Secchi Disk

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Related to Secchi disk depth: Secchi disk transparency

Secchi disk

[′sek·ē ‚disk]
An opaque white disk used to measure the transparency or clarity of seawater by lowering the disk into the water horizontally and noting the greatest depth at which it can be visually detected.

Secchi Disk


an instrument for measuring water transparency in a body of water. A white disk 30 cm in diameter, it is held horizontally and lowered into the water on a rope until it is no longer visible. The depth, in meters, at which it ceases to be visible is taken as a measure of the water transparency. The disk is named after A. Secchi, who measured the transparency of sea water by this method in 1865.

References in periodicals archive ?
Comparison of MODIS and landsat TM5 images for mapping tempo-spatial dynamics of Secchi disk depths in Poyang Lake National Nature Reserve, China.
Field and laboratory methods used for different variables Variable Abbreviation Unit Physical and chemical variables Water level WL cm Secchi disk depth Secchi m Water surface Temp [degrees]C temperature Dissolved oxygen DO mg [L.
1997) said that the remotely sensed data have widely been used to estimate major water quality variables such as chlorophyll-a, turbidity, suspended sediment concentration, Secchi disk depth, surface water temperature, wave height, and sea surface roughness.
It is a spreadsheet program that uses regionally calibrated lake-response functions and basic, user-defined watershed and lake characteristics to estimate in-lake P, N, and chl a concentrations, and Secchi disk depth.
Secchi disk depth (water column transparency) improved 340 percent.