An optical model for deriving the spectral particulate backscattering coefficients in oceanic waters

Abstract

Abstract. An optical model is developed based on the diffuse attenuation coefficient (K d ) to estimate particulate backscattering coefficients b bp (λ) in oceanic waters. A large in situ data set is used to establish robust relationships between b bp (530) and b bp (555) and K d (490) using an efficient nonlinear least-square method which uses the trust region algorithm with Bisquare weights scheme to adjust the coefficients. These relationships are obtained with good correlation coefficients (R 2 = 0.786 and 0.790), low root mean square error (RMSE = 0.00076 and 0.00072) and 95 % confidence bounds. The new model is tested with three independent data sets: the NOMAD SeaWiFS Match ups, OOXIX IOP algorithm workshop evaluation data set (Version 2.0w APLHA), and IOCCG simulated data set. Results show that the new model makes good retrievals of b bp at all key wavelengths (from 412-683 nm), with statistically significant improvements over other inversion models. Thus, the new model has the potential to improve our present knowledge of particulate matter and their optical variability in oceanic waters.

A compilation of global bio-optical in situ data for ocean-colour satellite applications

“…The relation between the ratio rrs(490) / rrs(555) and bbp at 555 nm (Fig. 16c) shows a good agreement with the relation suggested by Tiwari and Shanmugam (2013). A total of 357 points exist for which these three variables are available (91 % from NOMAD).…”

“…For reference the solid line show the relation proposed by Tiwari and Shanmugam (2013). A search window of 2 nm was used for panels (a) and (b), and a search window of 5 nm was used for panels (c) and (d) to include data at 560 nm when not available at 555 nm.…”

A Semi-Analytic Model for Estimating Total Suspended Sediment Concentration in Turbid Coastal Waters of Northern Western Australia Using MODIS-Aqua 250 m Data

“…‚ For high-scattering coastal waters, b b (λ) is mainly due to the backscattering coefficient from particulate matter and water molecules, the backscattering coefficient contributions from other constituents are insignificant [75]. Further, in the red and NIR regions of the spectrum the scattering by water molecules becomes insignificant, thus we can make an assumption that total backscattering in the red and NIR regions is due to particulate matter only.…”

Optical Backscattering Measured by Airborne Lidar and Underwater Glider

“…More recent laboratory instruments are even lower than most previous measurements, with χ(175 • ) < 0.01 for several algal species [21]. There are also uncertainties in the wavelength dependence of this quantity [41][42][43]. For a power-law spectrum with an exponent of unity, the lidar backscattering would be 22% greater than that from glider.…”