现场光谱观测是水色遥感真实性检验的基础。 传统基于航次站位观测获取的水体光谱数据少, 难以满足快速变化的近岸水体遥感产品真实性检验的需求。 为此, 国际上开始发展水体光谱连续观测系统, 但目前近岸水体光谱连续观测系统仍较少, 特别是在高浊度、 高动态的水体。 针对该问题, 在杭州湾建立了一套基于海上塔台的高浑浊水体光谱高频观测系统。 该系统每3 min获取一次水体光谱数据, 实现与过境卫星观测时间的匹配。 本文重点开发了基于海上塔台特点的水体光谱高频观测数据的处理方法, 实现了晴空、 耀斑、 阴影、 弱光照等自动判别, 并对处理结果进行了检验。 结果表明, 塔台观测获得的归一化离水辐亮度光谱与船测结果具有较高的一致性, 相关系数大于0.99, 平均相对误差为9.96%。 此外, 对塔台水体高频观测系统的长期观测能力进行了评价, 结果表明, 尽管系统运行一年之久, 系统与便携式地物光谱仪ASD同步观测获得的水体归一化离水辐亮度在谱形和数值上一致性均较好, 相关系数大于0.90, 平均相对误差为6.48%。 同时, 利用系统高频观测的水体光谱可有效监测悬浮物浓度随潮汐的快速动态变化。 杭州湾塔台水体高频观测系统为进一步开展浑浊水体水色卫星遥感产品真实性检验提供了丰富的现场光谱数据, 特别是高时间分辨率的静止轨道水色卫星遥感产品的真实性检验。

In situ measurement of water spectrum is the basis of the validation of the ocean color remote sensing. The traditional method to obtain the water spectrum is based on the shipboard measurement at limited stations, which is difficult to meet the requirement of validation of ocean color remote sensing in the highly dynamic coastal waters. To overcome this shortage, continuously observing systems of water spectrum have been developed in the world. However, so far, there are still few high-frequency observation systems of the water spectrum in coastal waters, especially in the highly turbid and high-dynamic waters. Here, we established a high-frequency water-spectrum observing system based on tower in the Hangzhou Bay. The system measures the water spectrum at a step of 3 minutes, which can fully match the satellite observation. In this paper, we primarily developed a data processing method for the tower-based high-frequency water spectrum data, to realize automatic judgment of clear sky, sun glint, platform shadow, and weak illumination, etc., and verified the processing results. The results show that the normalized water-leaving radiance spectra obtained through tower observation have relatively high consistency with the shipboard measurement results, with correlation coefficient of more than 0.99, and average relative error of 9.96%. In addition, the long-term observation capability of the tower-based high-frequency water-spectrum observing system was evaluated, and the results show that although the system has run for one year, the normalized water-leaving radiance obtained by this system have good consistency with the synchronously measurement by Portable spectrometer ASD in respect of spectral shape and value, with correlation coefficient of more than 0.90 and average relative error of 6.48%. Moreover, the water spectra from high-frequency observation by the system can be used to effectively monitor the rapid dynamic variation in concentration of suspended materials with tide. The tower-based high-frequency water-spectrum observing system provided rich in situ spectral data for the validation of ocean color remote sensing in turbid waters, especially for validation of the high temporal-resolution geostationary satellite ocean color remote sensing.