Research Document - 2014/094

Physical oceanographic conditions on the Newfoundland and Labrador Shelf during 2013

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

Abstract

A key indicator of ocean climate conditions on the Newfoundland and Labrador (NL) Shelf, the North Atlantic Oscillation (NAO) index, returned to a weak negative phase in 2013 and as a result arctic air outflow to the Northwest Atlantic during the winter decreased over the previous year. This appears to have resulted in an increase in winter air temperatures over much of the Labrador Sea area causing a continuation of less sea-ice than normal on the NL Shelf. Annually however, air temperatures decreased over 2012 but remained above the long-term mean in southern Labrador by 0.5 SD (0.7°C at Cartwright) and Newfoundland by 0.8 SD (0.7°C at St. John’s). The annual sea ice extent on the NL Shelf remained below normal (-1.4 SD) for the 18th consecutive year, a decrease of 0.5 SD over 2012. As a result of these and other factors, local water temperatures remained above normal in most areas in 2013 but showed a decrease over 2011-2012 values. Average sea surface temperatures on the NL Shelf decreased from 1.6 SD above normal in 2012 to about 0.4 SD above normal in 2013 and near shore at Station 27 they were 1.1OC (1.6 SD) above normal, similar to 2012. Bottom temperatures at Station 27 were 1 SD (0.4°C) above normal, nearly identical to 2012 values. Spring bottom temperatures in NAFO Div. 3P ranged from 0.4 to 1.1 SD above normal in 2013 down from near +2 SD in 2011 and in 3LNO they ranged from 0.8 to 1.3 SD above normal, a moderate decrease over the previous two years. 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 and to 0.8, 0.5 and 0.1 above normal in 2013, respectively, a significant decrease in the past 2 years. The area of the cold intermediate layer (CIL) water mass with temperatures <0°C along standard AZMP sections on the NL Shelf during the spring, summer and fall were below normal ranging from 0.7 to 1.5, 0.5 to 1.4 and 0.3 to 0.9 SD, respectively, implying a continuation of less cold shelf water than normal. In general, most environmental indices show a continuation of a warmer than normal trend throughout the area. During the past 2 years however, temperatures have decreased from the record warm conditions of 2011. A composite climate index derived from 27 meteorological, ice and ocean temperature and salinity time series declined from 8th highest in 2012 to the 18th highest in the 64 year time series in 2013.

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