Research Document - 2014/046

Oceanographic and Environmental Conditions in the Labrador Sea during 2012

By I. Yashayaev, E.J.H. Head, K. Azetsu-Scott, Z. Wang, W.K.W. Li, B.J.W. Greenan, J. Anning, and S. Punshon

Abstract

Following three years of negative state of North Atlantic Oscillation (NAO) with the 2009-10 value being a record low in the entire time series, the NAO index for the December-January-February (DJF) period of 2011-12 was strongly positive, close to the level in early 1990s, a period which experienced the highest NAO index values in the last two decades. The National Centers for Environmental Prediction reanalysis of surface air temperature also indicated below normal conditions with an anomaly of 0 to -2°C in the Labrador Sea during the winter period; for the summer period, the anomaly was positive with a range of approximately 1-3°C; the fall period was characterized by a strong positive anomaly of 4-6°C in the Baffin Bay/Davis Strait area north of the Labrador Sea. Sea surface temperature anomalies in the Labrador Sea followed the pattern observed in the air temperature being negative (0 to -1°C) in the winter and positive (1 to 3°C) in the summer. The Labrador Shelf ice anomaly was below normal in January-February 2012 (reference period: 1979-2000). In March 2012, sea ice conditions on the northern Labrador Sea/Davis Strait area were well above normal. Winter time convection in 2012 reached to 1400 m, which is significantly deeper than the 800 m seen in 2011, although still less than the 1600 m of 2008. The 1000-1500 m layer has been warming since 2002 with resets in 2008 and 2012 only. The increasing trend of the total inorganic carbon and decreasing trend of pH continue. For the year of 2012 as a whole, chlorophyll a estimated from two-week ocean colour composite images was below normal on the Labrador and Greenland shelves, but normal in the central Labrador Basin. The abundance of Calanus finmarchicus was near (above) normal on the Labrador (Greenland) Shelf.

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