On the response of a buoyant plume to downwelling-favorable wind stress
Citable URI
https://hdl.handle.net/1912/5361As published
https://doi.org/10.1175/JPO-D-11-015.1DOI
10.1175/JPO-D-11-015.1Keyword
Baroclinic flows; Boundary currents; Coastal flows; Upwelling/downwelling; Wind; Ocean modelsAbstract
Here, the response of a coastally trapped buoyant plume to downwelling-favorable wind forcing is explored using a simplified two-dimensional numerical model and a prognostic theory for the resulting width, depth, and density anomaly and along-shelf transport of the plume. Consistent with the numerical simulations, the analytical model shows that the wind causes mixing of the plume water and that the forced cross-shelf circulation can also generate significant deepening and surface narrowing, as well as increased along-shelf transport. The response is due to a combination of the purely advective process that leads to the steepening of the isopycnals and the entrainment of ambient water into the plume. The advective component depends on the initial plume geometry: plumes that have a large fraction of their total width in contact with the bottom (“bottom trapped”) suffer relatively small depth and width changes compared to plumes that have a large fraction of their total width detached from the bottom (“surface trapped”). Key theoretical parameters are Wγ/Wα, the ratio of the width of the plume detached from the bottom to the width of the plume in contact with it, and the ratio of the wind-generated mixed layer δe to the initial plume depth hp, which determines the amount of water initially entrained into the plume. The model results also show that the cross-shelf circulation can be strongly influenced by the wind-driven response in combination with the geostrophic shear of the plume. The continuous entrainment into the plume, as well as transient events, is also discussed.
Description
Author Posting. © American Meteorological Society, 2012. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 42 (2012): 1083–1098, doi:10.1175/JPO-D-11-015.1.
Collections
Suggested Citation
Journal of Physical Oceanography 42 (2012): 1083–1098Related items
Showing items related by title, author, creator and subject.
-
Downwelling wind, tides, and estuarine plume dynamics
Lai, Zhigang; Ma, Ronghua; Huang, Mingfen; Chen, Changsheng; Chen, Yong; Xie, Congbin; Beardsley, Robert C. (John Wiley & Sons, 2016-06-24)The estuarine plume dynamics under a downwelling-favorable wind condition were examined in the windy dry season of the Pearl River Estuary (PRE) using the PRE primitive-equation Finite-Volume Community Ocean Model (FVCOM). ... -
The effects of thermohaline circulation on wind-driven circulation in the South China Sea
Wang, Guihua; Huang, Rui Xin; Su, Jilan; Chen, Dake (American Meteorological Society, 2012-12)The dynamic influence of thermohaline circulation on wind-driven circulation in the South China Sea (SCS) is studied using a simple reduced gravity model, in which the upwelling driven by mixing in the abyssal ocean is ... -
The response of a weakly stratified layer to buoyancy forcing
Pedlosky, Joseph (American Meteorological Society, 2009-04)The response of a weakly stratified layer of fluid to a surface cooling distribution is investigated with linear theory in an attempt to clarify recent numerical results concerning the sinking of cooled water in polar ocean ...