Space Grant Consortium - University of Wisconsin - Green Bay

Realizing a Better Hydrostatic Response in NWP with MODIS Products
Jordan J. Gerth
Department of Atmospheric and Oceanic Sciences
University of Wisconsin – Madison
Madison, Wisconsin
ABSTRACT
Hydrostatic processes initiated along shorelines (herein, lake breezes) have been a neglected area
of study over the recent decade as the power and functionality of numerical weather prediction
(NWP) models has significantly grown. The Great Lakes have a substantial impact on life and
commerce in the large industrial cities on its coast. One particularly unique manifestation of the
lake breeze is the pneumonia front, which is a boundary containing a sharp temperature contrast
that occasions eastern Wisconsin during the spring and summer months. This paper provides a
review of important Great Lakes studies to date and examines how a coupling of spatially highresolution
data from weather satellites and the Weather Research and Forecast (WRF) model can
produce better forecasts through the enhancement of mesoscale and synoptic scale features in
marine-modified climates across the Great Lakes.
Introduction
Sea breezes, complex hydrostatic processes resulting from differential skin surface heating
between land and water, are sub-synoptic meteorological phenomena that significantly influence
the weather of coastal communities. The study of sea breezes in tropical climates, such as those
along the Florida peninsula, is ongoing (LaCasse 2008). While the behavior of sea breezes
occurring within mid-latitude maritime climates compared to those rooted in tropical maritime
climates is similar, and the dynamical and physical factors behind the genesis of each is
identical, there are some particular local aspects and manifestations of the former which are
worthy of study. The lesser studied category of sea breezes, lake breezes, are a relatively
common occurrence on the Great Lakes and other large, non-oceanic bodies of water in the midlatitudes
during the spring, summer, and fall months, but recent research on them is lacking.
The Great Lakes collectively form one of the largest reservoirs for fresh water in the world.
There are numerous large metropolitan areas with significant industry harboring on the Great
Lakes, including: Green Bay, Wisconsin; Milwaukee, Wisconsin; Chicago, Illinois; Gary,
Indiana; Detroit, Michigan; Buffalo, New York; and Cleveland, Ohio. In the absence of strong
synoptic flow, the weather in these major cities, like surrounding coastal communities, is
conditioned as a function of the Great Lakes water temperature. To what extent a lake breeze
influences or is expected to influence the shoreline communities has a significant impact on
energy production via anticipated usage. Using a simple temperature-pressure proportionality,
established atmospheric science arguments show lake breezes modify shoreline wind conditions
in response to a differential horizontal heat flux between land and water as the land heats warmer
than water. The atmosphere seeks to assuage the inland heat with lake-cooled air through the
lake breeze response. Like all mesoscale meteorological features, the resulting temperature and
wind can differ between coastal and near-coastal locales less than five miles apart. This variety
in conditions poses numerous problems in the forecast process and is consistently liable to deter
recreation and commerce near the Great Lakes through conditions which are rarely hazardous,
but often uncomfortable. This problem can be remedied through accessible Great Lakes-focused
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