Using acoustic modeling to develop a hybrid H-ADCP configuration

The Port Everglades Shipping Channel (PESC) in Ft. Lauderdale, Florida is thought to be a pathway by which anthropogenic nutrients and pathogens reach the coastal ocean from inland waters. To quantify this, a flow measurement system was installed in the PESC. In planning this measurement system, conventional vertical and horizontal ADCP configurations were considered but found to be unsuitable for differing reasons. This motivated the development of a hybrid deployment configuration. A Teledyne-RDI 300 kHz H-ADCP was deployed near the surface with an 8.5 degree downward tilt so that measurement cells nearest to the instrument would record data from the upper water column while cells further from the instrument would record data from deeper depths. The PESC is often times vertically stratified and it was realized that this stratification could affect the data received from a system deployed in this manner. To estimate these effects, sound speed profiles taken in the PESC were used as input to an acoustic propagation model. This model simulated the acoustic paths from the instrument deployed at different angles. Analysis of these simulations enabled the selection of the optimal angle for deployment that allowed for the maximum profiling range while minimizing the effects of stratification on the acoustic path.