Development of a Bottom Following RAFOS float Mark

Development of a Bottom Following RAFOS float Mark Prater Dave Hebert URI

RAFOS Float There are two basic versions: Standard version: Isobaric (glass pipe has a much smaller compressibility and thermal expansion coefficient than seawater) Isopycnal version: A compressee (drop weight modified to contain a piston and spring) is used to match the float compressibility to that of the seawater in which the float would be deployed. f/h version - a volume change (vocha) added to allow the volume (density) of the float to be changed.

Temperature section along the Faroe Bank To follow the plume, we need a float that is neither isobaric and isopycnal but follows the bottom.

Prototype bottom-following RAFOS float The first attempt to keep the RAFOS float a predetermined height off the bottom using a passive system. A thin wire hung below the drop weight and dragged along the bottom. As the plume descends, the in-situ density increases. The RAFOS would normally stay at a constant pressure. However, as the float moves away from the bottom, some of the wire is lifted off the bottom and the float becomes heavier (denser).

Example of a deployment

Standard Mission • What should the float measure? • Should the profile throughout the boundary layer? • What products would best help constrain the models?