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Robinson, Walter A. Huang, Huei-Ping 2015-09-28T14:52:25Z 2015-09-28T14:52:25Z 10000-01-01 1997 1997 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. Made available in DSpace on 2015-09-28T14:52:25Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 9737135.pdf: 8214260 bytes, checksum: e891cb069a624e2bbbbdee9be3e2625a (MD5) Previous issue date: 1997 Embargo set by: Seth Robbins for item 87261 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 178 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997. http://hdl.handle.net/2142/85980 (MiAaPQ)AAI9737135 eng Physics, Atmospheric Science Barotropic Model Simulations of Low-Frequency Variability text Atmospheric Sciences Atmospheric Sciences University of Illinois at Urbana-Champaign Dissertation Ph.D.