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Research Document - 2012/044

An assessment of the physical oceanographic environment on the Newfoundland and Labrador Shelf during 2011

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

Abstract

The North Atlantic Oscillation index, is a key indicator of climate conditions on the Newfoundland and Labrador Shelf, and after reaching a record low in 2010 it remained in the negative phase at 1.2 Standard Deviation (SD) below normal. As a result, arctic air outflow to the Northwest Atlantic remained weak in most areas in 2011. Annual air temperatures remained above normal at Labrador by 0.7 SD (0.9°C at Cartwright) and at Newfoundland by 0.6 SD (0.5°C at St. John’s) but declined significantly from the record highs of 2010. The annual sea ice extent on the NL Shelf remained below normal for the 16th consecutive year reaching a record low in 2011. As a result of these and other factors, local water temperatures on the Newfoundland and Labrador Shelf remained above normal, setting new record highs in some areas. Salinities on the NL Shelf were lower than normal throughout most of the 1990s, increased to above normal during most of the past decade but decreased to fresher-than-normal conditions in many areas from 2009-2011. At a standard monitoring site off eastern Newfoundland (Station 27), the depth-averaged annual water temperature increased to a record high in 2011 at 3 SD above the long-term mean. Annual surface temperatures at Station 27 were above normal by 0.6 SD (0.4°C) while bottom temperatures (176 m) were at a record high at 3.4 SD (1.3°C) above normal. The annual depth-averaged salinities at Station 27 were below normal for the 3rd consecutive year. The annual stratification index at Station 27 decreased to 2 SD below normal, the lowest since 1980. The area of the cold intermediate layer (CIL) water mass with temperatures <0°C on the eastern Newfoundland Shelf (Bonavista Section) during the summer of 2011 was at a record low value at 2 SD below normal, implying warm conditions, while off southern Labrador it was the 4th lowest at 1.5 SD below normal. On the Grand Bank the CIL area was the second lowest on record. The volume of CIL (<0°C) water on the NL shelf during the fall was below normal (4th lowest since 1980) for the 17th consecutive year. Average temperatures along sections off eastern Newfoundland and southern Labrador were above normal while salinities were generally below normal. All spring bottom temperature measurements in NAFO Divs. 3Ps and 3LNO during 2011 were above 0°C and up to 1°-2°C higher than normal. The gridded average bottom temperature across the 3Ps-3LNO region was at a record high. During the fall, bottom temperatures in 2J and 3K were also at a record high value, at 2 and 2.7 SD above normal, respectively, and in 3LNO they were 1.8 SD above normal. Generally, bottom temperatures were about 1°-2°C above normal in most regions, with very limited areas of the bottom covered by <0°C water. A composite climate index derived from 27 meteorological, ice and ocean temperature and salinity time series show a peak in 2006, a declining trend in 2007-09 and a sharp increase in 2010 and 2011 to the 2nd and 4th highest, respectively, indicating warmer than normal conditions throughout the region.

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