Impact of Irminger Rings on Deep Convection in the Labrador Sea

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The Labrador Sea, located in the northern North Atlantic Ocean, is a region where the ocean waters are consistently cooled by dry, cold winter winds coming from northern Canada. The cooled, and therefore dense "Labrador Sea Water" sinks and spreads widely throughout the North Atlantic and beyond, thereby "communicating" changes in the earth's climate to the deep ocean. A current carrying warmer waters flows into the Labrador Sea to balance this lost heat, the Irminger Current, but it is confined mainly to the periphery of the Labrador Sea. Occasionally, eddies containing a core of warm boundary current water, called Irminger Rings, break off and drift into the interior region of the Labrador Sea. Although the location of some of these eddies can be determined from satellite-borne instruments, there are very few actual in situ measurements of where and how they deposit their cargo of warm water into the open sea. Such information is needed to determine the impact of the rings on the heat balance of the Labrador Sea. New in situ measurements of Irminger Rings will be made using a combination of established and innovative technology. A deep-sea mooring with temperature, salinity and current sensors will be deployed in the path of young Irminger Rings for two years beginning in 2007 to observe their initial vertical and horizontal structure. It is anticipated that ~12 newly formed Irminger Rings will pass over the mooring site based on a census of eddies from satellite observations. Attached to the same mooring will be 12 profiling floats: one float will be released each time an eddy passes the mooring. Trapped in the eddy cores by the ring's strong swirling velocity, the floats will measure changes in their water properties for up to two years. These observations will be combined with satellite data and other in situ measurements to estimate the flux of heat into the interior Labrador Sea, and to verify results from numerical models.This research will contribute to the advancement of climate science as well as oceanography. The project involves collaboration with Canadian oceanographers and will contribute to international exchange of scientific ideas. Through a pilot program with the Perkins School for the Blind, we will provide an educational experience to a group of students typically underrepresented in the geosciences.