Shelfbreak circulation in the Alaskan Beaufort Sea: Mean structure and variability

Abstract

Historical hydrographic and current meter data are used to investigate the properties and circulation at the shelf edge of the Alaskan Beaufort Sea. Thirty‐three individual cross‐sections, spanning the time period 1950 to 1987, are combined in a topographical framework to produce mean vertical hydrographic sections, as well as a section of mean absolute geostrophic velocity referenced using the current meter data. This reveals the presence of a narrow (order 20 km) eastward current, referred to as the Beaufort shelfbreak jet. The jet has three distinct seasonal configurations: In late‐spring to late‐summer, cold, winter‐transformed Bering water is advected in a subsurface current; from mid‐summer to early fall a surface intensified current advects predominantly Bering summer water; and from mid‐fall to mid‐spring, under easterly winds, the jet transports upwelled Atlantic water. The volume transport of the jet represents a significant fraction of the inflowing transport through Bering Strait. While the characteristics and flow of the winter‐transformed Bering water vary interannually, this water mass ventilates predominantly the upper halocline.

Vertical stability and the annual dynamics of nutrients and chlorophyll fluorescence in the coastal, southeast Beaufort Sea

“…The warm surface temperatures on 22 December (À1.1°C) relative to the bracketing time points (À1.6°C) lend further support to this hypothesis (Figure 3). Such a warm anomaly requires the continual, upward mixing of heat and is inconsistent with long-range Ekman drift (of waters upwelled elsewhere) or an intrusion of the Beaufort shelf-break jet [Pickart, 2004]. The hullmounted ship ADCP recorded relatively strong currents from À25 to +20 cm s À1 during the anomaly, with the current changing direction on 25 December.…”

Water mass and bathymetric characteristics of polar cod habitat along the continental shelf and slope of the Beaufort and Chukchi seas

“…As the ACC leaves Barrow Canyon and Xows toward the Beaufort shelf, it combines with the Central Channel Xow to create a strong and narrow coastal jet that follows the Beaufort Shelf topography eastward toward the Mackenzie Canyon (Pickart 2004;Winsor and Chapman 2004). There it mixes with the outXow of the Mackenzie River, which generally also Xows eastward and spreads out across the Mackenzie Shelf (also called the Canadian Shelf).…”

Ocean currents shape the microbiome of Arctic marine sediments

“…During summer, as ice melts and vertical mixing is reduced, water on the ABS is density stratified, resulting in a layer of Pacific origin water sandwiched between an Arctic surface layer, and a deep, cold and saline layer of Atlantic origin water (Carmack and Macdonald, 2002;McLaughlin et al, 2004;Shimada et al, 2005). The halocline (40-100 m) between surface and Pacific water and pycnocline (200 m) between Pacific and Atlantic water physically separates these masses (McLaughlin et al, 2004;Pickart, 2004). During stratified periods, free-living microorganisms are resistant to sinking through boundary layers (Jonas, 1997;Hamdan and Jonas, 2006) and will become entrained in a water mass (Agogue et al, 2011).…”