Open AccessVariability of particulate backscattering ratio and its relations to particle intrinsic features in the Bohai Sea, Yellow Sea, and East China Sea
Author(s) -
Deyong Sun,
Xiaoping Su,
Shengqiang Wang,
Zunbin Ling,
Zhihua Mao,
Yijun He
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.003074
Subject(s) - particulates , dimensionless quantity , mie scattering , lidar , density ratio , environmental science , chlorophyll a , particle size , atmospheric sciences , spectral slope , particle (ecology) , mineralogy , scattering , physics , light scattering , oceanography , geology , optics , spectral line , chemistry , organic chemistry , mechanics , paleontology , biochemistry , astronomy
Using two field cruise observations collected during September and December 2016 in the Bohai Sea (BS), Yellow Sea (YS), and East China Sea (ECS), our study explores the variability of the particulate backscattering ratio (i.e., a ratio of particulate backscattering, b bp in m -1 , to particulate scattering, b p in m -1 , denoted as b˜ bp , dimensionless). A large variation of b˜ bp (using 550 nm as a delegate) in magnitude is observed in the study regions, ranging from 0.0004 to 0.043 (with an average of 0.015 ± 0.0082), which implies optically complex water conditions. Spectral variation in b˜ bp is analyzed quantitatively by our proposed so-called "spectral dependence index," K, recommended as a standard way to determine quantitatively the spectral dependence of b˜ bp in water bodies worldwide. The driving mechanism on the b˜ bp variability in the study regions is researched for the first time, based on those synchronous data on particle intrinsic attributes, herein mainly referring to particle concentration (TSM, for the content of total suspended matter), composition (using a ratio of Chla/TSM as a surrogate, where Chla refers to the content of chlorophyll a), mean particle size (D A ), and mean apparent density (ρ a ). The TSM, Chla/TSM, and D A cumulatively contribute most (97.8%) of the b˜ bp variability, while other factors, such as the ρ a , show a weak influence (0.04%). Meanwhile, we model b˜ bp with direct linkages to TSM, Chla/TSM, and D A by using a linear regression method, with low estimation errors (such as mean absolute percentage error, MAPE, of about 14%). In short, our findings promote an understanding on the essence of the b˜ bp in the BS, YS, and ECS, and are significantly beneficial to the comprehensive grasp of those complex features on suspended particles and those related to biogeochemical processes in marine waters.