Biases in ocean color over a Secchi disk
Biases in ocean color over a Secchi disk
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DOI：
10.1364/oe.25.0a1124
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发表时间：
2017-11-27
期刊：
影响因子：
3.8
通讯作者：
Pitarch, Jaime
中科院分区：
文献类型：
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作者：
Pitarch, Jaime
最古老的海洋颜色测量记录包括与标准化颜色等级(FU)的目测比较。通过对FU存档数据的分析，可以构建一个长达百年的时间序列。FU的现场测量方案要求在塞奇圆盘(SD)上方的水柱上估计其所感知的颜色，该水柱位于它看不见的深度的一半处，而卫星仅在水柱上提取FU。我在本文中指出，这两种方法会导致不同的FU读数，因此，将这两种数据合并将产生人为的趋势。在情况1水域中，辐射传输模拟表明，相对于没有SD，在SD上的测量在0和+2之间移动Fu，并且不存在以单一方式将两者联系在一起的可能性。如果颜色用色调角度表示，则发现一种单义关系，色调角度可以从光谱或RGB图像中计算出来。(C)2017年美国光学学会
The oldest record of ocean color measurements consists of visual comparisons to a standardized color scale, the Forel-Ule scale (FU). Analysis of FU archived data allows the construction of a century-long time series. In situ protocols of FU measurements require the perceived color to be estimated over the water column above a Secchi disk (SD) at half of the depth where it goes out of sight, whereas satellites retrieve FU over the water column alone. I show in this article that these two methodologies lead to different FU readings and thus, merging both kinds of data will create artificial trends. In case 1 waters, radiative transfer simulations show that measuring over a SD shifts FU between 0 and + 2 in respect to no SD, and there exists no possibility to relate the two in a univocal fashion. A univocal relationship is found if color is expressed in terms of the hue angle, which can be calculated from light spectra or RGB images. (C) 2017 Optical Society of America