Frictional secondary circulation near an upwelled thermocline
Csanady, Gabriel T.
MetadataShow full item record
A first order, linear analysis of thermocline upwelling shows that a quasigeostrophic baroclinic jet accompanies the upwelling. The secondary circulation induced in such a flow field in a meridional plane by turbulent friction is investigated. A double Ekman layer is found to form at the thermocline, of a few meters in thickness. The suction of this Ekman layer destroys the primary flow by the "spin-up" mechanism in a period of which the order of magnitude is tentatively estimated at 100 hrs. Thus the primary flow must be reestablished by successive, reasonably frequent wind-stress impulses to maintain a quasi-stationary upwelling. The lower side Ekman layer on the thermocline is fed from a free shear layer (turbulent "Stewartson layer") underneath the free surface -thermocline intersection, which thus becomes an upwelling zone. The width of the turbulent Stewartson layer is estimated to be the velocity difference divided by the Coriolis parameter, i.e. typically of the order of 1 km.
Author Note: The material of this report was presented ten years ago at a symposium, but on account of its speculative nature, remained unpublished. Several colleagues were, however, kind enough to quote it on occasion (e.g. Garrett, 1982) and some have requested copies. In order to make it more readily available, it has now been re-issued as a WHOI report. Paper presented at the Canadian Committee of Oceanography Symposium, Burlington, Ontario, May 4, 1972.
Suggested CitationTechnical Report: Csanady, Gabriel T., "Frictional secondary circulation near an upwelled thermocline", 1982-12, DOI:10.1575/1912/9104, https://hdl.handle.net/1912/9104
Showing items related by title, author, creator and subject.
Holbrook, W. Steven; Fer, Ilker; Schmitt, Raymond W.; Lizarralde, Daniel; Klymak, Jody M.; Helfrich, L. Cody; Kubichek, Robert (American Meteorological Society, 2013-08)Seismic images of oceanic thermohaline finestructure record vertical displacements from internal waves and turbulence over large sections at unprecedented horizontal resolution. Where reflections follow isopycnals, their ...
Farrar, J. Thomas (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2003-09)In this thesis I have endeavored to determine the factors and physical processes that controlled SST and thermocline depth at 10°N, 125°W during the Pan American Climate Study (PACS) field program. Analysis based on the ...
Huang, Rui Xin (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1984-05)Part one of this thesis discusses the structure of the thermocline and the current pattern within a two-layer model. The corresponding flow field is explored as the amount of water in the upper layer is gradually reduced ...