A high frequency chirp sonar to be deployed on the High Resolution Sampler (HRS II) and capable of sizing small zooplankton

A comprehensive marine particle analysis system has been developed by the University of South Florida, Department of Marine Science, to investigate the fine-scale distribution of zooplankton sized particles. This system, designated the High Resolution Sampler (HRS II), is a towed oceanographic platform that carries a number of independent optical and acoustical particle analysis systems designed to sample as broad a spectrum of the suspended particle population as possible (Sutton et al., this volume). A chirp sonar (3.5-6.5 MHz) system has been developed in collaboration with Florida Atlantic University to investigate the size and distribution of particles ranging from 250 /spl mu/m to 10 mm. This system is designed to augment and verify particle size and distribution information collected by Optical Plankton Counters (OPCs, Focal Technologies Inc.) also mounted on the HRS II. A chirp pulse sonar system has the unique ability to resolve individual targets in the time domain, which will allow for more accurate particle sizing and potentially target identification. The chirp sonar system can collect accurate measurements of particle size and distribution comparable to that of the OPC's on the HRS II and initial results are discussed.