I aim to understand the process of deep convection in the ocean. Near surface water is mixed to great depth at a few high latitude locations, thereby forming the deep and bottom masses of the ocean. This proposal has supported the development and deployment of neutrally buoyant floats in the Labrador Sea in the winters of 1997 and 1998 and the analysis of the resulting data. These floats provide detailed information on the processes and rates of deep convection. The density is matched to that of the ambient water by actively changing the float's volume and will stay matched, despite changes in pressure and temperature, though a combination of active control and a hull compressibility which is close to that of seawater.
High drag is achieved through a large circular cloth drogue attached to the float.
Overall, the floats worked very well, although there is room for improvement. Nearly 70 floats were launched, for 3 different ONR PI's and a cross-basin CTD section completed. A convectively mixed layer extending from the surface to about 700m in 1997 and 600m in 1998 is evident. Occasionally, floats penetrate well below the layer, some reaching depths exceeding 1 km. In 1998, some of the floats were seeded below the convective layer.