The Annual ICES Ocean Climate Status Summary 2001/2002
The NAO: The North Atlantic Oscillation (NAO) index has been slowly recovering to positive values since the extreme negative value of 1996. However, during the winter preceding 2001 it again became negative. The response seen throughout the ICES area to the 1996 switch of the NAO has not been observed in 2001, probably due to a different pattern of sea level pressure over the North Atlantic. In 2001 the pattern exhibited a large weak positive anomaly stretching from northern Scandinavia to Newfoundland.
Area 1: Ocean temperatures off West Greenland showed considerable warming during the summer and autumn of 2001. This warming was similar to that observed during the 1960s. Anomalously high salinities were observed in the off-slope surface waters during the autumn.
Area 2: Annual mean air temperatures over all areas of the Northwest Atlantic were above normal during 2001, but decreased compared to the records set in 1999. The amount of sea ice on the eastern Canadian continental shelf continued to be below normal for the fourth consecutive year. Except for southern areas of the Newfoundland and the northern Scotian shelves, ocean temperatures were above normal, continuing the warm trend established in the late 1990s.
Area 2a: Surface waters over the entire Scotian Shelf have been warmer and fresher than average during the past several years, including 2001. The higher temperatures are due to the warmer atmospheric conditions and the low salinities have been related to upstream influences off Newfoundland.
Area 2b: The upper layers of the Labrador Sea were observed to be warmer, saltier, and less dense in the summer of 2001 compared with conditions in 2000. These changes seem to be due largely to the inflow of Atlantic waters. There is no evidence that convective overturning during the winter of 2000–2001 reached depths greater than 400–500 m.
Area 3: In Icelandic waters there were relatively high temperatures and salinities, as there have been for the previous 3 – 4 years following the very cold years of 1995 and 1996. However, 2001 temperatures and salinities were slightly cooler and fresher than in 1999 and 2000.
Area 4: The Bay of Biscay continued to show a progressive decrease in salinity, which began in 1999. Averaged upper water layer temperature was low compared to values obtained during the last decade, whereas yearly averaged air temperature remained at the same level as the preceding three years.
Area 5: The Rockall Trough began to cool and freshen slightly during 2001, although both temperature and salinity remained high compared to the long-term mean, with values similar to previous peaks in the early 1980s.
Area 6: The temperature and salinity of Atlantic water passing through the Faroe Bank Channel and across the Iceland-Faroe Ridge have remained fairly constant since 1997.
Area 7: With respect to the last four decades, Atlantic waters in the Faroe Shetland Channel are generally warming and becoming more saline. However, there was little change between 2000 and 2001.
Areas 8 and 9: In terms of the surface temperatures of the North Sea, 2001 was generally warmer than normal. The summer of 2001 exhibited a reduced influence of Atlantic water in the northern North Sea and also in the Southern Bight. The low salinities in the southern North Sea suggest stronger than normal run-off from the continental rivers. The Baltic outflow south-west of Norway in summer 2001 was stronger than normal.
Area 9b: In the Baltic, surface waters generally became fresher due to high freshwater inputs following a wet winter. Surface temperatures were warmer than average. There were deep-water inflows into the Baltic Sea from the North Sea in the autumn of 2001.
Area 10: In the Norwegian Sea a long term warming trend continued, and in 2001 the area occupied by Atlantic water was the greatest since 1991.
Area 11: The Barents Sea was warmer than average during 2001, but the temperature gradually decreased throughout the year from nearly 1°C to just 0.1°C above average. As a result the area remains comparatively ice-free.
Area 12: Conditions in the Greenland Sea were generally warmer and more saline in 2001 compared to 2000. Although on average winter convection went down to 800 m, in small isolated patches it reached 2500 m.