Particulate Backscattering in the Global Ocean: A Comparison of Independent Assessments

How well do we know the particulate backscattering coefficient (b_bp) in the global ocean? Satellite lidar b_bp has never been validated globally and few studies have compared lidar b_bp to b_bp derived from reflectances (via ocean color) or in situ observations. Here, we validate lidar b_bp with autonomous biogeochemical Argo floats using a decorrelation analysis to identify relevant spatiotemporal matchup scales inspired by geographical variability in the Rossby radius of deformation. We compare lidar, float, and ocean color b_bp at the same locations and times to assess performance. Lidar b_bp outperforms ocean color, with a median percent error of 18% compared to 24% in the best case and a relative bias of -11% compared to -21%, respectively. Phytoplankton carbon calculated from ocean color and lidar exhibits basin-scale differences that can reach ±50%.