Research Document - 2015/040
Meteorological, Sea Ice and Physical Oceanographic Conditions on the Scotian Shelf and in the Gulf of Maine during 2014
By D. Hebert, R. Pettipas, D. Brickman, and M. Dever
In 2014, the North Atlantic Oscillation index was above the 1981-2010 mean (+11.5 mb, +1.3 SD [standard deviation]) after last year’s slightly negative value and nearly as large as the index in 2012, which was the fourth largest value. Mean annual air temperature anomalies were positive at all sites except Boston at -0.3oC (-0.4 SD) with values ranging from slight positive at Saint John, New Brunswick to +1.2oC (+1.7 SD) at Sable Island, Nova Scotia. Sea ice coverage on the Scotian Shelf in 2014 was slightly above the 1981-2010 average unlike the four previous years, which had extremely low coverage and volume. Positive satellite-based sea surface temperature (SST) anomalies prevailed throughout the region in 2014, with annual values ranging from +0.5 to +1.8oC (+0.4 to +1.5 SD) above the 1981-2010 mean values. Long-term coastal monitoring sites at St. Andrews (New Brunswick) and Halifax (Nova Scotia) recorded annual SST anomalies of +0.6oC (+1.0 SD) and +0.1oC (+0.2 SD), respectively, in 2014. At selected sites across the region, annual water temperature anomalies were positive in 2014: +0.9oC (+2.7 SD) for Cabot Strait 200-300 m depth range (the second largest anomaly; 2012 was the largest); +0.6oC (+1.0 SD) for Misaine Bank at 100 m; +1.4oC (+1.7 SD) for Emerald Basin at 250 m; +1.7oC (+2.2 SD) for Lurcher Shoals at 50 m; and +1.2oC (+2.3 SD) for Georges Basin at 200 m (the warmest year was 2013). Bottom temperature anomalies in Northwest Atlantic Fisheries Organization (NAFO) Divisions 4VWX were all positive in 2014 ranging from +1.1oC (+1.6 SD) in NAFO Division 4Vs to +2.0oC (+2.6 SD) in NAFO Division 4W. Average stratification on the Scotian Shelf weakened compared to 2013 and was nearly equal to the 1981-2010 mean value. Since 1948, the stratification has slowly been increasing on the Scotian Shelf due mainly to half freshening and half warming of the surface waters. A composite index, consisting of 18 ocean temperature time series from surface to bottom across the region, indicated that 2014 was the second warmest of 45 years (2012 was the warmest), with an averaged normalized anomaly of +1.6 SD relative to the 1981-2010 period.
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