Exploiting In Situ Lidar To Retrieve Particle Distributions and Characteristics Of The Upper Ocean

Passive ocean color remote sensing has revolutionized our ability to quantify horizontal patterns of phytoplankton distributions across the ocean surface. Lidar technology, which has already proven its ability to produce high resolution models of bathymetry/topography, offers to provide critical insights into the vertical distribution of optical properties and suspended particles, significantly improving our ability to model biogeochemical processes in the upper ocean. We constructed an in-situ Lidar system for sub-surface deployment and measured laser backscattering profiles at stations in the coastal mid-Atlantic ranging from estuarine to oceanic conditions. The return signal was stronger at shallow depths and decayed faster as turbidity increased. System attenuation coefficients (K_sys) extracted from the Lidar signal were correlated with beam attenuation (c) and diffuse attenuation (K_d) coefficients determined simultaneously with profiling ac-9 and HyperPro instruments. We are now investigating the effect of particle composition on return signal depolarization with the addition of a second polarization channel and developing wavelength-tuning capability for the instrument. These results, in conjunction with data from bench-top laboratory experiments simulating various ocean environments support the proposition that full waveform, in-situ Lidar will be a relatively simple and powerful tool for measuring and monitoring optical properties and particle distributions in the upper ocean.