|M.F. de Jong, A.S. Bower & H.H. Furey, Two years of observations of warm core anticyclones in the Labrador Sea and their seasonal cycle in heat and salt stratification, Journal of Physical Oceanography, in press, 2013|
Between 25 September 2007 and 28 September 2009 a heavily instrumented mooring was deployed in the Labrador Sea, offshore of the location where warm-core, anticyclonic Irminger Rings are formed. The two year time series offers insight into the vertical and horizontal structure of newly formed Irminger Rings and their heat and salt transport into the interior basin. Twelve Irminger Rings passed by the mooring in two years. Eleven of these had distinct properties, while one anticyclone likely passed the mooring twice. Eddy radii (11 to 35 km) were estimated using the dynamic height signal of the anticyclones (8 to 18 cm) together with the observed velocities. The anticyclones show a seasonal cycle in core properties when observed (1.9 °C in temperature, 0.07 in salinity at mid-depth) that has not been described before. The temperature and salinity are highest in fall and lowest in spring. Cold, fresh caps, suggested to be an important source of freshwater, were seen in spring but were almost non-existent in fall. The heat and freshwater contributions by the Irminger Rings show a large spread (12 to 108 MJ m-2 38 and -0.5 to -4.7 cm respectively) for two reasons. First, the large range of radii leads to large differences in transported volume. Second, the seasonal cycle leads to changes in heat and salt content per unit volume. This implies that estimates of heat and freshwater transport by eddies should take the distribution of eddy properties into account in order to accurately assess their contribution to the restratification.