Arctic pathways of Pacific Water: Arctic Ocean Model Intercomparison experiments

Abstract

Pacific Water (PW) enters the Arctic Ocean through Bering Strait and brings in heat, fresh water, and nutrients from the northern Bering Sea. The circulation of PW in the central Arctic Ocean is only partially understood due to the lack of observations. In this paper, pathways of PW are investigated using simulations with six state‐of‐the art regional and global Ocean General Circulation Models (OGCMs). In the simulations, PW is tracked by a passive tracer, released in Bering Strait. Simulated PW spreads from the Bering Strait region in three major branches. One of them starts in the Barrow Canyon, bringing PW along the continental slope of Alaska into the Canadian Straits and then into Baffin Bay. The second begins in the vicinity of the Herald Canyon and transports PW along the continental slope of the East Siberian Sea into the Transpolar Drift, and then through Fram Strait and the Greenland Sea. The third branch begins near the Herald Shoal and the central Chukchi shelf and brings PW into the Beaufort Gyre. In the models, the wind, acting via Ekman pumping, drives the seasonal and interannual variability of PW in the Canadian Basin of the Arctic Ocean. The wind affects the simulated PW pathways by changing the vertical shear of the relative vorticity of the ocean flow in the Canada Basin.

Arctic Ocean outflow and glacier–ocean interactions modify water over the Wandel Sea shelf (northeastern Greenland)

“…This is consistent with an earlier proposition by Rudels et al (2004), downstream observations along the southeast coast of Greenland (e.g., Bacon et al, 2002;Sutherland and Pickart, 2008;Sutherland et al, 2009) and numerical simulations (Hu and Myers, 2013;Aksenov et al, 2016). Finally, we note that our observations were not accompanied by water sampling for determining the nitrate-phosphate relationship commonly used to trace the Pacific water in the Arctic Ocean and Greenland Sea.…”

“…The freshwater export through the western Fram Strait is an important component of the Arctic Ocean freshwater budget that links the Arctic Ocean to the global climate system (e.g., de Steur et al, 2009). The coastal branch of the Pacific water flow along the southeast coast of Greenland was reported based on observations (e.g., Bacon et al, 2002;Sutherland and Pickart, 2008;Sutherland et al, 2009) and numerical simulations (Hu and Myers, 2013;Aksenov et al, 2016). However, the pathways of the low-salinity Pacific water along the northeast coast of Greenland are debatable.…”

A 4.5 km resolution Arctic Ocean simulation with the global multi-resolution model FESOM 1.4

“…Despite a lot of success in modeling studies of the Arctic Ocean, the state-of-the-art ocean general circulation models still show non-negligible model biases, as illustrated by different model intercomparison studies (Jahn et al, 2012;Johnson et al, 2012;Aksenov et al, 2016;Wang et al, 2016a, b;Ilicak et al, 2016). For example, in the earlier Arctic Ocean Intercomparison Project (AOMIP; Proshutinsky and Kowalik, 2007;Proshutinsky et al, 2011), it was identified that too-thick Atlantic Water layers in the Arctic Ocean were simulated in the models, very possibly due to spurious numerical mixing (Holloway et al, 2007;Karcher et al, 2007).…”

On deep convection events and Antarctic Bottom Water formation in ocean reanalysis products

“…Green's function method is used to calibrate the control variables (Menemenlis et al, 2008) and the initial parameters, which include initial temperature and salinity conditions; background vertical diffusivity; atmospheric surface boundary conditions; critical Richardson numbers; air-ocean, ice-ocean and air-ice drag coefficients; albedo coefficients of ice, ocean and snow; and bottom drag and vertical viscosity. ECCO2 is run directly from its initial conditions, without the use of a spinup period to bring the model to equilibrium (Aksenov et al, 2016). The ECCO2 reanalysis product spans from 1992 to 2012, with a 0.25 • × 0.25 • horizontal resolution and 50 unevenly spaced vertical levels (Menemenlis et al, 2008).…”