The SAB strongly
influences the meteorology of the eastern seaboard. The paths of winter
cyclones that impact the U.S. east coast cross the region. Also, many
tropical storms and hurricanes pass through this area in summer and fall.
As these systems come close to the eastern seaboard, predictions of storm
development and landfall become critically important. Both types of storm
systems derive their energy from the air- sea gradients in heat and humidity.
The middle and outer shelf areas are relatively warm due to the proximity
of the Gulf Stream and provide an important energy source for both of
these systems. Present studies of these processes rely on extremely sparse
coverage provided by ocean buoys and coastal stations. Since continuous
mesoscale atmospheric observations from stable platforms near a large
thermal sea gradient are rare, the tower platforms provide a unique opportunity
to advance our understanding of how weather systems and the coastal ocean
interact.
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Tropical Cyclones Passing Within
50 and 100 nautical miles of R2 Tower
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Six-minute
average wind speed, air pressure, and significant wave height at tower
R2 during the passage of Hurricane Irene in October 1999.Peak sustained
winds exceeded 25 m/s, and peak wave heights reached 4.5 m.

Since
July 1999, more than a dozen extreme wind events have been observed at
50 m height on R2 during the passage of squall lines. 6-minute averaged
wind speeds of 40-60 m/s were associated with a rapid decrease in air
temperature, high frequency fluctuations in barometric pressure, and downpours
(April and Sept. squall line figures). A series of wind maxima at 50 m
ht. (but not at 10 m ht.) usually occurred during such events. The R2
observations are consistent with "downburst" events (Fujita, 1985). On
the Georgia shelf, this mechanism may transport continental air from aloft
to the sea surface.
Oceanic
heat budgets are important for understanding the Earth's climate and variability.
The ocean absorbs solar radiation and stores heat in the upper layers,
changes in heat storage result from local imbalances between heat input
and output through the sea surface. The sum of the changes in heat fluxes
into or out of a volume of water is the heat budget. The major terms of
the heat budget include insolation (Qsw), back radiation (Qlw), sensible
heat flux (Qsen) and latent heat flux (Qlat). The net heat flux (Qnet)
is the sum of these terms. Shown in the figure below, a temperature prediction
was made based on a simple mixed layer model, assuming that the net flux
affects the entire water column.
Over the winter
months the predicted temperature was a good estimate of observed ocean
temperature, and departures from the prediction show a correlation with
salinity variations. Since April 2000 the predicted temperature using
observations from the primary meteorological package 50 m above the water
is systematically lower than the observed temperatures. Replacing the
air temperature and humidity readings with those from the secondary package
10 m above the water surface yields a better prediction. This method is
preferable since the existing bulk formula cannot account for stratification
in the marine boundary layer.
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