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Subject : C1) Doesn't the low pressure in the
tropical cyclone center cause the storm surge?
Contributed by Chris Landsea
No. Many people assume that the partial vacuum at the
center of a tropical cyclone allows the ocean to rise up in
response, thus causing the destructive storm surges as the
cyclone makes landfall. However, this effect would be, for
example, with a 900 mb central pressure tropical cyclone, only 1
m (3 ft). The total storm surge for a tropical cyclone of this
intensity can be from 6 to 10 m (19 to 33 ft), or more. Most
(>85%) of the storm surge is caused by winds pushing the ocean surface
ahead of the storm on the right side of the track (left side of
the track in the Southern Hemisphere).
Since the surface pressure gradient (from the tropical
cyclone center to the environmental conditions) determines the
wind strength, the central pressure indirectly does indicate the
height of the storm surge, but not directly. Note also that
individual storm surges are dependent upon the coastal
topography, angle of incidence of landfall, speed of tropical
cyclone motion as well as the wind strength.
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