On the Origin of Water Masses in the Beaufort Gyre

Abstract

The Beaufort Gyre is a key feature of the Arctic Ocean, acting as a reservoir for freshwater in the region. Depending on whether the prevailing atmospheric circulation in the Arctic is anticyclonic or cyclonic, either a net accumulation or release of freshwater occurs. The sources of freshwater to the Arctic Ocean are well established and include contributions from the North American and Eurasian Rivers, the Bering Strait Pacific water inflow, sea ice meltwater, and precipitation, but their contribution to the Beaufort Gyre freshwater accumulation varies with changes in the atmospheric circulation. Here we use a Lagrangian backward tracking technique in conjunction with the 1/12‐degree resolution Nucleus for European Modelling of the Ocean model to investigate how sources of freshwater to the Beaufort Gyre have changed in recent decades, focusing on increase in the Pacific water content in the gyre between the late 1980s and early 2000s. Using empirical orthogonal functions we analyze the change in the Arctic oceanic circulation that occurred between the 1980s and 2000s. We highlight a “waiting room” advective pathway that was present in the 1980s and provide evidence that this pathway was caused by a shift in the center of Ekman transport convergence in the Arctic. We discuss the role of these changes as a contributing factor to changes in the stratification, and hence potentially the biology, of the Beaufort Gyre region.

Analysis of the Beaufort Gyre Freshwater Content in 2003–2018

“…The distribution of tracers from these sources (Figure ) is in agreement with our conclusions. Our results are also supported by simulations of particles released in the Beaufort Gyre (Kelly et al, ; this special issue) and using a backward trajectories method to track particle origins based on results of the 1/12° NEMO model. It was found that pathways of fresh water from Mackenzie and Bering Strait depend significantly on the sense and intensity of the atmospheric circulation regime and that since 2000, the contribution of fresh water from the Mackenzie River to the accumulation in the Beaufort Gyre region was comparable with the freshwater volume transported to the region from Bering Strait.…”

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

“…Results of Proshutinsky, Krishfield, Toole, et al (2019) are supported by simulations using the 1/12°NEMO model of particles released in the Beaufort Gyre employing a method of backward trajectories to track particle origins (Kelly, Proshutinsky, Popova et al, 2018; this special collection). It was found that pathways of fresh water from Mackenzie and Bering Strait depend significantly on the sense and intensity of the atmospheric circulation, which has been predominantly anticyclonic since 1997.…”

“…The 2003–2018 time series of atmospheric, sea ice, oceanic, and biogeochemistry data, combined with Arctic coupled ice‐ocean modeling with atmospheric forcing, have been used to investigate the major causes, consequences, and rates of Beaufort Gyre freshwater accumulation and release (e.g. 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, ).…”

They Came From the Pacific: How Changing Arctic Currents Could Contribute to an Ecological Regime Shift in the Atlantic Ocean

“…Kelly et al () investigated how well NEMO reproduced sea ice coverage and how the modeled SSH and barotropic streamfunction compared to satellite measurements (Armitage et al, ). This was expanded upon in Kelly et al (), where the modeled mixed layer was validated against observational data (Peralta‐Ferriz & Woodgate, ) and good model skill was found. Similar configurations of NEMO have been further validated, with modeled water mass types and stratification found to be in agreement with observations (Aksenov et al, ; Janout et al, ; Luneva et al, ).…”

“…Outflow from the Arctic to the Atlantic Ocean (via Fram and Davis Straits) was investigated in a coarser ¼ resolution version of NEMO (Lique et al, ). Other questions, including the dynamics of the Beaufort Gyre (Kelly et al, ) and the fate of potential oil spills from Arctic shipping (Kelly et al, ), have used ARIANE alongside the same configuration of NEMO employed in this paper.…”