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Research Document - 2013/052

An assessment of the physical oceanographic environment on the Newfoundland and Labrador Shelf during 2012

By E. Colbourne, J. Craig, C. Fitzpatrick, D. Senciall, P. Stead, and W. Bailey

Abstract

A key indicator of climate conditions on the Newfoundland and Labrador (NL) Shelf, the North Atlantic Oscillation (NAO) index, increased to 1.3 Standard Deviations (SD) above normal in 2012, the highest since 1989. As a result, arctic air outflow to the Northwest Atlantic during the winter increased over the previous year causing a significant decrease in winter air temperatures over much of the Labrador Sea area. Annually however, air temperatures remained above the long-term mean at Labrador by 1.4 SD (1.8 °C at Cartwright) and Newfoundland by 2.3 SD (1.9 °C at St. John’s, a record high). The annual sea ice extent on the NL Shelf remained below normal (0.7 SD) for the 17th consecutive year, but increased by 1 SD over the record low in 2011. As a result of these and other factors, local water temperatures on the NL Shelf remained above normal in most areas but decreased significantly over 2011 values. Sea surface temperatures attained record highs (>2 SD) in some areas of the Grand Banks. At a standard monitoring site off eastern Newfoundland (Station 27), the depth-averaged annual water temperature decreased to 1 SD (0.4 °C) above normal from the record high of 3 SD (1 °C) in 2011. Annual surface temperatures at Station 27 increased to 1.5 SD (1 °C, 2nd highest on record) above normal while bottom temperatures (176 m) decreased to 1.1 SD (0.4 °C), down from the record high of 3.4 SD (1.3 °C) in 2011. The annual depth-averaged salinities at Station 27 were near the long-term average. The area of the cold intermediate layer (CIL) water mass with temperatures <0°C on the eastern Newfoundland and southern Labrador Shelf during 2012 was about 0.5 SD below normal compared to the record low value of 2 SD below normal in 2011, implying a continuation of less cold shelf water than normal. Spring bottom temperatures in NAFO Divs. 3Ps and 3LNO during 2012 were above normal by an average of about 1 °C, a moderate decrease over 2011 conditions. During the fall, bottom temperatures in 2J, 3K and 3LNO decreased from 2, 2.7 and 1.8 SD above normal in 2011 to 1.1, 1.2 and 0.2 SD above normal in 2012 respectively, a significant decrease. The volume of CIL (<0 °C) water on the NL shelf during the fall was close to normal. A composite climate index derived from 27 meteorological, ice and ocean temperature and salinity time series declined from 2nd and 4th highest in 2010 and 2011 to the 8th highest in the 63 year time series in 2012.

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