Landfalling Cyclone Forecast Sensitivity to Varying Data Assimilation Methods in a Mesoscale Model
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Authors
Nuss, Wendell A.
Miller, Douglas K.
Subjects
Advisors
Date of Issue
2001
Date
2001
Publisher
Language
Abstract
During PACJET 2001, an intense extratropical
cyclone rapidly developed off the Southern
California coast and produced substantial rainfall
as it interacted with coastal topography.
Operational models tended to misplace the
position and underforecast the intensity of the
storm, which was due in part to a lack of
observations over the cyclogenesis region off the
coast of Southern California. PACJET made
dropsonde and other insitu observations in the
area, which were available for data assimilation
tests using the Navy's COAMPS model.
Previous work has suggested that orographic
rainfall predictions by a mesoscale model are
sensitive to details in the specification of initial
conditions. Nuss and Miller (2001) found
significant differences in mesoscale precipitation
for a landfalling front interacting with coastal
topography that was rotated by 1 degree relative
to the large scale wind direction. Their results
suggest that in some situations the terrain forced
precipitation can be sensitive to small differences
in the synoptic-scale structure. In this study, the
sensitivity of the cyclogenesis and subsequent
orographic rainfall to the choice of data
assimilation method is examined. The range of
forecast errors and character of the forecast
differences are examined to highlight crucial
aspects in the initial state that must be faithfully
represented by the assimilation system to
accurately predict the cyclogenesis and
orographic rainfall.
Type
Conference Paper
Description
Extended Abstract
Series/Report No
Faculty & Researcher Publications
Department
Meteorology
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funding
Format
3 p.
Citation
Distribution Statement
Rights
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.