Acoustic Measurements of Tiny Optically Active Bubbles in the Upper Ocean

In this project, which is closely linked to a separate project where the goal is to measure wave induced bubble clouds and their effect on radiance in the upper ocean (N000140710754), we intend to address the disturbing fact that despite the fundamental importance of optical backscatter in the ocean it is still not possible to explain more than 5 to 10 percent of the particulate backscattering in the ocean based on known constituents even during periods with no active wave breaking (Terrill & Lewis, 2004). One hypothesis is that very small bubbles that have been stabilized by surfactants may be responsible for part of the “missing” backscatter. The long-term goal of this project is to develop an acoustic tool to test this hypothesis and if these small bubbles are present, to determine their concentration and size distribution.