Axially-symmetric, linear modes of global, primitive equation, ocean-atmosphere models are examined to see if they contain decadal ($\sim$10-30 years) oscillation time scale modes. / A two-layer model of the global ocean and a two-level model of the global atmosphere are formulated. Both models are linearized about axially-symmetric basic states containing mean meridional circulations in the ocean and the atmosphere. The linearized perturbation system is solved as an eigenvalue problem. Uncoupled, axially-symmetric modes of oscillation of the ocean and the atmosphere are calculated. Axially-symmetric modes of the coupled ocean-atmosphere system are also calculated. Sensitivity of the results to various physical processes and parameter values are examined. / The main conclusion of this study is that linearized, uncoupled and coupled ocean-atmosphere systems in the presence of basic states containing mean meridional circulations can generate axially-symmetric modes of variability on decadal time scales. The spatial structures of uncoupled and coupled decadal modes, however, are quite different. Some of the decadal modes have meridional structures that are comparable to the meridional structures of the observed axially-symmetric modes of oscillations of sea level pressure and sea surface temperature over the Pacific Ocean. Families of decadal period, growing modes in the coupled ocean-atmosphere model exist for a number of sensitivity experiments carried out in this study. / It is shown with a scale analysis that the same mechanism operates to generate variability of the axially-symmetric atmospheric modes on time scales of weeks to decades and variability of the axially-symmetric oceanic modes on time scales of years to centuries. The two most important processes in both the systems are the advection of perturbation fields by basic state meridional velocity and the advection of basic state fields by perturbation meridional velocity. The latter is crucial for the existence of the oscillations. / There are axially-symmetric modes in the uncoupled and coupled models on El Nino-Southern Oscillation and intra-seasonal time scales also. / Source: Dissertation Abstracts International, Volume: 51-04, Section: B, page: 1878. / Major Professor: Jon E. Ahlquist. / Thesis (Ph.D.)--The Florida State University, 1990.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_78245 |
| Contributors | Mehta, Vikram Madhuvadan., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 198 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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