A freely falling probe for small-scale temperature gradients

A light, simple, and fairly inexpensive hand-launched freely falling probe for measuring temperature microstructure was built. The circuitry operates under pressure in a Freon environment; low-power integrated circuits are used as components. The probe is assembled from plastic pipe and fittings and recovered with monofilament fishing line. Standard XBTs are adapted for use as the data link. Noise levels of 2 x 10^(-5) °C cm^(-1) were achieved in signals recorded during casts in the ocean and on inland waters. Portions of the water column can be rapidly resampled. The device can be operated from any size vessel