Upper ocean heat budget in the Gulf
Stream Extension in two high resolution models and the
influence of the Gulf Stream on Storm evolution - by
LuAnne Thompson
Our research groups work on western boundary current interactions
with the atmosphere is proceeding along two lines. In the first, we
are examining the heat budget in two high resolution ocean models of
the North Atlantic. One simulations consists of a hindcast of a one
tenth of a degree POP simulation of the North Atlantic performed by
Julie McClean from 1980 to the present. While the interannual variability
of the Gulf Stream in the Extension and Recirculation, we hope to use
the simulations to examine the relationships between heat and volume
transport and the structure of the circulation and whether some components
of the circulation are predictable from forcing fields. The second simulation
is a one third of a degree assimilative simulation of the North Atlantic
performed by MERCATOR in France that covers the altimetric observational
period. While the model is not eddy resolving, it does reproduce the
observed sea surface height fields owing to the assimilations, and it
is possible to examine the heat and volume transport relationships in
a more direct way.
The second aspect of our research involves the investigation
of how the state of the Gulf Stream influences cyclogenesis in the atmosphere
over head. While the state of upper level baroclinicity is important
for the strength and path of storms in the North Atlantic, our hypothesis
is that the position, strength and heat content of the Gulf Stream can
also be important under certain conditions. To examine this hypothesis,
we will be perform regional atmospheric simulations of storm evolution
over the Gulf Stream Extension. Our plan is to identify several storms
that evolve in the viscinity of the Gulf Stream by working closely with
the data analysis team led by Kathie Kelly. We will then simulate the
storm evolution using WRF (Weather Research and Forcasting Model) using
boundary conditions from numerical weather prediction models (NCEP or
ECMWF) while changing the surface temperature conditions to represent
different Gulf Stream states. The goal will be to determine under what
conditions, both atmospheric and oceanographic, the Gulf Stream can
significantly impact the evolution of storms, and whether from this
analysis, we can determine whether the Gulf Stream can have a long term
impact on the atmosphere outside of the planetary boundary layer.
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