Tactical Oceanographic Measurement System (TOMS) Feasibility Report.

Transmission loss predictions were used to demonstrate the sensitivity of acoustic propagation to details of the environment. Significant modifications to predicted convergence zone location, width and intensity can result from a poor or incomplete knowledge of horizontal sound-speed gradients as small as 0.1 - 0.2 mskm. Similar sound speed gradients frequently occur in most oceans. Point sensor casts e.g. AXBTs cannot readily monitor the mesoscale variability responsible for these gradients. A new concept in tactical environmental monitoring -- the Tactical Oceanographic Measurement System TOMS--is based on an aircraft-deployed, mobile tomographic measurement. The hardware consists of a modified sonobuoy and an aircraft-based self-contained microprocessor for interpretation. TOMS would be completely compatible with current Navy airborne ASW systems and procedures. TOMS draws upon past experience with moored tomography to interpret the local approximately 400 km diameter circle acoustic environment from acoustic travel-times. TOMS emphasizes the upper ocean environment 1000 m depth where most oceanographic variability occurs. Analysis demonstrates good sensitivity to acoustically important oceanographic variability. The primary technical issue surrounding implementation of TOMS is that of buoy location. The freely drifting buoys can drift several kilometers during deployment of the array. Such large position uncertainties can complicate the interpretation process.