Today’s Image of the Day from NASA Earth Observatory shows dust clouds streaming over the Gulf of Alaska in the fall of 2020.
According to NASA, the dust originated upstream in the Copper River Valley, where glaciers crush rocks into a very fine silt that is referred to as “glacial flour.”
The silt is carried south in river water, where it is deposited along the delta and the shore. The silt particles are so fine that they are easily picked up and carried away by wind.
The dust clouds in Alaska contain iron, which is distributed into the Gulf of Alaska when the dust settles. This iron may be an important source of nutrients for phytoplankton.
“Although the magnitude of Alaskan dust events is not as massive as those seen in the North Atlantic, they may be more effective in terms of fertilization potential per unit of mass of dust because glacial silt is more soluble,” explained Santiago Gassó, an atmospheric scientist at NASA’s Goddard Space Flight Center.
“Until a few years ago, we knew about dust activity in this part of the world in a very anecdotical way, but with the advent of better online platforms to search for images, as well as the increase of number of satellites in operation, the surveillance of this are – and other high latitude dust sources such as Greenland – is easier to carry out. This has contributed to the discovery that high latitude dust activity is fairly common, and it dispels the belief that dust storms are a purely hot-environment phenomenon.”
The image was captured on October 22, 2020 by the Operational Land Imager (OLI) on Landsat 8.
Image Credit: NASA Earth Observatory