Research Document 2017/079

Physical oceanographic conditions on the Newfoundland and Labrador Shelf during 2016

By Colbourne, E., Holden, J., Snook, S., Han, G., Lewis, S., Senciall, D., Bailey, W., Higdon, J., and Chen, N.

Abstract

An overview of physical oceanographic conditions in the Newfoundland and Labrador Region during 2016 is presented as part of the Atlantic Zone Monitoring Program (AZMP). The North Atlantic Oscillation (NAO) Index, a key indicator of the direction and intensity of the winter wind field patterns over the Northwest Atlantic, remained in a positive phase during 2016; however, it was lower than in 2015. In addition, the spatial patterns of the associated atmospheric pressure fields resulted in a reduced arctic air outflow in the northwest Atlantic during the winter months. This resulted in higher than normal winter air temperatures in many areas. Sea ice extent, although above normal during March and April, was below normal overall during 2016. Annual sea-surface temperature trends on the northeast Newfoundland Shelf while showing an increase of about 1oC since the early 1980s were mostly below normal during 2016. The annual bottom (176 m) temperature/salinity at the inshore monitoring site (Station 27) was below normal at -0.7/-1.4 standard deviations (SD), respectively in 2016. Station 27 stratification was slightly below normal by -0.3 SD and the mixed-layer depth was deeper than normal by 0.5 SD. The cold-intermediate layer (CIL; volume of <0°C) during 2016 was below normal off southern Labrador (2J) but near normal on the northeast Newfoundland Shelf and Grand Bank (3KL). The volume of CIL water during the fall in the Northwest Atlantic Fisheries Organization (NAFO) Divisions 2J3KL from multi-species net-mounted CTD deployments was below normal. The spatially averaged spring bottom temperature in 3Ps was about 1°C (2 SD) above normal, a 33-year record, while in 3LNO it was about normal. The spatially averaged bottom temperature during the fall in 2J and 3K show an increasing trend since the early 1990s of about 1°C, reaching a peak of >2 SD above normal in 2011 and remaining above normal in 2016 by 0.5 and 0.3°C, respectively. A standardized composite climate index for the Northwest Atlantic derived from meteorological, ice and ocean temperature and salinity time series since 1950 reached a record low value in 1991. Since then it shows an increasing trend with mostly above normal values except for 2014 and 2015, the latter being the 7th lowest in 67 years and the lowest value since 1993. During 2016, the composite climate index returned to above normal conditions.

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