North Atlantic extratropical and subpolar gyre variability during the last 120 years: a gridded dataset of surface temperature, salinity, and density. Part 1: dataset validation and RMS variability
We present a binned annual product (BINS) of sea surface temperature (SST), sea surface salinity (SSS), and sea surface density (SSD) observations for 1896–2015 of the subpolar North Atlantic between 40° N and 70° N, mostly excluding the shelf areas. The product of bin averages over spatial scales on the order of 200 to 500 km, reproducing most of the interannual variability in different time series covering at least the last three decades or of the along-track ship monitoring. Comparisons with other SSS and SST gridded products available since 1950 suggest that BINS captures the large decadal to multidecadal variability. Comparison with the HadSST3 SST product since 1896 also indicates that the decadal and multidecadal variability is usually well-reproduced, with small differences in long-term trends or in areas with marginal data coverage in either of the two products. Outside of the Labrador Sea and Greenland margins, interannual variability is rather similar in different seasons. Variability at periods longer than 15 years is a large part of the total interannual variability, both for SST and SSS, except possibly in the south-western part of the domain. Variability in SST and SSS increases towards the west, with the contribution of salinity variability to density dominating that of temperature in the western Atlantic, except close to the Gulf Stream and North Atlantic Current in the southwest area. Weaker variability and larger relative temperature contributions to density changes are found in the eastern part of the gyre and south of Iceland.
KeywordsSea surface temperature Sea surface salinity Surface density North Atlantic Decadal variability
Comments by two reviewers and by Semyon Grodsky were appreciated. The BINS product is available at https://doi.org/10.6096/TSD-BINS-NASPG.
This is a contribution to the French SSS observation service, which is supported by French agencies INSU/CNRS, IRD, CNES, and IPEV, as well as from SOERE CTDO2. The Rockall Trough time series were provided with support from the UK Natural Environment Research Council (Extended Ellett Line Program, National Capability). The station time series south of Iceland were provided with Icelandic support. The annual oceanographic monitoring of the Labrador Sea was initiated as a Canadian contribution to the World Ocean Circulation Experiment in 1990 and is presently conducted as a core component of the Atlantic Zone Off-Shelf Monitoring Program (AZOMP) run by the Bedford Institute of Oceanography of Fisheries and Oceans Canada. The International Argo Program is part of the Global Ocean Observing System (Argo 2000). Argo data are available from the Coriolis Global Data Center, Institut français de recherche pour l’exploitation de la mer (Ifremer). The HadSST3 and EN4 data were provided by the Met Office Hadley Center, and the ISHII data were provided by the NCAR Research Data Archive. A.R.F. was supported by SOERE CTDO2 and the ERC funded project TITAN (EC-320691). L.C. acknowledges support from the Swedish National Space Board (SNSB; Dnr 133/17).
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