Barotropic Model Simulations of Low-Frequency Variability

Huang, Huei-Ping

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Description

Title

Barotropic Model Simulations of Low-Frequency Variability

Author(s)

Huang, Huei-Ping

Issue Date

1997

Doctoral Committee Chair(s)

Robinson, Walter A.

Department of Study

Atmospheric Sciences

Discipline

Atmospheric Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Physics, Atmospheric Science

Language

eng

Abstract

Unforced, subcritical nonlinear simulations fail to produce meaningful variability, indicating that forcing is necessary in maintaining the low-frequency variability in the barotropic system under subcritical condition. Stochastically forced experiments are conducted using spatially homogeneous forcing. In the weakly subcritical cases, the model produces spatially and temporally coherent variability, with the first two EOFs of the perturbation field resembling the phase quadrature of the leading normal mode. In this case, the normal mode and retrograde wave structures emerge without normal mode instability. In the strongly subcritical cases, the stochastically forced solutions generally exhibit poor coherence. A stochastically-driven scenario works only in the weakly subcritical regime. The characteristics of the optimal perturbations in the barotropic system are examined. A more general type of spectrally-constrained optimal perturbation is discussed.

Graduation Semester

1997

Type of Resource

text

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