https://cdn.earthdata.nasa.gov/conduit/upload/5182/KeywordsCommunityGuide_Baseline_v1_SIGNED_FINAL.pdf 23.6 2026-03-19T10:41:57.720Z https://gcmd.earthdata.nasa.gov/KeywordViewer/scheme/instruments/ca8de50f-b795-42b7-9301-8baffe2de0f3 ADCP The Acoustic Doppler Current Profiler (ADCP) measures currentsbeneath a ship while underway. Sound signals sent from themoving ship bounce back to receivers aboard the ship. Thisprovides a profile of water movement relative to theship-precise modern navigation, allowing the ship's motion to besubtracted from the data. These devices are also used onmoorings and profilers and, along with acoustic backscattering,measure animal biomass. Particles in the path of the soundwaves, mostly plankton, reflect a small part of the sound energyback toward receivers, allowing researchers to make remoteestimates of the sizes and numbers of animals present in thewater column. Before the 1970's, the most technologicallyadvanced instrument used to measure water velocity was known asa Doppler speed log. This evolved into the first commercialADCP, produced in the mid-1970's, which used averaging. Later inthe 1970's, the first vessel-mounted ADCP was developed tomeasure water velocity more accurately and to allow measurementin range cells over a depth profile.As instruments evolved, so did new techniques in Doppler signalprocessing. Initially, Doppler speed logs used simple analogsignal processing methods, which are still used in somecommercial speed logs today. However, the first ADCPsincorporated analog-to-digital signal conversion over a narrowcommunication bandwidth. Around 1990, this technique wasdeveloped into broadband signal processing. Since then,broadband ADCPs have been able to generate very accurate,real-time velocity measurements.Additional information available at'http://www.whoi.edu/instruments/viewInstrument.do?id=819'