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首页> 外文期刊>Estuarine Coastal and Shelf Science >Pre-monsoon bio-optical properties in estuarine, coastal and Lakshadweep waters
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Pre-monsoon bio-optical properties in estuarine, coastal and Lakshadweep waters

机译：河口，沿海和拉克肖普普水域的季风前生物光学特性

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Spatial patterns of bio-optical properties were studied in coastal, estuarine and Lakshadweep waters during the pre-monsoon period. This was carried out by analysing the profiles of downward irradiance, upward radiance and water samples collected from 26 stations. The apparent optical properties such as subsurface reflectance (R) and diffuse attenuation coefficient (k) derived from these profiles were processed to generate inherent optical properties, a (total absorption coefficient) and b_b (total backscattering coefficient). Highly variable surface-coloured dissolved organic matter (CDOM) absorption (1.8-21.6 m~(-1) at 440 nm) was observed in the coastal waters. The distribution of optical properties a and b_b reflected the distribution of optically active constituents with CDOM contributing to most of the variation in coastal waters, sediment in estuarine waters, and chlorophyll a and water molecules in Lakshadweep waters. The spectral remote sensing reflectance (R_(rs)(λ)) is a linear function of a and b_b. k was lowest and R was at maximum in the green part of the electromagnetic spectrum (EMR) in estuarine and coastal waters while this is true in the blue region of EMR in Lakshadweep waters. A linear relationship was seen between downwelling diffuse attenuation coefficient (k_d) at 490 nm and attenuation of photosynthetically available radiation (k_(PAR)). Examination of the light field revealed maximum chlorophyll at greater depth in Lakshadweep waters and at shallow depth in coastal waters, with no well-defined maxima in the estuarine waters. An exponential inverse relation is evident between k_d (490) and depth of chlorophyll maxima. Through a radiative transfer computation, a ratio between water-leaving radiance at 400 and 670 nm is found to be an index of CDOM and hence could be used to retrieve it through an optical sensor.
机译：在季风前期，研究了沿海，河口和拉克肖普普水域生物光学特性的空间格局。这是通过分析从26个站点收集的向下辐照度，向上辐照度和水样的剖面来进行的。从这些轮廓得出的表观光学特性（例如，表面下反射率（R）和扩散衰减系数（k））经过处理以生成固有的光学特性，即a（总吸收系数）和b_b（总反向散射系数）。在沿海水域观察到高度有变化的表面有色溶解性有机物（CDOM）吸收（在440 nm处为1.8-21.6 m〜（-1））。光学特性a和b_b的分布反映了光学活性成分的分布，其中CDOM导致了沿海水域，河口水的沉积物以及Lakshadweep水域的叶绿素a和水分子的大部分变化。光谱遥感反射率（R_（rs）（λ））是a和b_b的线性函数。在河口和沿海水域的电磁频谱（EMR）的绿色部分中，k最低，R最高，而在Lakshadweep水域的EMR的蓝色区域中，k最低。在490 nm处的向下扩散漫射衰减系数（k_d）与光合有效辐射的衰减（k_（PAR））之间发现线性关系。对光场的检查显示，Lakshadweep水域的最大叶绿素含量最高，而沿海水域的叶绿素含量最高，河口水域没有明确定义的最大值。 k_d（490）和最大叶绿素深度之间存在指数反比关系。通过辐射传递计算，发现在400和670 nm处的出水辐射率之间的比率是CDOM的指标，因此可用于通过光学传感器检索。

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