Analytical investigations of horizontal meso-scale momentum equations with Newtonian nudging

X. M. Cai, D. G. Steyn, Itsushi Uno

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

This study presents an analytical investigation of the local behaviour of the solution to a mesoscale model with Newtonian nudging when observed winds are time varying. The analysis examines each Fourier component of the time series of observed winds. Unlike the case with a constant observed wind, the nudged wind vector does not asymptotically approach the observed wind. In response to sinusoidal oscillation of the observed wind, the nudged wind vector is always on a half circle connecting the vector ends of the observed and un-nudged modelled winds. When nudging parameter α → 0, the nudged wind vector approaches the un-nudged wind; when α → ∞, the nudged wind vector approaches the observed wind. For commonly used values of nudging parameter α, the modelled wind field always carries errors. A target nudging scheme is devised in this study in order to ensure the model result is identical to observed winds with sinusoidal oscillation. Investigation shows that such a target wind exists for a finite value of α, and the magnitude of the target-nudging term is about the same as that of a normal nudging term if α ∼ f ∼ ω, where f is the Coriolis parameter and ω is the frequency of the wind oscillation.

Original languageEnglish
Pages (from-to)231-241
Number of pages11
JournalMeteorology and Atmospheric Physics
Volume64
Issue number3-4
DOIs
Publication statusPublished - Jan 1 1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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