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Gauging the Hue of the Sea

scientists testing ocean color tile

Testing the spectral properties of the tile.

Credit: Joaquim Goes/NOAA

The world's oceans face multiple threats, and fisheries, marine biologists, and environmental scientists need accurate and timely data about changing conditions. One important tool is color monitoring.

The color of scattered light from sunlit seawater contains important information about ocean health and concentration of substances such as chlorophyll. But taking color measurements from ships has been difficult because of interference from other sources of light -- for example, skylight reflected off the ocean's surface.

Now PML scientists have designed and produced a sand-blasted blue tile to serve as an ocean-like reflectance sample. It is currently deployed on NOAA's 2014 Marine Optical Characterization Cruise. This 10-day cruise with 44 planned observation points will sample the Gulf Stream and coastal waters up and down the East Coast (Charleston, SC to the Chesapeake Bay) in a sawtooth pattern.

Before deployment, PML scientists measured the reflectance of the tile using NIST's Spectral Tri-function Automated Reference Reflectometer (STARR). The tile will be re-measured at NIST following completion of the cruise to assess the stability of the tile for use as a validation or "check" standard for ocean color measurements.

Released November 24, 2014, Updated January 8, 2018