Evaluation of data measured by acoustic profilers on the Southeast Brazilian Continental Slope

This paper discusses a preliminary evaluation of the data measured by lagrangian acoustic profilers deployed on the southeast Brazilian Continental Slope. These profilers are drifting on an extensive area of the western Atlantic Ocean gathering and internally processing acoustic signals acquired from five distinct water levels, centered about 50m, 200m, 500m, 750m, and 950m below sea surface. The processing consists in calculating some acoustic parameters, such as sound pressure levels (SPL) and third-octave spectra for each measured acoustic window. These acoustic parameters are sent via satellite each time the profiler reaches the sea surface, along with the profiler GPS position. Data acquisition covers a period from November 2015 to December 2016, when 50 lagrangian profilers were launched. Since raw acoustic signals are not stored in the equipment or sent by satellite, we developed a statistic using the spectral parameters to evaluate the quality of those transmitted parameters. In our approach, an outlier is detected and is considered a suspect parameter if it falls off some distance from the mean value of the distribution of that parameter, considering all available values. A brief presentation of measured data is made and results are discussed based on experience with the acoustic soundscape of this region.