Transport of Pacific Water Into the Canada Basin and the Formation of the Chukchi Slope Current

Abstract

A high-resolution regional ocean model together with moored hydrographic and velocity measurements is used to identify the pathways and mechanisms by which Pacific water, modified over the Chukchi shelf, crosses the shelf break into the Canada Basin. Most of the Pacific water flowing into the Arctic Ocean through Bering Strait enters the Canada Basin through Barrow Canyon. Strong advection allows the water to cross the shelf break and exit the shelf. Wind forcing plays little role in this process. Some of the outflowing water from Barrow Canyon flows to the east into the Beaufort Sea; however, approximately 0.4 to 0.5 Sv turns to the west forming the newly identified Chukchi Slope Current. This transport occurs at all times of year, channeling both summer and winter waters from the shelf to the Canada Basin. The model indicates that approximately 75% of this water was exposed to the mixed layer within the Chukchi Sea, while the remaining 25% was able to cross the shelf during the stratified summer before convection commences in late fall. We view the (0.5) Sv of the Chukchi Slope Current as replacing Beaufort Gyre water that would have come from the east in the absence of the cross-topography flow in Barrow Canyon. The weak eastward flow on the Beaufort slope is also consistent with the local disruption of the Beaufort Gyre by the Barrow Canyon outflow.Plain Language Summary Using a combination of numerical models and field observations, we elucidate where and when waters of Pacific Ocean origin cross the shelf break and enter the interior of the Canada Basin. Most of these waters flow toward the west, forming the recently observed Chukchi Slope Current.Over the years a number of observational and modeling studies have sharpened our view of the circulation and modification of Pacific water as it progresses across the Chukchi shelf. To first order, there are three main

Introduction to Special Collection on Arctic Ocean Modeling and Observational Synthesis (FAMOS) 2: Beaufort Gyre Phenomenon

“…Doddridge et al, ; Manucharyan & Isachsen, ; Proshutinsky, Krishfield, Toole, et al, ; Regan et al, ); identify the major sources of fresh water and the fresh water pathways from the sources to the Beaufort Gyre region (Kelly, Proshutinsky, Popova et al, ); explain the major patterns and regimes of the surface, Pacific, and Atlantic water layer circulation (e.g. Hu & Myers, ; Spall et al, ; Zhong et al, ); and reveal the physics of mechanical mixing and convection under the influence of wind, internal wave, and tidal forcing (e.g., Bebieva & Timmermans, ; Chanona et al, ; Shibley & Timmermans, ; Zhao et al, ). Other papers in the collection examine the role of sea ice conditions, major features of ice variability, and methods of sea ice prediction in the region (e.g.…”

Multi‐Model Intercomparison of the Pan‐Arctic Ice‐Algal Productivity on Seasonal, Interannual, and Decadal Timescales

“…A number of previous studies have indicated that the shelf‐basin exchange of hydrographic and biogeochemical properties across the Chukchi and Beaufort shelf break was induced by mesoscale eddies (e.g., Pickart, ; Spall et al, ; Watanabe et al, ). In addition, a substantial amount of shelf‐origin water is transported from the Barrow Canyon mouth toward the Chukchi Borderland by a narrow boundary current named the Chukchi Slope Current (Corlett & Pickart, ; Spall et al, ; Watanabe et al, ). Thus, in the Canada Basin, crucial nitrate biases are sometimes produced by the coarser‐resolution models which hardly resolve mesoscale eddies and boundary currents.…”

Water Mass Evolution and Circulation of the Northeastern Chukchi Sea in Summer: Implications for Nutrient Distributions

“…This is supported by mooring measurements (Weingartner, Fang, et al, ), shipboard measurements (Pickart et al, ), drifter tracks (Stabeno et al, ), and surface radar measurements (Fang et al, ). Upon exiting Barrow Canyon, the Pacific water forms the eastward‐flowing Beaufort Shelfbreak Jet (Pickart, ) and westward‐flowing Chukchi Slope Current (Corlett & Pickart, ; Li et al, ; Spall et al, ; Stabeno et al, ). The water subsequently enters the Canada Basin via shelf‐basin interactions, for example, eddies (Pickart et al, ), upwelling (Lin, Pickart, Moore, et al, ), and downwelling (Dmitrenko et al, ).…”