Research Document 2018/016
Meteorological, Sea Ice and Physical Oceanographic Conditions on the Scotian Shelf and in the Gulf of Maine during 2016
By Hebert, D., Pettipas, R., Brickman, D., and Dever, M.
Abstract
In 2016, the North Atlantic Oscillation index was above the 1981-2010 mean (+4.6 mb, +0.5 SD [standard deviation]) but significantly small than in 2015 which was the largest value in the 122 year record. Mean annual air temperature anomalies were positive at all sites examined with values ranging from +0.8°C (+0.9 SD) to +1.2°C (+1.9 SD) above the climatology. Positive satellite-based sea surface temperature (SST) annual anomalies prevailed throughout the region with values ranging from +0.5°C (+0.5 SD) at Cabot Strait to +1.7°C (+1.6 SD) in the Bay of Fundy. After above average conditions in 2015, sea ice coverage returned to conditions found in the 2010-2013 period which had extremely low coverage and volume. Long-term coastal monitoring sites at St. Andrews (New Brunswick) and Halifax (Nova Scotia) recorded annual SST anomalies of +1.4°C (+2.5 SD) and +1.0°C (+1.5 SD), respectively, in 2016. At other selected sites across the region, annual water temperature anomalies were positive in 2016: +1.3°C (+3.6 SD) for Cabot Strait at 200-300 m depth range (the largest anomaly); +1.2°C (+1.9 SD) for Misaine Bank at 100 m; +1.6°C (+1.9 SD) for Emerald Basin at 250 m (a record high); +1.0°C (+1.2 SD) for Lurcher Shoals at 50 m; and +1.4°C (+2.6 SD) for Georges Basin at 200 m (a record high). Bottom temperature anomalies in Northwest Atlantic Fisheries Organization (NAFO) Divisions 4VWX were all positive in 2016 ranging from +0.9°C (+2.1 SD) in Division 4Vn to +1.9°C (+2.6 SD) in Division 4X. Average stratification on the Scotian Shelf increased after several years of weakening but was less than 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 2016 was the second warmest of 47 years (2012 was the warmest) of observations, with an averaged normalized anomaly of +2.1 SD relative to the 1981-2010 period.
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