Significant variability of structure and predictability of Arctic Ocean surface pathways affects basin-wide connectivity

Abstract

The Arctic Ocean is of central importance for the global climate and ecosystem. It is a region undergoing rapid climate change, with a dramatic decrease in sea ice cover over recent decades. Surface advective pathways connect the transport of nutrients, freshwater, carbon and contaminants with their sources and sinks. Pathways of drifting material are deformed under velocity strain, due to atmosphere-ocean-ice coupling. Deformation is largest at fine space- and time-scales and is associated with a loss of potential predictability, analogous to weather often becoming unpredictable as synoptic-scale eddies interact and deform. However, neither satellite observations nor climate model projections resolve fine-scale ocean velocity structure. Here, we use a high-resolution ocean model hindcast and coarser satellite-derived ice velocities, to show: that ensemble-mean pathways within the Transpolar Drift during 2004–14 have large interannual variability and that both saddle-like flow structures and the presence of fine-scale velocity gradients are important for basin-wide connectivity and crossing time, pathway bifurcation, predictability and dispersion.

Changes in Freshwater Distribution and Pathways in the Arctic Ocean Since 2007 in the Mercator Ocean Global Operational System

“…During the 2008-2011 period, the upper layer waters from the Makarov Basin exited through Fram Strait. Following the northward extension of the BG in 2011, more waters recirculated within the Canada Basin, contributing to freshwater recharge of the BG from the east, which is in agreement with Hu et al (2019) and Wilson et al (2021).…”

Overview of the MOSAiC expedition: Physical oceanography

“…-The observations cover the seasonal cycle across a large part of the Eurasian central Arctic Ocean, often at high temporal resolution for specific processes (e.g., 36-h uninterrupted MSS series), ranging from mixed layer variability to turbulent mixing, double diffusion, and internal waves; -Several measurements encompass an entire basin full-depth, from the surface to the seafloor, and as such can be used to identify biases in a model's representation of the mixed layer depth, vertical stratification and water mass characteristics over the full annual cycle of atmospheric and sea-ice conditions; -The observations are not only point measurements from Polarstern, but also from Ocean City of the other teams, allowing an interdisciplinary approach to study coupled processes and feedbacks of the ocean, ice and air, radiative/heat/ freshwater budgets, turbulent fluxes, carbon cycle, nutrient transports, and trace gas pathways, among others; and -The conditions during 2020 were unique, with an extremely rapid transpolar ice drift, lower sea-ice thicknesses with potential impacts on the transport of the ice-rafted material across the Arctic, stronger oceanic connectivity between the western Siberian shelves and the central Arctic Ocean and a record shift from an extremely low to an extremely high Arctic Oscillation in winter (Dethloff et al, 2021;Krumpen et al, 2021;Rinke et al, 2021;Wilson et al, 2021).…”

“…Another example of the joint modeling and observational effort is to examine sub-mesoscale and mesoscale eddy statistics, and to improve their parameterization using data and high-resolution modeling (e.g., Danilov et al, 2017;Kubryakov et al, 2021). A further aspect is to explore largescale dynamical structures in the surface ice and ocean flows (Wilson et al, 2021). On the interdisciplinary side, ongoing modeling of the pan-Arctic advection of heat, nutrients, and other biogeochemically relevant substances by sea ice and ocean gives crucial input to predict the near future of the Arctic in response to climate change (e.g., Ardyna and Arrigo, 2020;.…”

Arctic – Atlantic Exchange of the Dissolved Micronutrients Iron, Manganese, Cobalt, Nickel, Copper and Zinc With a Focus on Fram Strait

“…The southward extent of these elevated surface concentrations is so far undetermined. However, whilst surface drift pathways across the central Arctic Ocean are subject to considerable interannual variability (Wilson et al., 2021), recent repeat sections of radium indicate that the cross‐Arctic transfer of shelf derived elements increased from 2007 to 2015 (Kipp et al., 2018), with potential consequences for micronutrient export through Fram Strait (Mauritzen et al., 2013; Rudels, 2019).…”