Show simple item record

dc.contributor.authorCapontondi, Antonietta  Concept link
dc.coverage.spatialGulf Stream
dc.date.accessioned2012-11-06T20:12:10Z
dc.date.available2012-11-06T20:12:10Z
dc.date.issued1993-02
dc.identifier.urihttps://hdl.handle.net/1912/5512
dc.descriptionSubmitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 1993en_US
dc.description.abstractThe dynamical aspects involved in the assimilation of altimeter data in a numerical ocean model have been investigated. The model used for this study is a quasi-geostrophic model of the Gulf Stream region. The data that have been assimilated are maps of sea surface height which have been obtained as the superposition of sea surface height variability deduced from the Geosat altimeter measurements and a mean field constructed from historical hydrographic data. The method used for assimilating the data is the nudging technique. Nudging has been implemented in such a way as to achieve a high degree of convergence of the surface model fields toward the observations. We have analyzed the mechanisms of the model adjustment, and the final statistical equilibrium characteristics of the model simulation when the surface data are assimilated. Since the surface data are the superposition of a mean component and an eddy component, in order to understand the relative role of these two components in determining the characteristics of the final st atistical steady state, we have considered two different experiments: in the first experiment only the climatological mean field is assimilated, while in the second experiment the total surface streamfunction field (mean + eddies) has been used. We have found that the mean component of the surface data determines, to a large extent, the structure of the flow field in the subsurface layers, while the eddy field, as well as the inflow/outflow conditions at the open boundaries, affect its intensity. In particular, if surface eddies are not assimilated only a weak flow develops in the two deeper model layers where no inflow/ outflow is prescribed at the boundaries. Comparisons of the assimilation results with available in situ observations show a considerable improvement in the degree of realism of the climatological model behavior, with respect to the model in which no data are assimilated. In particular, the possibility of building into the model more realistic eddy characteristics, through the assimilation of the surface eddy field, proves very successful in driving components of the mean model circulation that are in good agreement with the available observations.en_US
dc.description.sponsorshipThis research was carried out with the support of the National Aeronaut ics Space Administration, through a contract to MIT from the Jet Propulsion Laboratory, # 958208, as a part of the TOPEX-Poseidon investigation.en_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherMassachusetts Institute of Technology and Woods Hole Oceanographic Institutionen_US
dc.relation.ispartofseriesWHOI Thesesen_US
dc.subjectOcean-atmosphere interactionen_US
dc.subjectOcean currentsen_US
dc.subjectOcean temperatureen_US
dc.titleAssimilation of altimeter data in a quasi-geostrophic model of the Gulf Stream system : a dynamical perspectiveen_US
dc.typeThesisen_US
dc.identifier.doi10.1575/1912/5512


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record