Bai Ruofeng, He Xianqiang, Bai Yan, Li Teng, Zhu Qiankun, Gong Fang
Opt Express. 2020 Sep 28;28(20):29714-29729. doi: 10.1364/OE.401855.
Ultraviolet (UV) bands have attracted considerable attention in regard to satellite ocean color remote sensing due to their potential application in atmospheric correction, oil spill detection, and water organic matter retrieval. However, the characteristics of the water spectrum in the UV bands are still poorly understood. In this study, by extending the bio-optical model from traditional visible light wavelengths to UV light wavelengths, the water spectrum in UV bands under different water types was simulated by using the HydroLight water radiative transfer model, and influences of ocean color components on the water spectrum in UV bands were investigated. Results showed that remote sensing reflectance (Rrs) in the UV bands decreased rapidly with the increase in chlorophyll concentration (Chl) and colored dissolved organic matter (CDOM). In clean waters, Rrs in the UV bands was relatively large and sensitive to changes in Chl and CDOM, which could be of benefit for satellite retrieval of water organic matter. In eutrophic water, Rrs in the UV bands was quite low, and thence the UV bands could be used as a reference band for atmospheric correction. Compared to the monotonic decreasing effects of Chl and CDOM, concentration of non-algal particles (NAP) had a complex effect on Rrs in the UV bands, i.e., increase and decrease in Rrs in low-moderately and highly turbid waters, respectively. Thus, the traditional model for the relationship between Rrs and inherent optical properties (IOPs) could be applied to the UV bands in clean waters; in highly turbid waters, however, its deviation increases and empirical coefficients in the model should be improved.
紫外（UV）波段因其在大气校正、溢油检测和水体有机物反演方面的潜在应用，在卫星海洋水色遥感中备受关注。然而，人们对紫外波段的水体光谱特征仍了解不足。在本研究中，通过将生物光学模型从传统可见光波长扩展到紫外光波长，利用HydroLight水体辐射传输模型模拟了不同水体类型下紫外波段的水体光谱，并研究了海洋水色组分对紫外波段水体光谱的影响。结果表明，紫外波段的遥感反射率（Rrs）随叶绿素浓度（Chl）和有色溶解有机物（CDOM）的增加而迅速降低。在清洁水体中，紫外波段的Rrs相对较大，且对Chl和CDOM的变化敏感，这有利于卫星反演水体有机物。在富营养化水体中，紫外波段的Rrs相当低，因此紫外波段可作为大气校正的参考波段。与Chl和CDOM的单调递减效应相比，非藻类颗粒（NAP）浓度对紫外波段的Rrs有复杂影响，即在低-中度和高浑浊水体中分别导致Rrs增加和降低。因此，传统的Rrs与固有光学特性（IOPs）关系模型可应用于清洁水体的紫外波段；然而，在高浑浊水体中，其偏差增大，模型中的经验系数应予以改进。
