The ICES Working Group on Ocean Hydrography met via video conference on March 26, 2020 to review oceanographic conditions in the North Atlantic in 2019. The joint analysis of the existing hydrographic timeseries provided the following highlights.
Highlights for the North Atlantic 2019
The fresh anomaly that has persisted within the eastern North Atlantic sector in recent years has weakened in the subpolar gyre, while strengthening in the subtropical region to the south and Arctic regions to the north.
A large-scale latitudinal pattern of warming-cooling-warming of the subtropical, subpolar ocean and Nordic Seas surface layers (0-100m), prevailing since 2002, reversed to one of cooling-warming-cooling in the most recent years (2018-2019) as evidenced by the array of Argo profiling floats.
Bottom ocean temperatures in the western North Atlantic were warmer than normal along the Northeast US Shelves, including record highs in the deep basins of the central Scotian Shelf and in the deep channels of the Gulf of St. Lawrence. Surface temperatures were above-normal on the Labrador Shelf, near normal to above normal on the Newfoundland Shelf, Western Scotian Shelf and Northeast US Shelves, and below normal in the Gulf of St. Lawrence and on the Eastern Scotian Shelf.
The eastern subpolar North Atlantic remains fresh in 2019, but is recovering from extreme minimum values observed in 2016-17. Surface waters were anomalously warm during summer throughout the region.
Widespread freshening continued in the northeastern Subtropical Gyre, including in the Bay of Biscay, West Iberia, Gulf of Cadiz and Canaries regions. This was coupled with continued cooling specially in the southern regions while temperature stabilized above 300 m in Biscay and Western Iberia. The upwelling system extending from the Gulf of Cadiz to the Canaries was the coldest and freshest observed since 2000.
While still warmer than average, Atlantic Water trended cooler and fresher along its route through the Norwegian Sea and into the Barents Sea and Fram Strait. In contrast, deep waters in the Greenland Sea trended warmer and saltier.
Conditions in the North Sea and Baltic Sea were generally warm. Fresh conditions were observed in the North Sea, due to fresher inflows from the North Atlantic, and in eastern Baltic. Severe hypoxic conditions were prevalent in the Baltic Sea, similar to the situation in 2018.
Highlights for the North Atlantic atmosphere in winter 2018/2019
The NAO index remained positive for a 6th successive winter. The index was strongest since 2015, but the associated pattern of sea level pressure was most evident in the east of the region.
Air temperatures were relatively warm across Europe, the Nordic seas, and the Labrador Sea.
Colder-than-normal winter air temperatures were limited to a region stretching from Nova Scotia to east of Flemish Cap.
Wind speeds across the region in winter 2018/19 were generally lower than average, particularly east of Newfoundland, also from south of Cape Farewell across to the northern North Sea, and in a band stretching across the Nordic seas from Scoresbysund in Greenland to the North Cape of Norway.
Outlook for the North Atlantic region in 2019/2020
The NAO index for winter 2019/2020 is likely more strongly positive than the last winter with more typical NAO sea level pressure anomaly pattern extending across the region.
A region from the west of Ireland across the UK, North Sea and southern Scandinavia will have experienced particularly strong south westerly winds through December-February.
Experimental seasonal forecasts predict that summer 2020 surface temperatures are likely to be warmer than average across the region, but that the subpolar gyre to the west of Ireland and Iceland and southeast of Cape Farewell are more likely to be near average than other areas.
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