Secchi depth

American  

noun

1. the depth at which a Secchi disk is no longer visible from the surface of ocean water.

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Secchi depth Scientific  

/ sĕk′ē /

1. A measure of the clarity of water, especially seawater. Secchi depth is measured using a circular plate, known as a Secchi disk, which is lowered into the water until it is no longer visible. High Secchi depths indicate clear water; whereas low Secchi depths indicate cloudy or turbid water.

2. See also Secchi disk

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Example Sentences

Federal and state regulators have set a 97-foot 4-inch Secchi depth as the lake’s “clarity restoration target.”

From Los Angeles Times

It is lowered into the water on the end of a tape measure, and when it is no longer visible from the surface, the reading - known as the Secchi depth - is recorded.

From BBC

"We can now collect Secchi depth measurements from all over the world's oceans and add that to the data from the 1860s to make a continuous - with a slight dip - record to see what is happening to the phytoplankton in the oceans," he said.

From BBC