Abstract
AbstractAtlantic Water takes various pathways through the Nordic Seas, and its transformation to denser waters forms a crucial connection to the lower limb of the Atlantic Meridional Overturning Circulation. Circulation maps often schematize two distinct pathways of Atlantic Water: one following the Norwegian Atlantic Slope Current along the continental slope of Norway and one following the Norwegian Atlantic Front Current along the Mohn and Knipovich Ridges. In this paper, the connectivity between the northward flow along these ridges is investigated. Analyzing trajectories of surface drifters and ARGO floats, we find that only 8% of the floats that travel near the mid‐ocean ridges take the frontal pathway to the north. Indeed, by tracing numerical particles in a realistic numerical simulation, part of the water mass traveling along the Mohn Ridge follows the 2,500 m isobath eastward and joins the slope current, instead of flowing north along the Knipovich Ridge. Furthermore, north of 74°N, frequent exchange between the slope current and the front current is observed. Therefore, the slope current and front current are less isolated than often schematized. Additionally, the observational data set reveals substantial cross‐ridge exchange; 31% of the floats that travel within 60 km from the mid‐ocean ridges cross it. Results from numerical simulations indicate that the cross‐ridge exchange leads to cooling and freshening of the Atlantic Water along the front. Deployments of floats near the mid‐ocean ridges are needed to investigate the pathway of Atlantic Water and its exchange across the ridge in more detail.
Highlights
The Nordic Seas are characterized by a warm and saline Atlantic water mass in the east and a fresh and cold Arctic water mass in the west
Analyzing trajectories of surface drifters and ARGO floats, we find that only 8% of the floats that travel near the mid‐ocean ridges take the frontal pathway to the north
As ARGO floats and surface drifters float at a fixed depth, they are unable to represent any vertical displacement of water masses, which is likely to occur in the Nordic Seas
Summary
The Nordic Seas are characterized by a warm and saline Atlantic water mass in the east and a fresh and cold Arctic water mass in the west. The AF is characterized by a strong thermocline and halocline that separate the Arctic Water in the west from the AW in the east (Figure 1b Bosse & Fer, 2019) This density front is aligned with the mid‐ocean topographic ridges in the Nordic Seas: the Mohn Ridge and the Knipovich Ridge (see Figure 1a). The conclusion drawn by Orvik and Niiler (2002), that the NwAC maintains a two‐branch structure throughout the Nordic Seas, was based on a composite of many partial pathways of surface drifters It can be questioned whether these pathways apply to water parcels that come from south of 65°N and travel all the way to the Arctic.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
