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buoyancy budget for a complete ocean basin and showed that net upwelling requires that the area integral of the magnitude of the dianeutral diffusive buoyancy flux must increase with height, but their study did not shed any light on the physical balance that drives the dianeutral upwelling in the bottom boundary layer. In this way, Klocker and McDougall (2010) derived the buoyancy budget (Walin method) for the net upwelling across isopycnals but did not consider the downwelling and upwelling
buoyancy budget for a complete ocean basin and showed that net upwelling requires that the area integral of the magnitude of the dianeutral diffusive buoyancy flux must increase with height, but their study did not shed any light on the physical balance that drives the dianeutral upwelling in the bottom boundary layer. In this way, Klocker and McDougall (2010) derived the buoyancy budget (Walin method) for the net upwelling across isopycnals but did not consider the downwelling and upwelling
-dimensional numerical modeling study. ML12 reported that a few days after the onset of downwelling-favorable wind, the cross-shore circulation within the bottom-attached coastal currents exhibited surface offshore and bottom onshore flow structure (termed upwelling circulation hereinafter). This circulation pattern is opposite to what is expected from the Ekman dynamics (e.g., Ekman 1905 ; Estrade et al. 2008 ). Another two-dimensional modeling study by Shcherbina and Gawarkiewicz (2008) reported a similar
-dimensional numerical modeling study. ML12 reported that a few days after the onset of downwelling-favorable wind, the cross-shore circulation within the bottom-attached coastal currents exhibited surface offshore and bottom onshore flow structure (termed upwelling circulation hereinafter). This circulation pattern is opposite to what is expected from the Ekman dynamics (e.g., Ekman 1905 ; Estrade et al. 2008 ). Another two-dimensional modeling study by Shcherbina and Gawarkiewicz (2008) reported a similar
emphasized, for example, the cross-shore movement of the upwelling front ( Austin and Lentz 2002 ), the dependence upon the turbulence submodel ( Allen et al. 1995 ), and the shelf width effect on the shutdown of the bottom boundary layer ( Oke and Middleton 2000 ). The dynamics of downwelling have been studied by Allen and Newberger (1996) using a two-dimensional numerical model. They show that downwelling winds produce a region of well-mixed fluid inshore of a downwelling front and they observe near
emphasized, for example, the cross-shore movement of the upwelling front ( Austin and Lentz 2002 ), the dependence upon the turbulence submodel ( Allen et al. 1995 ), and the shelf width effect on the shutdown of the bottom boundary layer ( Oke and Middleton 2000 ). The dynamics of downwelling have been studied by Allen and Newberger (1996) using a two-dimensional numerical model. They show that downwelling winds produce a region of well-mixed fluid inshore of a downwelling front and they observe near
have shown that most of the diapycnal mixing activity in the deep ocean occurs above rough bottom topography and is bottom intensified with an e -folding height above the bottom with a typical vertical e -folding length scale of ~500 m ( Kunze et al. 2006 ). The decrease of the magnitude of the diapycnal buoyancy flux with height above the bottom causes a downwelling diapycnal velocity, and this raises the question of how AABW can upwell across isopycnals when the diapycnal mixing activity
have shown that most of the diapycnal mixing activity in the deep ocean occurs above rough bottom topography and is bottom intensified with an e -folding height above the bottom with a typical vertical e -folding length scale of ~500 m ( Kunze et al. 2006 ). The decrease of the magnitude of the diapycnal buoyancy flux with height above the bottom causes a downwelling diapycnal velocity, and this raises the question of how AABW can upwell across isopycnals when the diapycnal mixing activity
where internal ice stresses prevent the pack from freely moving in response to wind forcing. In this case, the friction between the anticyclonic surface ocean geostrophic flow and a relatively stationary sea ice pack gives rise to upwelling (in opposition to downwelling that would arise for the same wind forcing in the absence of sea ice). Indeed, in situ observations from moorings and ice-tethered profilers (ITPs) show current speeds that can be larger than the ice speed, as detailed in the
where internal ice stresses prevent the pack from freely moving in response to wind forcing. In this case, the friction between the anticyclonic surface ocean geostrophic flow and a relatively stationary sea ice pack gives rise to upwelling (in opposition to downwelling that would arise for the same wind forcing in the absence of sea ice). Indeed, in situ observations from moorings and ice-tethered profilers (ITPs) show current speeds that can be larger than the ice speed, as detailed in the
1. Introduction The term “downwelling currents” refers to currents with a downslope mass flux in the bottom boundary layer (BBL). They are also known as cyclonic currents because they flow in the direction of the coastally trapped waves. Examples are the Malvinas and Southland Currents in the Southern Hemisphere and the Oyashio in the Northern Hemisphere. Paradoxically, many of these currents generate the same kind of highly productive ecosystems usually associated with upwelling regimes. The
1. Introduction The term “downwelling currents” refers to currents with a downslope mass flux in the bottom boundary layer (BBL). They are also known as cyclonic currents because they flow in the direction of the coastally trapped waves. Examples are the Malvinas and Southland Currents in the Southern Hemisphere and the Oyashio in the Northern Hemisphere. Paradoxically, many of these currents generate the same kind of highly productive ecosystems usually associated with upwelling regimes. The
-averaged wave height and wavenumber at day 2. Initially the water is at rest and has a stratification with a 20-m-deep thermocline ( Fig. 1b ) mimicking a summertime situation. A spatially uniform wind blows along the shelf and switches direction every 3 days ( Fig. 1c ) mimicking an observed wind case, for example, Chen et al. (2013) . A positive/negative wind stress drives coastal upwelling/downwelling, corresponding to an upwelling/downwelling stage. A complete wind cycle is composed of an upwelling
-averaged wave height and wavenumber at day 2. Initially the water is at rest and has a stratification with a 20-m-deep thermocline ( Fig. 1b ) mimicking a summertime situation. A spatially uniform wind blows along the shelf and switches direction every 3 days ( Fig. 1c ) mimicking an observed wind case, for example, Chen et al. (2013) . A positive/negative wind stress drives coastal upwelling/downwelling, corresponding to an upwelling/downwelling stage. A complete wind cycle is composed of an upwelling
1. Introduction Wind-driven currents play a major role in circulation in coastal regions around the world ( Smith 1995 ). Upwelling and downwelling circulations are of particular interest because of the role their secondary, cross-shelf, circulation plays in redistributing not only heat and salt (and hence density) but also nutrients and biological fields. In this paper, we consider the response to upwelling- and downwelling-favorable winds of a shelf that initially has a strong midwater
1. Introduction Wind-driven currents play a major role in circulation in coastal regions around the world ( Smith 1995 ). Upwelling and downwelling circulations are of particular interest because of the role their secondary, cross-shelf, circulation plays in redistributing not only heat and salt (and hence density) but also nutrients and biological fields. In this paper, we consider the response to upwelling- and downwelling-favorable winds of a shelf that initially has a strong midwater
entrainment occurs at its offshore edge in an initially unstratified water column ( Fong and Geyer 2001 ; Lentz 2004 ). The upwelling-favorable wind-driven current competes with the buoyancy-driven current, which determines the along-shelf transport of plume water ( Whitney and Garvine 2005 ). Even though forced by a downwelling-favorable wind, the steepened isopycnals compress the buoyant coastal current and cross-shore upwelling circulation occurs ( Chen and Chen 2017 ). Although the dynamics of river
entrainment occurs at its offshore edge in an initially unstratified water column ( Fong and Geyer 2001 ; Lentz 2004 ). The upwelling-favorable wind-driven current competes with the buoyancy-driven current, which determines the along-shelf transport of plume water ( Whitney and Garvine 2005 ). Even though forced by a downwelling-favorable wind, the steepened isopycnals compress the buoyant coastal current and cross-shore upwelling circulation occurs ( Chen and Chen 2017 ). Although the dynamics of river
918 JOURNAL OF PHYSICAL OCEANOGRAPHY VOLUME?Coastal Upwelling/Downwelling Cycles in Southern Lake Superior~H. J. NIEBAUER:, TttEODOKE GRw. w.N A~D ROBW. RT A. RACOTZKmMarin, $tudie~ Center, University of Wisconsin, Madison 53706(Manuscript received 18 February 1977, in revised form 30 May 1977) Extensive current meter, hydrographic and wind data were collected, in the region of the KeweenawCurrent, a
918 JOURNAL OF PHYSICAL OCEANOGRAPHY VOLUME?Coastal Upwelling/Downwelling Cycles in Southern Lake Superior~H. J. NIEBAUER:, TttEODOKE GRw. w.N A~D ROBW. RT A. RACOTZKmMarin, $tudie~ Center, University of Wisconsin, Madison 53706(Manuscript received 18 February 1977, in revised form 30 May 1977) Extensive current meter, hydrographic and wind data were collected, in the region of the KeweenawCurrent, a
