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Secchi Disk Depth: A New Theory And Mechanistic Model For Underwater Visibility, Zhongping Lee, Shaoling Shang, Chuanmin Hu, Keping Du, Alan Weidemann, Weilin Hou, Junfang Lin, Gong Lin

Marine Science Faculty Publications

Secchi disk depth (ZSD) is a measure of water transparency, whose interpretation has wide applications from diver visibility to studies of climate change. This transparency has been explained in the past 60 + years with the underwater visibility theory, the branch of the general visibility theory for visual ranging in water. However, through a thorough review of the physical processes involved in visual ranging in water, we show that this theory may not exactly represent the sighting of a Secchi disk by a human eye. Further, we update the Law of Contrast Reduction, a key concept in visibility …