Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
Department of Forest Resources, University of Minnesota, Saint Paul, MN 55455, USA.
Sensors (Basel). 2023 Jan 17;23(3):1071. doi: 10.3390/s23031071.
The dominant wavelength and hue angle can be used to quantify the color of lake water. Understanding the water color is important because the color relates to the water quality and its related public perceptions. In this paper, we compared the accuracy levels of two methods in calculating dominant wavelength and hue angle values using simulated satellite data calculated from in situ reflectance hyperspectra for 325 lakes and rivers in Minnesota and Wisconsin. The methods developed by van der Woerd and Wernand in 2015 and Wang et al. in 2015 were applied to simulated sensor data from the Sentinel-2, Sentinel-3, and Landsat 8 satellites. Both methods performed comparably when a correction algorithm could be applied, but the correction method did not work well for the Wang method at hue angles < 75°, equivalent to levels of colored dissolved organic matter (CDOM, ) > ~2 m or chlorophyll > ~10 mg m. The Sentinel-3 spectral bands produced the most accurate results for the van der Woerd and Wernand method, while the Landsat 8 sensor produced the most accurate values for the Wang method. The distinct differences in the shapes of the reflectance hyperspectra were related to the dominant optical water quality constituents in the water bodies, and relationships were found between the dominant wavelength and four water quality parameters, namely the Secchi depth, CDOM, chlorophyll, and Forel-Ule color index.
主波长和色调角可用于量化湖水的颜色。了解水色很重要，因为颜色与水质及其相关的公众认知有关。在本文中，我们比较了两种方法在计算主波长和色调角值方面的精度水平，这两种方法是使用明尼苏达州和威斯康星州 325 个湖泊和河流的现场反射率高光谱数据计算得到的模拟卫星数据。2015 年 van der Woerd 和 Wernand 以及 2015 年 Wang 等人开发的方法应用于 Sentinel-2、Sentinel-3 和 Landsat 8 卫星的模拟传感器数据。在可以应用校正算法的情况下，两种方法的性能相当，但校正方法在色调角<75°时效果不佳，相当于有色溶解有机物（CDOM，）>2 m 或叶绿素>10 mg m。van der Woerd 和 Wernand 方法产生的最准确结果是 Sentinel-3 光谱带，而 Wang 方法产生的最准确结果是 Landsat 8 传感器。反射率高光谱的明显差异与水体中的主要光学水质成分有关，并且在主波长和四个水质参数之间建立了关系，即塞奇深度、CDOM、叶绿素和福雷尔-乌勒颜色指数。
