Development of a Bottom Following RAFOS float

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Development of a Bottom Following RAFOS float

• Mark Prater
• Dave Hebert
• URI

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

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