Seasonal overturning variability in the eastern North Atlantic subpolar gyre: a Lagrangian perspective

6Citations
Citations of this article
12Readers
Mendeley users who have this article in their library.
Get full text

Abstract

Both observations and ocean reanalyses show a pronounced seasonality in the strength of the Atlantic meridional overturning circulation (MOC) within the eastern North Atlantic subpolar gyre (eSPG). However, attributing this overturning seasonality to seasonal dense water formation remains challenging owing to the wide distribution of recirculation timescales within the Iceland and Irminger basins. Here, we investigate the nature of seasonal overturning variability using Lagrangian water parcel trajectories initialised across the Overturning in the Subpolar North Atlantic Program (OSNAP) East section within an eddy-permitting ocean sea ice hindcast. By adopting a Lagrangian perspective, we show that the seasonal minimum of the Eulerian overturning at OSNAP East in autumn results from a combination of enhanced stratification and increased southward transport within the upper East Greenland Current. This convergence of southward transport within the MOC upper limb is explained by decreasing water parcel recirculation times in the upper Irminger Sea, consistent with a gyre-scale response to seasonal wind forcing. To account for the diversity of recirculation times within the eSPG, we also quantify the Lagrangian overturning (LMOC) as the total dense water formation along water parcel trajectories. The majority of water parcels, sourced from the central and southern branches of the North Atlantic Current, fail to return to OSNAP East prior to experiencing wintertime diapycnal transformation into the lower limb, and thus they determine the mean strength of the LMOC within the eSPG (8.9 ± 2.2 Sv). The strong seasonality of the LMOC is explained by a small collection of upper-limb water parcels, circulating rapidly (≤ 8.5 months) in the upper Irminger and central Iceland basins, whose along-stream transformation is determined by their month of arrival at OSNAP East.

References Powered by Scopus

The ERA-Interim reanalysis: Configuration and performance of the data assimilation system

20576Citations
N/AReaders
Get full text

Decadal trends in the North Atlantic oscillation: Regional temperatures and precipitation

6639Citations
N/AReaders
Get full text

The ERA-40 re-analysis

6151Citations
N/AReaders
Get full text

Cited by Powered by Scopus

Exploring the AMOC Connectivity Between the RAPID and OSNAP Lines With a Model-Based Data Set

5Citations
N/AReaders
Get full text

Response of Subpolar North Atlantic Meridional Overturning Circulation to Variability in Surface Winds on Different Timescales

0Citations
N/AReaders
Get full text

Isopycnal Eddy Stirring Dominates Thermohaline Mixing in the Upper Subpolar North Atlantic

0Citations
N/AReaders
Get full text

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Cite

CITATION STYLE

APA

Tooth, O. J., Johnson, H. L., Wilson, C., & Evans, D. G. (2023). Seasonal overturning variability in the eastern North Atlantic subpolar gyre: a Lagrangian perspective. Ocean Science, 19(3), 769–791. https://doi.org/10.5194/os-19-769-2023

Readers' Seniority

Tooltip

Researcher 8

73%

PhD / Post grad / Masters / Doc 2

18%

Professor / Associate Prof. 1

9%

Readers' Discipline

Tooltip

Earth and Planetary Sciences 5

50%

Environmental Science 4

40%

Arts and Humanities 1

10%

Article Metrics

Tooltip
Mentions
Blog Mentions: 1
News Mentions: 1

Save time finding and organizing research with Mendeley

Sign up for free