Why do model tropical cyclones grow progressively in size and decay in intensity after reaching maturity?
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Authors
Kilroy, Gerard
Smith, Roger K.
Montgomery, Michael T.
Subjects
Tropical cyclones
Hurricanes
Typhoons
Boundary layer
Coriolis effect
Inertial stability
Intensity
Rotating convection paradigm
Hurricanes
Typhoons
Boundary layer
Coriolis effect
Inertial stability
Intensity
Rotating convection paradigm
Advisors
Date of Issue
2015
Date
Publisher
Meteorological Institute, Ludwig Maximilians University of Munich
Language
Abstract
The long term behaviour of tropical cyclones in the prototype problem for cyclone intensification
on an f -plane is examined using a nonhydrostatic, three-dimensional, numerical model. After reaching a mature intensity, the model storms progressively decay while both the inner core size, characterized by the radius of the eyewall, and size of the outer circulation, measured for example by the radius of gale force winds, progressively increase. This behaviour is explained in terms of a boundary-layer control mechanism in which the expansion of the swirling wind in the lower troposphere leads through boundary-layer dynamics to an increase in the radii of forced eyewall ascent as well as to a reduction in the
maximum tangential wind speed in the layer. These changes are accompanied by changes in the radial
and vertical distribution of diabatic heating. As long as the aggregate effects of inner-core
convection, characterized by the distribution of diabatic heating are able to draw absolute angular
momentum surfaces inwards, the outer circulation will continue to expand. The quantitative effects
of latitude on the foregoing processes are investigated also. The study provides new insight on the factors controlling the evolution of size and intensity of a tropical cyclone. It provides also a plausible, and arguably simpler, explanation for the expansion of the inner-core of Hurricane Isabel (2003) than that given previously.
Type
Article
Description
Series/Report No
Department
Meteorology
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
German Research Council
National Science Foundation
NASA
Naval Postgraduate School
NOAA
National Science Foundation
NASA
Naval Postgraduate School
NOAA
Funder
Grant no. SM30-23 (GRC)
Grant no. N62909-15-1-N021 (NSF)
AGS-1313948 (NSF)
HFIP Grant no. N0017315WR00048 (NOAA)
NNG11PK021 (NASA)
Grant no. N62909-15-1-N021 (NSF)
AGS-1313948 (NSF)
HFIP Grant no. N0017315WR00048 (NOAA)
NNG11PK021 (NASA)
Format
16 p.
Citation
G. Kilroy, R.K. Smith, M.T. Montgomery, "Why do model tropical storms grow progressively in size and decay in intensity after reaching maturity?", Tropical Cyclone Research Report, TCRR 2, (2015) pp. 1-16.
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.