North Atlantic subpolar gyre along predetermined ship tracks since 1993: a monthly data set of surface temperature, salinity, and density

Gilles Reverdin,Lars Heilmann,Tanguy Szekely,Andrew R Friedman,Gustavo Goni,Leon Chafik,Francis Bringas,Gael Alory,Denis Diverres,Hedinn Valdimarsson

doi:10.5194/essd-10-1403-2018

Abstract

Abstract. We present a binned product of sea surface temperature, sea surface salinity, and sea surface density data in the North Atlantic subpolar gyre from 1993 to 2017 that resolves seasonal variability along specific ship routes (https://doi.org/10.6096/SSS-BIN-NASG). The characteristics of this product are described and validated through comparisons to other monthly products. Data presented in this work were collected in regions crossed by two predetermined ship transects, between Denmark and western Greenland (AX01) and between Iceland, Newfoundland, and the northeastern USA (AX02). The data were binned along a selected usable transect. The analysis and the strong correlation between successive seasons indicate that in large parts of the subpolar gyre, the binning approach is robust and resolves the seasonal timescales, in particular after 1997 and in regions away from the continental shelf. Prior to 2002, there was no winter sampling over the West Greenland Shelf. Variability in sea surface salinity increases towards Newfoundland south of 54∘ N, as well as in the western Iceland Basin along 59∘ N. Variability in sea surface temperature presents less spatial structure with an increase westward and towards Newfoundland. The contribution of temperature variability to density dominates in the eastern part of the gyre, whereas the contribution of salinity variability dominates in the southwestern part along AX02.

Highlights

The North Atlantic subpolar gyre (NASPG) has been extensively studied and observed during the last 25 years
For each month of the calendar year, we evaluate the rootmean square standard deviation of interannual variability of the anomaly time series
The validated data presented here are able to characterize the seasonal variability of surface temperature and salinity along two transects crossing the North Atlantic subpolar gyre from July 1993 to December 2017

Summary

Introduction

The North Atlantic subpolar gyre (NASPG) has been extensively studied and observed during the last 25 years This time span presents the succession of a cold period in the early 1990s associated with strong North Atlantic Oscillation (NAO) forcing, a warmer period from 2000 to 2009, followed by a cooling (Robson et al, 2016), and strong NAO forcing in 2014 and 2015 (Josey et al, 2017). There has been extensive variability in mode waters and their thickness in the northern and northeastern subpolar gyre, such as the Reykjanes mode water (Thierry et al, 2008) or the Rockall Trough mode water (Holliday et al, 2015) The changes in these subsurface water properties and distributions drive ocean circulation and in particular play a likely role in the Atlantic Meridional Overturning Circulation (AMOC) variability (Robson et al, 2016; Rahmstorf et al, 2015). The surface layer provides the link between the ocean interior and the atmosphere

Methods

Results

Conclusion