Fundamental Aspects of Tropical Cyclone Dynamics. Part III: The Hurricane Engine's Turbobooster, or More Power to Hurricanes and Typhoons.

Michael Montgomery
Naval Postgraduate School

The maximum intensity that a hurricane can attain in a given atmospheric and oceanic environment is called
the maximum potential intensity, or potential intensity (PI) for short. Prior theoretical and observational work
on this topic has contributed much to understanding the thermo-mechanical processes governing the PI of
a hurricane vortex. Understanding the PI problem has both basic and applied scientific value. On the applied
side, for example, the PI places an important constraint on the magnitude of storm intensity for a particular
storm threatening a populated coastal region or for all storms globally in a climate warming scenario.
While prior theory is broadly supported by large-scale observations, we revisit this classical problem with a
suite of new high resolution numerical experiments and new high resolution in situ observations with
an aim to better understand the role of sub-vortex scale structures in the PI of a hurricane. Theoretical
modifications to incorporate pertinent small-scale phenomena are proposed and tested using an axisymmetric
numerical cloud model. The results point to the importance of a turbulent moist region within the low-level
eye that contributes significantly to the energetics of the eyewall and hence to the intensity of the hurricane.
Implications to reality are discussed.

My research on hurricane intensity began while working with a former masters student, J. P. Camp, and has continued
with my colleagues J. Persing (CSU), M. Bell (NCAR/NPS), S. Aberson, M. Black, P Black & F. Marks, Jr. (NOAA's
Hurricane Research Division, Miami, FL) and K. Emanuel (MIT).

Audio (MP3 File, Podcast Ready)

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