Backscatter Estimation Using Broadband Acoustic Doppler Current Profilers

Growing interest has developed in acoustic studies about the abundance and distributional patterns of the suspended matter, such as plankton and sediments, that act as sound scatterers for Broadband Acoustic Doppler Current Profiler measurements. Supported by careful calibration procedures, acoustic studies using vertical profiles of echo intensity from moored or vessel-mounted Broadband ADCPs can provide temporal and spatial information, that was previously difficult, if not impossible, to obtain, about the abundance of suspended matter. Moreover, combining these data with the simultaneous ADCP current profiles can lead to more informed, and potentially more insightful, interpretation of the distributional patterns of the plankton and suspended sediments. This interest in applying Broadband and Workhorse ADCPs for purposes that use the backscatter energy measurement motivated RDI to say “Yes, Virginia, you can use a Broadband or Workhorse ADCPs to measure absolute and/or relative backscatter coefficient (Sv) using BBADCP data.” This paper describes the calibration steps, performed at the factory and/or by the user that are necessary to estimate Sv. from ADCP data. It also describes the processing steps that are required after data are obtained from Broadband or Workhorse ADCP’s.