Publication:
The sensitivity of ageostrophic circulations to model resolution: a case study using NGM forecasts of ERICA IOP-4

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Authors
Berdeguez, James
Subjects
Ageostrophic circulations
Psi-vector technique
Model resolution
ERICA
Advisors
Pauley, Patricia M.
Date of Issue
1992-12
Date
December 1992
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
The effect of model resolution on the ageostrohic circulations and dynamics of a rapidly deepening extratropical cyclone that occurred during the Intensive Observing Period (IOP) 4 (4-5 January 1989) of the Experiment on Rapidly Intensifying Cyclones over the Atlantic (ERICA) is examined using the psi-vector technique proposed by Keyser, et al. (1989). A comparison of forecasts made by the National Meteorological Center's Nested Grid Model (NGM) using operations (C-grid_ and double-resolution (D-grid) versions indicated pressure and frontal evolution differences between the two forecasts. The IOP-4 cyclone was observed to deepen by 60 mb in 24 h to a central pressure of 936 mb. The NGM C-grid forecast attained a central pressure at 0000 UTC 5 Jan of 959 mb, while the D-grid forecast attained a central pressure of 949 mb. Differences in this laterally coupled jet streaks between the C- and D-grid forecasts enabled the D-grid forecast to depict stronger transverse ageostrophic circulations that produced stronger ascent and greater spin-up of the low-level cyclone.
Type
Thesis
Description
Series/Report No
Department
Meteorology
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Funder
Format
138 p.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
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.
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