ISSN:
1436-5065
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geography
,
Physics
Notes:
Summary 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, wheref is the Coriolis parameter and ω is the frequency of the wind oscillation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01029695
Permalink
