Variability of the directly observed, middepth subpolar North Atlantic circulation. Issue 6 (16th March 2016)

• Record Type: Journal Article
• Authors: Palter, Jaime B.; Caron, Charles‐André; Law, Kara Lavender; Willis, Joshua K.; Trossman, David S.; Yashayaev, Igor M.; Gilbert, Denis
• Is Part Of: Geophysical research letters. Volume 43:Issue 6(2016)
• Page Start: 2700
• Page End: 2708
• Publication Date: 2016-03-16
• Subjects: ocean circulation -- Argo -- profiling floats -- decadal variability -- subpolar North Atlantic -- boundary currents; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2015GL067235
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Satellite views of the ocean have suggested a decline of the subpolar North Atlantic surface circulation during the 1990s and 2000s. This was a period of unprecedented observational capacity in the basin, thanks to the presence of many hundreds of profiling floats. We use more than 40, 000 subsurface displacements of these floats to characterize the circulation at 1000 m depth, and its evolution from 1997–2013. We show a statistically significant slowdown in the Labrador Sea boundary currents of −0.8 cm s −1 per decade (95% confidence interval of −1.4 to −0.15 cm s —1 per decade, a conservative estimate of the uncertainty). Otherwise, the middepth circulation field was largely stable. Our analysis of the location where the North Atlantic Current crosses the Mid‐Atlantic Ridge shows that profiling floats can reveal steering by bathymetric features, but do not reveal of decadal variability in the position where the current crosses the ridge. Key Points: Profiling float displacements show variability in North Atlantic circulation at 1 km depth Floats suggest slowdown of Labrador Sea boundary currents from 1997–2013, near limit of detectability Floats are funneled with the North Atlantic Current through fractures of Mid‐Atlantic Ridge