Thursday, 25 May 2000: 9:29 AM
The role of land surface water in retarding landfall decay and maintaining
landfalling hurricanes was little investigated and
suspected to be not significant because of the evaporation-induced
land surface cooling which leads to hurricane decoupling with its
underlying land surface. This study, using the
Geophysical Fluid Dynamics Laboratory/NOAA hurricane model,
investigated the landfalling hurricane-land
surface water interactions focusing on the
local land surface temperature cooling, surface flux reduction,
and their impacts on hurricane structure and intensity.
Different water depth and surface roughness conditions
were incorporated in the experiments starting with a Fran96-like
bogus embedded in an uniform easterly mean flow of 5m/s.
Results showed that surface evaporation is the primary cause
of the major local surface cooling during night while the cloud effects
on solar radiation enhance the local surface cooling around the core
during the day.
A layer of half meter water noticeably retards landfall decay and retains
a hurricane of a certain intensity. This makes the case significantly
different from both the ocean case with a large intensity reduction
and the dry land surface case in which landfalling hurricane finally
diminishes off.
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