Search Results

You are looking at 1 - 10 of 175 items for :

  • Geographic location/entity x
  • Journal of Physical Oceanography x
  • All content x
Clear All
Leandro Ponsoni, Borja Aguiar-González, Herman Ridderinkhof, and Leo R. M. Maas

computation of the geostrophic velocity field and its associated transport (e.g., Fomin 1964 ) depends on the choice of a velocity reference level (and salinity estimates in the XBT case). Additionally, factors such as time variability, geographical location, and differences in the horizontal and vertical scales involved in the geostrophic calculations also contributed to the disparities in the EMC volume transport found in the literature: 20–24 Sv ( Wyrtki 1971 ), 35 Sv ( Harris 1972 ), 41 Sv

Full access
Yeping Yuan and Alexander R. Horner-Devine
Full access
Anthony R. Poggioli and Alexander R. Horner-Devine

control—that is, the flow is critical there—in the absence of varying channel topography. However, if there are significant lateral constrictions present in the estuary, the relevant control may be a channel constriction and not the river mouth. This is because flow constrictions satisfy the regularity conditions, which are necessary local topographic conditions (e.g., db / dx = 0) for the existence of a hydraulic control ( Armi 1986 ). Denoting the location of the control as x = 0, the first

Full access
Michael A. Spall

world in any detailed manner, names based on the real geography will be used to describe the model configuration and in discussion of the results. The maximum bottom depth is 1000 m, with a 100-km-wide region of sloping topography around the basin perimeter. The actual Arctic Ocean is much deeper than 1000 m, but the main focus of this study in on the circulation in the Atlantic layer (shallower than 1000 m) and development of the halocline. There is a 300-m-tall ridge that separates the Arctic

Full access
Edward D. Zaron and David A. Jay

level records (stations west of the date line). Table 2. Hourly Sea level records (stations east of the date line). The stations are located throughout the North and South Pacific; although, a disproportionate number are located on the Hawaiian Islands, and there are only three stations to the east of 210°E ( Fig. 1 ). The stations were selected from the UHSLC holdings based on the length of the time series at each site and on their location away from continental shelves and coasts. All of the

Full access
K. H. Brink and H. Seo

1. Introduction For a range of continental shelf locations, Kundu and Allen (1976) , along with several subsequent investigators (e.g., Winant 1983 ; Dever 1997 ; S. Lentz 2015, personal communication), have demonstrated a striking discrepancy between large correlation length scales for middepth subtidal alongshore velocity versus shorter scales for cross-shelf velocity. This order of magnitude discrepancy is far greater than can be accounted for by the natural scale differences for

Full access
Jason D. Flanagan, Timour Radko, William J. Shaw, and Timothy P. Stanton

Abstract

This study examines the interaction of diffusive convection and shear through a series of 2D and 3D direct numerical simulations (DNS). The model employed is based on the Boussinesq equations of motion with oscillating shear represented by a forcing term in the momentum equation. This study calculates thermal diffusivities for a wide range of Froude numbers and density ratios and compares the results with those from the analysis of observational data gathered during a 2005 expedition to the eastern Weddell Sea. The patterns of layering and the strong dependence of thermal diffusivity on the density ratio described here are in agreement with observations. Additionally, the authors evaluate salinity fluxes that are inaccessible from field data and formulate a parameterization of buoyancy transport. The relative significance of double diffusion and shear is quantified through comparison of density fluxes, efficiency factor, and dissipation ratio for the regimes with/without diffusive convection. This study assesses the accuracy of the thermal production dissipation and turbulent kinetic energy balances, commonly used in microstructure-based observational studies, and quantifies the length of the averaging period required for reliable statistics and the spatial variability of heat flux.

Full access
Peter E. D. Davis, Camille Lique, Helen L. Johnson, and John D. Guthrie

Abstract

The Arctic Ocean is undergoing a period of rapid transition. Freshwater input is projected to increase, and the decline in Arctic sea ice is likely to drive periodic increases in vertical mixing during ice-free periods. Here, a 1D model of the Arctic Ocean is used to explore how these competing processes will affect the stratification, the stability of the cold halocline, and the sea ice cover at the surface. Initially, stronger shear leads to elevated vertical mixing that causes the mixed layer to warm. The change in temperature, however, is too small to affect the sea ice cover. Most importantly, in the Eurasian Basin, the elevated shear also deepens the halocline and strengthens the stratification over the Atlantic Water thermocline, reducing the vertical heat flux. After about a decade this effect dominates, and the mixed layer begins to cool. The sea ice cover can only be significantly affected if the elevated mixing is sufficient to erode the stratification barrier associated with the cold halocline. While freshwater generally dominates in the Canadian Basin (further isolating the mixed layer from the Atlantic Water layer), in the Eurasian Basin elevated shear reduces the strength of the stratification barrier, potentially allowing Atlantic Water heat to be directly entrained into the mixed layer during episodic mixing events. Therefore, although most sea ice retreat to date has occurred in the Canadian Basin, the results here suggest that, in future decades, elevated vertical mixing may play a more significant role in sea ice melt in the Eurasian Basin.

Full access
Andre Staalstrøm, Lars Arneborg, Bengt Liljebladh, and Göran Broström

1. Introduction Flow–topography interactions caused by stratified flow over, around, and through rough topography are important for mixing in the deep abyssal ocean (e.g., Ledwell et al. 2000 ), over the shelf (e.g., Nash and Moum 2001 ), and in fjords (e.g., Arneborg and Liljebladh 2009 ). Fjord entrances with sills are typical locations of strong flow–topography interactions due to strong barotropic and baroclinic currents caused by tides and exchange processes between the fjord and the

Full access
K. H. Brink

), alongshore correlation scales for alongshore currents would be somewhat larger than for cross-shelf currents, but the discrepancy would be nowhere near as dramatic as that found by Kundu and Allen. Comparably complete measurements from other continental shelf locations have produced similar results for length scales, for example, for Peru near 15°S ( Brink et al. 1980 , their appendixes), off northern California ( Dever 1997 ), off southern California ( Winant 1983 ), and in the Middle Atlantic Bight (S

Full access