A SOLVER FOR ESTIMATING RANGE-RESOLVED BEAM ATTENUATION COEFFICIENT FROM IN-WATER LIDAR WAVEFORMS

The beam attenuation coefficient (c) is a critical optical property for ecosystem models and military operations. Time-resolved waveforms produced by remotely located LiDAR (Light detection and ranging) backscattering systems carry high spatial resolution information relating to c. Due to multiple scattering, beam spreading and energy decay with range, the LiDAR attenuation coefficient (K-sys) tends to under-estimate the true c value at greater optical thicknesses. An inversion technique to estimate c as a function of range was developed based on empirical relationships between the arithmetic average of range-resolved backscattering values (beta m) and changes on c - K-sys using backscattering measurements at a wavelength of 532 nm and derived from a scanning FSUIL LiDAR instrument (Fine Structure Underwater Imaging LiDAR). Lab models differed from parameterizations derived from field measurements obtained in coastal waters of the Gulf of Mexico as tank experiments were performed using a constant single scattering albedo (omega(o)). Our approach can be potentially applied to other regions previous adjustment of empirical model coefficients due to variations of omega(o). The use of lab-derived models is feasible as a long as beta m, c and K-sys are related for different omega(o) values.