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Research Document - 2011/094

Meteorological, Sea Ice and Physical Oceanographic Conditions on the Scotian Shelf and in the Gulf of Maine during 2009 and 2010

By D. Hebert, R. Pettipas, and B. Petrie

Abstract

In 2009, the North Atlantic Oscillation (NAO) index was positive (+1.5 mb, +0.2 SD) and slightly lower than its 2008 value (+4.3 mb, +0.5 SD); in 2010, the NAO index was at its lowest value in the entire record analyzed, -25.1 mb, 2.9 SD below normal. Mean annual air temperatures were from 0.5°C below to 0.2°C above normal in 2009; in 2010, annual air temperatures were 1.1 to 1.7°C above normal making this year the warmest since 1900. In 2009, the average January to April ice volume on the Scotian Shelf was the 7th highest in the 42 year series, whereas, the volume during 2010 was the second lowest and not significantly different from the lowest volume on record. Positive sea surface temperatures (SST) anomalies prevailed throughout the region during 2009 and 2010 with representative values of about +0.2 and 0.4°C (+0.4 and 0.6 SD). Long-term coastal monitoring sites at St. Andrews and Halifax recorded weak annual SST anomalies of 0.2°C and -0.3°C in 2009, and stronger positive anomalies, 1.0°C and 0.4°C in 2010. Across the region annual temperature anomalies were mixed in 2009:  -0.5°C for Cabot Strait 200-300 m, +0.3°C for Misaine Bank 100 m, -1.3°C for Emerald Basin 250 m, +1.1°C for Lurcher Shoals 50 m, and -0.1°C for Georges Basin 200 m. Anomalies were generally positive throughout the region in 2010: +0.3°C for Cabot Strait 200-300 m, +0.4°C for Misaine Bank 100 m, +0.6°C for Emerald Basin 250 m, +0.1°C for Lurcher Shoals 50 m, and +1°C for Georges Basin 200 m. Bottom temperature anomalies in NAFO areas 4VWX ranged from -0.1°C to +0.2°C in 2009, +0.2°C to +0.6°C in 2010. Stratification was near normal in 2009 but exceptionally strong, the 3rd highest in the 64 year record, in 2010. A composite index consisting of ocean temperatures from surface to bottom across the region indicated that 2009 was the 13th warmest of 41 years, with a normalized anomaly of +0.4 relative to the 1981-2010 period;  2010 was an exceptional year, the 4th warmest in the 41 year record with a normalized anomaly of +2.4.

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