大连港海域石油类物质比吸收系数特征分析

利用2018年8月25-27日和2019年5月15-17日在辽宁省大连港及周边海域测定的不同站点、不同时刻的遥感反射比Rrs,以及不同深度的水体吸收系数和石油类物质浓度数据,分析了水体石油类物质比吸收系数ao*(λ)的光谱变化规律和在参考波段440nm处的比吸收系数ao*(440)的垂向分布特征;将基于遥感反射比Rrs估算有色溶解有机物CDOM(Colored Dissolved Organic Matter)吸收系数和水体油浓度Co的模型应用于LANDSAT8卫星数据,反演出该海域ao*(440)和油浓度专题图,并分析了两者的空间分布特征。结果表明:(1)ao*(λ)的光谱分布特征遵循e指数衰减方程的变化规律;由于潮汐作用的影响,不同来向海水的石油类物质浓度不同,导致不同时刻不同站点的ao*(λ)的光谱斜率有一定的差异;(2)CDOM与油物质的混合比吸收系数ago*(440)随深度的垂向变化没有明显的规律,这也是由于涨落潮变化使得不同来向的海水组分有差异所致;(3)ao*(440)水平变化具有明显的规律;在石油污染浓度Co高的海域,ao*(440)呈现低值,在Co低的海域,ao*(440)呈现高值。

Analysis on the Characteristics of Specific Absorption Coefficient of Petroleum-Polluted Water in Dalian port

Absorption coefficients and petroleum substances concentration data of different depths were obtained in Dalian Port and its adjacent sea area in Liaoning Province on August 25-27,2018 and May 15-16,2019.The remote sensing reflectance at different stations and different time were used.The spectral change regulations of the specific absorption coefficients ao*(λ)of petroleum substances in water and the vertical distribution characteristics of the specific absorption coefficient ao*(440)at the reference band 440 nm were analyzed.The retrieval models of CDOM(Colored Dissolved Organic Matter)absorption coefficient and petroleum substances concentration in water Co based on the remote sensing reflectance were applied to the LANDSAT8 data to get the ao*(440)and petroleum substances concentration thematic map,and the spatial variation characteristics of ao*(440).The petroleum substances concentration were further analyzed.The results showed that:(1)The spectral distribution characteristics of ao*(λ)still follows the e-exponential decay equation;due to the influence of tide,the petroleum substances concentration in the seawater coming from different directions is different,leading to the variation of spectral slope of ao*(λ)at different stations and times.(2)The vertical variation of ago*(440)with depth has no obvious regulation,which is also because of the composition variation of seawater coming from different directions during flooding and ebbing tide.(3)The horizontal variation has obvious regularity:the higher Co concentration,the smaller ao*(440),and ao*(440)is high in the sea area with low Co concentration.