Secchi disk

noun

1. an opaque, white or black-and-white disk used to measure the cloudiness or turbidity of ocean water by the point at which it is no longer visible from the surface.

Secchi disk

1. An instrument used for measuring the clarity of water, especially seawater. It consists of a circular plate divided into alternating black and white quadrants and attached to a long measuring tape. The plate is lowered into the water, and the depth at which it is no longer visible from the surface is recorded. The Secchi disk is named after its inventor, Italian astronomer Angelo Secchi (1818–1878).
2. See also Secchi depth

Word History and Origins

Origin of Secchi disk¹

First recorded in 1910–15; named after Pietro Angelo Secchi (1818–78), Italian astronomer who invented it in 1865

Example Sentences

The researchers measure the clarity of the lake by lowering a 10-inch-wide white disk, known as a Secchi disk, into the water and marking at what depth the disk remains visible.

From Los Angeles Times

"Bluefin tuna have been extensively overfished during the 20th century and the stock was close to its lowest in 1990, a fact that further indicates the recent changes in distribution are most likely environmentally driven rather than due to fisheries management and stock recovery," said co-author Dr Richard Kirby from the Secchi Disk Foundation.

From BBC

In response to these findings, marine biologist Richard Kirby set up the Secchi Disk Project, a citizen science study that allowed seafarers to submit their recordings of plankton abundance and increase the volume of data available to scientists monitoring the health of the oceans' plankton.

From BBC

They have become the first commercial fishers to gather data for the Secchi Disk Study, which is gathering data on the state of the oceans' phytoplankton.

From BBC

Mr Steer and other members of the South Devon and Channel Shellfishermen association have been collecting data for the Secchi Disk Study, a citizen science project.

From BBC