A disposable ship launched free-floating air/water interface probe

During the investigation of the evaporation ducts over the ocean surface with reference to electromagnetic wave propagation characteristics, a need for near ocean surface measurements of temperature, humidity, pressure and water temperature were required. In response to this requirement the Applied Physics Laboratory, Johns Hopkins University developed several instruments for investigating the air/water interface. The disposable ship launched free-floating air/water interface probe (FAWIP-3) is the most recent instrument developed for making meteorological measurements within a few centimeters of the ocean surface. FAWIP-3 uses an Atmospheric Instrumentation Research, Inc. rocket radiosonde package to measure and telemeter the air temperature, humidity and pressure, and water temperature data back to a receiver aboard ship for data reduction and analysis. An innovative air baffling system is used to keep the sensors from salt water contamination and allows the air measurements to be made within two to five centimeters of the water surface. The FAWIP-3 data combined with shipboard meteorological data and low level rocketsonde profile data are used to calibrate and test evaporation duct refractivity models. This paper describes the FAWIP-3 instrument, its use and some of the data gathered during sea trials