A research on statistical retrieval algorithms and spectral characteristics of the total absorption coefficients in the Yellow Sea and the East China Sea

1 INTRODUCTION The Yellow Sea and the East China Sea are typical coastal Case-II waters with high sediment load and complicate optical properties. The total absorption coefficient of sea water is one of the main parameters influencing the calculation of o…

A research on statistical retrieval algorithms and spectral characteristics of the total absorption coefficients in the Yellow Sea and the East China Sea

This paper suggests a group of statistical algorithms for calculating the total absorption co-efficients based onin situ data of apparent optical property and inherent optical property collected with strict quality assurance according to NASA ocean bio-optic protocols in the Yellow Sea and the East China Sea in spring 2003. The band-ratios ofR _rs555,R _rs555 are used in the algorithms to derive the total absorption coefficients (a ₁) at 412, 440, 488, 510, 532 and 555nm bands, respectively. The average relative errors between inversed and measured values are less than 25.8%, with the correlative coefficients (R ²) being 0.75–0.85. Error sensitivity analysis shows that the maximum retrieval error is less than 24.0% at ±5% error inR _rs's. So the statistical algorithms of this paper are practicable. In this paper, the relations between the total absorption coefficients at 412, 488, 510, 532, 555 nm and that of 440nm are also studied. The results show that the relations between the total absorption coefficients of 400–600 nm and that of 440 nm are correlated well and all of their correlative coefficientsR ² are greater than 0.99. Furthermore, a regression analysis is also done for the slope of the linear relations and wavelengths, and theR ² is also 0.99. Thus it is possible to retrieve other bands' total absorption coefficients with only one band absorption value, which significantly reduce the number of unknown parameters in studying other ocean color related problems. Supported by the Subsystem of Calibration and Validation, HY-1 Ground Application System, National Satellite Ocean Application Service (NSOAS). China High-Tech “863” Project (Nos. 2001AA636010, 2002AA639160 and 2002AA639200). The Ocean Science Fund Sponsor Project for the Youth, State Oceanic Administration (No. 2005415). The Director's Science and Technology Fund Sponsor Project for the Youth, NSOAS.