A Generation of WOTAN Underwater Wind-Recording Instruments

The acronym WOTAN means Weather Observations Through Ambient Noise. Determining surface wind velocity by the measurement of underwater acoustic noise spectral intensity in the 5 to 15kHz region is now a proven technique in both deep and shallow water. WOTAN sensors are versatile and have been used as an add-on for all types of underwater instruments (especially those already employing an acoustic transducer) including satellite-reporting drifting buoys. This paper traces the development of WOTAN instruments during the last 13 years, and details the electronic circuitry involved. It compares the performance of the various forms and concludes with a description of a recent advanced version, the Sea Data model 661 WOTAN recorder.