Turbulent Kinetic Energy Dissipation in Barrow Canyon

Abstract

Pacific Water flows across the shallow Chukchi Sea before reaching the Arctic Ocean, where it is a source of heat, freshwater, nutrients, and carbon. A substantial portion of Pacific Water is routed through Barrow Canyon, located in the northeast corner of the Chukchi. Barrow Canyon is a region of complex geometry and forcing where a variety of water masses have been observed to coexist. These factors contribute to a dynamic physical environment, with the potential for significant water mass transformation. The measurements of turbulent kinetic energy dissipation presented here indicate diapycnal mixing is important in the upper canyon. Elevated dissipation rates were observed near the pycnocline, effectively mixing winter and summer water masses, as well as within the bottom boundary layer. The slopes of shear/stratification layers, combined with analysis of rotary spectra, suggest that near-inertial wave activity may be important in modulating dissipation near the bottom. Because the canyon is known to be a hotspot of productivity with an active benthic community, mixing may be an important factor in maintenance of the biological environment.

Transport and thermohaline variability in Barrow Canyon on the Northeastern Chukchi Sea Shelf

“…This additional mass transport would be captured by the mooring array at the mouth of the canyon, but not the array at the head of the canyon. This interpretation is reflected in Shroyer 's [] synoptic sections and in the vertically averaged current statistics from two moorings deployed west of Barrow on the 70 m isobath on the eastern (EBC) and western (WBC) sides of the canyon (Figures a–c). In all 3 years, the vertically averaged flow at WBC was statistically significant and southwestward (or westward in 2012–2013) at ∼1–3 cm s −1 .…”

Distribution and sources of organic matter in surface marine sediments across the North American Arctic margin

“…In particular, BC3 from Barrow Canyon displayed exceptionally high OC loadings (>2.0 mg C m −2 sediment), similar to those observed in sediments from regions of high productivity and low dissolved‐oxygen concentrations [e.g., Hedges and Keil , ]. The head of Barrow Canyon region is recognized as a productivity “hot spot” partly due to dynamic physical mixing [ Shroyer , ] and upwelling of offshore, high‐nutrient upper halocline waters [ Christensen et al ., ; Cooper et al ., ; Mathis et al ., ]. Annual primary production in this area has been estimated at 430 g C m −2 yr −1 (see Table in Grebmeier et al ., [ and references therein]), which is probably the second‐highest estimate for anywhere in the Arctic (behind only the southern Chukchi Sea, which is estimated at 470 g C m −2 yr −1 ).…”

Measuring the Dissipation Rate of Turbulent Kinetic Energy in Strongly Stratified, Low‐Energy Environments: A Case Study From the Arctic Ocean

“…The western Arctic Ocean, where we collected our measurements, is known to be an exceptionally low-energy, and highly stratified, ocean environment with some of the lowest estimates of oceanic turbulence in the world (e.g., Guthrie et al, 2013;Lincoln et al, 2016). Only a relatively small number of microstructure measurements from this region exist to date (e.g., Bourgault et al, 2011;Padman & Dillon, 1987;Rainville & Winsor, 2008;Rippeth et al, 2015;Shaw & Stanton, 2014;Shroyer, 2012), but this number is certain to increase in the coming years owing to increased interest in constraining oceanic heat budgets in the Arctic . Constraining these budgets requires knowledge of turbulent mixing rates in the ocean which are obtained most directly from microstructure measurements; we demonstrate here why this is a challenging endeavor and why special considerations are needed when interpreting those measurements Contours are drawn at 75-m intervals beginning at 50 m. In both panels, color indicates water depth (m); bathymetry data are from the International Bathymetric Chart of the Arctic Ocean 3.0 (Jakobsson et al, 2012).…”