Mesoscale predictability under various synoptic regimes
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Authors
Nuss, W.A.
Miller, D.K.
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Date of Issue
2001
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Abstract
Numerical model experiments using slightly rotated
terrain are compared to gauge the sentivity of mesoscale
forecasts to small perturbations that arise due to small
synoptic-scale wind direction errors relative to topographic
features. The surface and above surface wind speed errors,
as well as the precipitation forecast errors, are examined
for a landfalling cold front that occurred during the California
Landfalling Jets (CALJET) experiment. The slight
rotation in the terrain results in nearly identical synopticscale
forecasts, but result in substantial forecast errors on
the mesoscale in both wind and precipitation. The largest
mesoscale errors occur when the front interacts with the topography,
which feeds back on the frontal dynamics to produce
differing frontal structures, which, in turn, result in
mesoscale errors as large as 40% (60%) of the observed
mesoscale variability in rainfall (winds). This sensitivity differs
for the two rotations and a simple average can still have
a substantial error. The magnitude of these errors is very
large given the size of the perturbation, which raises concerns
about the predictability of the detailed mesoscale structure
for landfalling fronts.
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Article
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Meteorology
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Citation
Nonlinear Processes in Geophysics, (2001), Volume 8, pp. 429â 438
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.