An evaluation of inversion models for retrieval of inherent optical properties from ocean color in coastal and open sea waters around Korea

Abstract

This study was aimed to investigate three inversion models (currently in use with Moderate Resolution Imaging Spectroradiometer and Sea-viewing Wide Field-of-view Sensor data processing), namely constrained Linear Matrix (LM), Quasi-analytical algorithm (QAA) and GSM semi-analytical models (GSM). These models were applied to large bio-optical data sets (collected from coastal and open sea waters around Korea) to retrieve inherent optical properties (IOPs) such as absorption coefficients of phytoplankton (aph), colored dissolved and detrital organic matters (acdm), and particulate backscattering coefficient (bbp) at five wavelengths (412, 443, 490, 510, and 555 nm). The derived IOP products were compared with in situ aph, acdm and bbp coefficients measured for the same remote sensing reflectance (Rrs(λ)) data sets used in the models and the uncertainties of the three models were assessed based on the standard statistical procedures (mean relative error MRE, root mean square error RMSE, slope, and coefficient of determination R2). It was found that all the three models tended to yield significant errors with varying magnitude at different wavelengths. Overall performance of the models assessed based on the above statistical means was found in the following order: LM > GSM > QAA for retrieving the aph, LM > GSM > QAA for retrieving the acdm, and QAA > GSM > LM for retrieving the bbp. Our analyses suggest that these models will require additional refinements with a full parameterization by a fully suited data set in order to produce accurate retrievals of IOPs in coastal and open sea waters around Korea.