The quasi-analytical algorithm of ocean inherent optical properties using two reference wavelengths

The total absorption coefficient a(λ) and total backscattering coefficient bb(λ) are the basic inherent optical properties (IOPs) in ocean color remote sensing, which is the key to connect appearance optical properties (AOPs) from the remote sensor and the concentration of water component. In this paper, based on the stable and strong spectral relationship of the absorption coefficient (excluding the contribution of pure water) and particle backscattering coefficient at 510nm and 555nm, a new quasi-analytical remote sensing IOPs algorithm with two reference wavelengths is developed. The absorption coefficient and particle backscattering coefficient at 510nm and 555nm is calculated firstly through algebraic equations, and then based on the spectral model of particle backscattering coefficient, the a(λ) and bb(λ) at the other wavelength are extrapolated. Three optical data sets are used to validate the algorithm, including the in situ data set of China Yellow Sea and East China Sea in the spring of 2003, the synthesis data set and the global in situ data set from IOCCG. Meanwhile, the performance of this new algorithm is also compared with the results of GSM01 and Lee-QAA algorithms with the ECS data set. The results show that, in the coastal area with high influence of terrestrial material, the two reference wavelength algorithm has better flexibility for the special optical water.