Labrador Sea convection and circulation of low-salinity waters tracked by Seagliders, Argo and Altimetry

Hjalmar Hatun, Charlie Eriksen, and Peter Rhines

University of Washington,
Seattle, Washington, 98195
USA

We have observed with Seagliders, Argo floats and altimetry, the eddy-rich separation of the west Greenland boundary current in the Labrador Sea. This current provides buoyancy, at both deep and shallow levels, to mediate deep wintertime convection, and hence to mediate the creation of Labrador Sea Water. The inward advection of a buoyant, low-salinity surface layer also exerts strong control over the geographical distribution of late-winter mixed layer depth. The internal structure of intense, predominantly anticyclonic eddies embedded in the circulation, is probed at high resolution. Argo floats provide essential hydrographic fields ‘surrounding’ these intense events. A related issue, the 1990s decline of the altimetrically-observed subpolar gyre circulation and associated change in the Atlantic Water inflow from Atlantic to Nordic Seas will be touched upon.
Argo floats, Seagliders and satellite altimetery are strongly complementary in their sampling ability; we will discuss ways in which gliders can provide essential observations of ocean climate change.