lower-tropospheric intensification.

Corresponding author address: Dr. Lloyd J. Shapiro, Meteorological Institute, Ludwig-Maximilians-University, Theresienstr. 37, 80333 Munich, Germany. Email: shapiro@meteo.physik.uni-muenchen.de

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  • Bosart, L. F., C. S. Veldon, W. E. Bracken, J. Molinari, and P. G. Black, 2000: Environmental influences on the rapid intensification of Hurricane Opal (1995) over the Gulf of Mexico. Mon. Wea. Rev., 128 , 322–352.

    • Search Google Scholar
    • Export Citation

  • Davis, C. A., 1992: Piecewise potential vorticty inversion. J. Atmos. Sci., 49 , 1397–1411.

  • Davis, C. A., and K. A. Emanuel, 1991: Potential vorticity diagnostics of cyclogenesis. Mon. Wea. Rev., 119 , 1929–1953.

  • Durran, D. R., and J. B. Klemp, 1982: On the effects of moisture on the Brunt–Väisälä frequency. J. Atmos. Sci., 39 , 2152–2158.

  • Eliassen, A., 1952: Slow thermally or frictionally controlled meridional circulation in a circular vortex. Astrophys. Norv., 5 , 19–60.

    • Search Google Scholar
    • Export Citation

  • Emanuel, K. A., 1999: Thermodynamic control of hurricane intensity. Nature, 401 , 665–669.

  • Holland, G. J., and R. T. Merrill, 1984: On the dynamics of tropical cyclone structural changes. Quart. J. Roy. Meteor. Soc., 110 , 723–745.

    • Search Google Scholar
    • Export Citation

  • Hong, X., S. W. Chang, S. Raman, L. K. Shay, and R. Hodur, 2000: The interaction between Hurricane Opal (1995) and a warm core ring in the Gulf of Mexico. Mon. Wea. Rev., 128 , 1347–1365.

    • Search Google Scholar
    • Export Citation

  • Hoskins, B. J., and F. P. Bretherton, 1972: Atmospheric frontogenesis models: Mathematical formulation and solution. J. Atmos. Sci., 29 , 11–37.

    • Search Google Scholar
    • Export Citation

  • Kurihara, Y., R. E. Tuleya, and M. A. Bender, 1998: The GFDL hurricane prediction system and its performance in the 1995 hurricane season. Mon. Wea. Rev., 126 , 1306–1322.

    • Search Google Scholar
    • Export Citation

  • McTaggart-Cowan, R., J. R. Gyakum, and M. K. Yau, 2001: Sensitivity testing of extratropical transition using potential vorticity inversion to modify initial conditions: Hurricane Earl case study. Mon. Wea. Rev., 129 , 1617–1636.

    • Search Google Scholar
    • Export Citation

  • Molinari, J., and D. Vollaro, 1989: External influences on hurricane intensity. Part I: Outflow layer eddy angular momentum fluxes. J. Atmos. Sci., 46 , 1093–1105.

    • Search Google Scholar
    • Export Citation

  • Möller, J. D., and L. J. Shapiro, 2002a: Balanced contributions to the intensification of Hurricane Opal as diagnosed from a GFDL model forecast. Mon. Wea. Rev., 130 , 1866–1881.

    • Search Google Scholar
    • Export Citation

  • Möller, J. D., and L. J. Shapiro, 2002b: Symmetric and asymmetric contributions to the intensification of Hurricane Opal in a GFDL model forecast. Preprints, 25th Conf. on Hurricanes and Tropical Meteorology, San Diego, CA, Amer. Meteor. Soc., 249–250.

    • Search Google Scholar
    • Export Citation

  • Montgomery, M. T., and B. Farrell, 1993: Tropical cyclone formation. J. Atmos. Sci., 50 , 285–310.

  • Persing, J., M. T. Montgomery, and R. E. Tuleya, 2002: Environmental interactions in the GFDL hurricane model for Hurricane Opal. Mon. Wea. Rev., 130 , 298–317.

    • Search Google Scholar
    • Export Citation

  • Shapiro, L. J., 1996: The motion of Hurricane Gloria: A potential vorticity diagnosis. Mon. Wea. Rev., 124 , 2497–2508.

  • Shapiro, L. J., and M. T. Montgomery, 1993: A three-dimensional balance theory for rapidly rotating vortices. J. Atmos. Sci., 50 , 3322–3335.

    • Search Google Scholar
    • Export Citation

  • Shapiro, L. J., and J. L. Franklin, 1999: Potential vorticity asymmetries and tropical cyclone motion. Mon. Wea. Rev., 127 , 124–131.

  • Shay, L. K., G. J. Goni, and P. G. Black, 2000: Effects of a warm oceanic feature on Hurricane Opal. Mon. Wea. Rev., 128 , 1366–1383.

  • Wu, C-C., and K. A. Emanuel, 1995a: Potential vorticity diagnosis of hurricane movement. Part I: A case study of Hurricane Bob (1991). Mon. Wea. Rev., 123 , 69–92.

    • Search Google Scholar
    • Export Citation

  • Wu, C-C., and K. A. Emanuel, 1995b: Potential vorticity diagnosis of hurricane movement. Part II: Tropical Storm Ana (1991) and Hurricane Andrew (1992). Mon. Wea. Rev., 123 , 93–109.

    • Search Google Scholar
    • Export Citation
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