Naval Res. Lab., Washington, DC 20375-5000
Average low-frequency under-ice reflection coefficients were estimated from long-range Arctic data (FRAM IV) by matched-field processing techniques (Livingston and Diachok, 1989). The method is a straightforward application of optimization using multiple thresholds over a finite set of parameter values, and will be described and discussed with regard to its advantages, disadvantages, and appropriate problem settings. The performance of this method in problems of determining sound-speed structure, optimum replica mode number, and several other types of parameters will be analyzed. In particular, the possible application of the method to the determination of bottom reflection coefficients is considered.