Sediment Off Southern Gulf Of Alaska • Earth.com

Last update: September 18th, 2019 at 6:00 pm

Sediment continued to pour into the Gulf of Alaska in mid-February, 2016. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite captured this true-color image on February 16 as it passed over southcentral Alaska. Sediment continued to pour into the Gulf of Alaska in mid-February, 2016. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite captured this true-color image on February 16 as it passed over southcentral Alaska.

Gray sediment discolors the waters of the Cook Inlet (west) while turquoise and tan colors flow from the Copper River. Most of the mouth of the Copper River lies under cloud, can be seen as an indent on the coastline near the east edge of this image. A swirling arc of turquoise can also be seen in Prince William Sound.

The natural sediment in this region comes primarily from the action of glaciers slowly grinding away at rock. Over time, glacial action can turn solid rock into a fine power. Called “glacial flour”, large quantities are carried by wind off the coast and into the Gulf of Alaska. Glacial sediments are also carried by water flowing over land and into the rivers. When sediment floats near the top of water, it appears tan, brown or grey from space. As sediment sinks, the reflectivity changes and so does the color, often appearing tan or turquoise. Because sediment can bring nutrients to feed microorganisms living in waters off the coast, some of the colorful swirls may also be caused by phytoplankton.

Gray sediment discolors the waters of the Cook Inlet (west) while turquoise and tan colors flow from the Copper River. Most of the mouth of the Copper River lies under cloud, can be seen as an indent on the coastline near the east edge of this image. A swirling arc of turquoise can also be seen in Prince William Sound.

The natural sediment in this region comes primarily from the action of glaciers slowly grinding away at rock. Over time, glacial action can turn solid rock into a fine power. Called “glacial flour”, large quantities are carried by wind off the coast and into the Gulf of Alaska. Glacial sediments are also carried by water flowing over land and into the rivers. When sediment floats near the top of water, it appears tan, brown, or gray from space. As sediment sinks, the reflectivity changes and so does the color, often appearing tan or turquoise. Because sediment can bring nutrients to feed microorganisms living in waters off the coast, some of the colorful swirls may also be caused by phytoplankton.

NASA

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