The Skin-Layer Ocean Heat Flux Instrument (SOHFI). Part I: Design and laboratory characterization

An untended instrument to measure ocean surface heat flux has been develope d for use in support of field experiments and the investigation of heat flu x parameterization techniques. The sensing component of the Skin-Layer Ocea n Heat Flux Instrument (SOHFI) consists of two simple thermopile heat flux sensors suspended by a fiberglass mesh mounted inside a ring-shaped surface float. These sensors make direct measurements within the conduction layer, where they are held in place by a balance between surface tension and floa t buoyancy. The two sensors are designed with differing solar absorption pr operties so that surface heat flux can be distinguished from direct solar i rradiance. Under laboratory conditions, the SOHFI measurements agree well w ith calorimetric measurements (generally to within 10%). Performance in fre shwater and ocean environments is discussed in a companion paper.