Mid-range Acoustic Transmission Loss: Near Shore Measurements Under Varying Atmospheric and Terrain Conditions

These proposed field studies will provide a comprehensive data set of acoustic transmission loss measurements in a variety of atmospheric conditions. These pitch-catch style measurements will take place on multiple days at several sites around eastern North Carolina at ranges up to approximately 3 kilometers. The acoustic measurements have concurrent meteorological information gathered from both traditional stationary monitoring as well as a UAV-mounted sensor that records temperature, pressure, humidity, and location information at several locations along the propagation path and up to 100 meter altitude. This data set serves to bolster the work in progress by the investigator under ONR Award N00014-17-1-2213. This data set will be collected using an existing transmission loss measurement system. The specific equipment includes a set of three multi-channel GPS-synchronized acoustic measurement modules. Each module is instrumented with 7 microphones on a 7 meter mast. A LIDAR system that represents a substantial improvement in atmospheric measurements has been requested via DURIP. The ultimate aim of the ongoing overall research thread is to understand ship detectability given current atmospheric and weather conditions. The specific aim of this proposed effort is to provide a canonical data set of acoustic transmission loss and concurrent atmospheric conditions that (1) is of high spatiotemporal resolution, (2) is in physical locations of Naval relevance, and (3) spans a wide range of meteorological conditions. Thisdata set is a necessary tool that will enable effective evaluation of candidate numerical models.