The IFF: The Isopycnal Float Fluorometer

Abstract

An isopycnal float has been developed which provides a description of water parcel motion and simultaneous measurements of chlorophyll a fluorescence, pressure and temperature along a chosen isopycnal surface. The device consists of a modified Swallow float with a ?compressee? to match the compressibility of the float to that of seawater, so that pressure-induced buoyancy changes are removed. The solid-state fluorometer, modified from a preexisting design, provides a measure of the temporal variability in chlorophyll a fluorescence. A pilot deployment of the float was made in September 1986 within a shelf water entrainment feature along the northern edge of the Gulf Stream near 37°N, 73°W. A primary application of the float is to measure upwelling velocities and the concurrent changes in the chlorophyll a fluorescence field.