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On methods for estimating oceanic flow
Stockholm University, Faculty of Science, Department of Meteorology.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of this thesis was to estimate and possibly quantify ocean flow by utilizing conventional and novel observational methods as well as model results. Motionally induced voltages, from a cable-based observational system in the Baltic Sea, were analysed to determine their utility for ocean monitoring. The data set was examined as regards the influence of single- and multi-layer flow. Correlation analyses undertaken in the first study showed that the geoelectric installation is capable of providing good estimates of the net flow across the Visby-Västervik transect. The second study focused on possible effects of multi-layer flow on the signal. Comparisons were made with tidal-gauge geostrophic flow estimates, and a good agreement was found, except for a few brief winter periods characterized by significant discrepancies. The velocity fields from a three-dimensional model showed that these events coincided with strong surface and bottom currents, and hence the attenuated voltage signal was suggested as being caused by the non-uniform velocity distribution.

The third study dealt with the deep-water flow through the Understen-Märket trench. Observational data indicated that this flow could be described by applying hydraulic theory. Since the passage is narrow compared to the internal Rossby radius of deformation, rotational effects could be neglected to lowest order. The theoretical predictions proved to agree well with the observational results.

The final study examined the effects of the heat flux and the wind forcing on the circulation in Bahía de Concepción, Chile, where three field surveys were undertaken during the extended austral summer 2002. Hydrographic and current measurements were compared to local tidal-gauge records. Rough estimates of the barotropic and the baroclinic flow across the transect indicated an unusual vortex circulation during periods of weak wind forcing and strong surface heating; results which were corroborated by numerical simulations.

Place, publisher, year, edition, pages
Stockholm: Meteorologiska institutionen (MISU) , 2008. , 23 p.
Keyword [en]
Ocean monitoring techniques, Barotropic flow, Baroclinic flow, Hydraulic theory, Baltic Sea, Bahía de Concepción
National Category
Oceanography, Hydrology, Water Resources
Research subject
Oceanography
Identifiers
URN: urn:nbn:se:su:diva-7343ISBN: 978-91-7155-569-4 (print)OAI: oai:DiVA.org:su-7343DiVA: diva2:198082
Public defence
2008-02-22, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 8 C, Stockholm, 10:00
Opponent
Supervisors
Available from: 2008-02-04 Created: 2008-02-04Bibliographically approved
List of papers
1. Geoelectric monitoring of wind-driven barotropic transports in the Baltic Sea
Open this publication in new window or tab >>Geoelectric monitoring of wind-driven barotropic transports in the Baltic Sea
2007 In: Journal of atmospheric and oceanic technology, Vol. 24, no 9, 1655-1664 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24670 (URN)000249811500010 ()
Note
Part of urn:nbn:se:su:diva-7343Available from: 2008-02-04 Created: 2008-02-04Bibliographically approved
2. Influence of baroclinic flow on motionally-induced voltage measurements
Open this publication in new window or tab >>Influence of baroclinic flow on motionally-induced voltage measurements
In: Journal of atmospheric and oceanic technologyArticle in journal (Refereed) Submitted
Identifiers
urn:nbn:se:su:diva-24671 (URN)
Note
Part of urn:nbn:se:su:diva-7343Available from: 2008-02-04 Created: 2008-02-04Bibliographically approved
3. A note on the deep-water inflow to the Bothnian Sea
Open this publication in new window or tab >>A note on the deep-water inflow to the Bothnian Sea
2007 (English)In: Journal of marine systems, ISSN 0924-7963, Vol. 68, no 1-2, 255-264 p.Article in journal (Refereed) Published
Abstract [en]

The deepest connection between the Bothnian Sea and the Baltic Proper is the narrow Understen-Märket trench with a threshold depth of around 90 m. The deep-water flow through this passage, which is of great importance for the hydrographic state of the entire Gulf of Bothnia, was surveyed by the R/V Aranda in October 2004. On the basis of these field results as well as climatological data, it has been concluded that the deep-water flow can be described using a hydraulic framework applied to a channel of parabolic cross-section. The Understen-Märket trench is sufficiently narrow to, in principle, permits neglect of the Coriolis force. Since it may prove useful for other systems, the study, however, also includes the analysis and evaluation of a scheme to determine rotational first-order corrections to controlled transports predicted using standard non-rotating hydraulic theory.

Keyword
Hydraulics, Rotating fluids, Deep currents, Exchange capacity, Hydrography, Baltic Sea, Bothnian Sea
National Category
Oceanography, Hydrology, Water Resources
Research subject
Oceanography
Identifiers
urn:nbn:se:su:diva-24672 (URN)10.1016/j.jmarsys.2006.12.004 (DOI)000251003400014 ()
Note
Part of urn:nbn:se:su:diva-7343Available from: 2008-02-04 Created: 2008-02-04 Last updated: 2010-01-21Bibliographically approved
4. On the response to wind forcing and heat flux in Bahía de Concepción
Open this publication in new window or tab >>On the response to wind forcing and heat flux in Bahía de Concepción
In: Continental Shelf ResearchArticle in journal (Refereed) Submitted
Identifiers
urn:nbn:se:su:diva-24673 (URN)
Note
Part of urn:nbn:se:su:diva-7343Available from: 2008-02-04 Created: 2008-02-04Bibliographically approved

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