1. 北京师范大学地理学与遥感科学学院，遥感科学重点实验室，环境遥感与数字城市北京市重点实验室， 北京 100875 2. Northern Gulf Institute, Mississippi State University, MS 39529, USA
The Influence of Nonuniform Vertical Profiles of Chlorophyll Concentration on Apparent Optical Properties
XI Ying1, DU Ke-ping1*, ZHANG Li-hua1, Zhongping Lee2, LI Xiao-wen1
1. Research Center for Remote Sensing and GIS， School of Geography, Beijing Normal University, State Key Laboratory of Remote Sensing Science, Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, Beijing 100875, China 2. Northern Gulf Institute, Mississippi State University, MS 39529, USA
Abstract：Previous researches on ocean optics and ocean color were based on the assumption that inherent optical properties and optically significant constituents of seawater are homogeneous in the vertical direction. However, oceanographic observations show that the assumption is not always exact and the vertical inhomogeneity of them exists in the upper ocean. The purpose of the present research is to study the effect of nonuniform vertical profiles of chlorophyll concentration on apparent optical properties with radiative transfer model Hydrolight. The vertical profiles of chlorophyll concentration were approximated according to a Gaussian function (Lewis et al, 1983). The apparent optical properties of seawater with nonuniform chlorophyll concentration profiles were simulated with Hydrolight radiative transfer model and case-1 bio-optical model, and then compared with those for homogenous ocean whose chlorophyll concentration was identical to the background chlorophyll concentration of inhomogenous cases. The results reveal that the subsurface maximal chlorophyll concentration increases the remote sensing reflectance at the blue wavelength and decreases it at the green wavelength, nonuniform vertical profiles of chlorophyll concentration change the diffuse attenuation coefficient profiles and the angular structure of the light field in the seawater, and the diffuse attenuation coefficients maximum and average cosines minimum appear at the depth of the maximal chlorophyll concentration.
Key words：The vertical distribution of chlorophyll concentration;Remote sensing reflectance;Diffuse attenuation coefficient;Average cosines
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