The largest dust storm ever seen across Greenland has been revealed in a series of stunning satellite imagery.
The unusual event is caused by "glacier flour", a fine-grained sludge formed by grinding and crushing glaciers.
Scientists were never able to investigate the phenomenon in major storms until a month ago, when satellite imagery stormed.
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On September 29, 2018, the Moderate Resolution Imaging Spectroradiometer (MODIS) of NASA's Terra satellite and a European Space Agency (ESA) Sentinel-2 sensor collected images of a sizable cloud of cum pouring from the east coast of Greenland
WHAT IS GLACIAL FLOUR?
Glacier flour is a fine-grained silt that is formed by grinding and crushing rocks.
Glacier flour is the smallest sediment size, much smaller than sand, and is responsible for the milky colored water in the rivers, streams and lakes fed by glaciers.
Since this sediment is so fine, it can easily be transported and suspended by water.
In this case, NASA says the glacier flour was probably produced by several glaciers in the valley, which were then carried south by meltwater streams and deposited in the river landscape.
"This is by far the biggest event discovered and reported by satellites of which I know," said Santiago Gassó, an atmospheric scientist at NASA's Goddard Space Flight Center.
On October 3, he noticed the storm for the first time.
"We've already seen some examples of small dust events in front of it, but they're hard to spot with satellites because of clouds," said Joanna Bullard of Loughborough University.
"When dust events occur, field data from Iceland and West Greenland suggests that they rarely last longer than two days."
On September 29, 2018, the Moderate Resolution Imaging Spectroradiometer (MODIS) of NASA's Terra satellite and a sensor from the European Space Agency's Sentinel-2 (ESA) gathered the first images of the storm that emanated a sizeable silt cloud from Greenland's east coast.
The source was a braided river valley about 130 kilometers northwest of Ittoqqortoomiit, a village at a latitude of 73 degrees north.
This is the village north of the north coast of Alaska.
The series of Landsat and Sentinel 2 images shows the river floodplains from which the stream flows in Scoresby Sound.
With the drying of the soil on the Au, the Au was getting grayer.
The northwest wind on September 29 was strong enough to lift glacier flour into the air.
On the 21st, 23rd, 29th and 30th of September, the series of Landsat and Sentinel 2 images above and below shows the floodplains in which the stream flows in Scoresby Sound. With the drying of the soil on the floodplain (first two pictures), the floodplain became increasingly gray. The northwest wind on September 29 was strong enough to lift glacier flour into the air.
The glacier flour was probably produced by several glaciers higher up in the valley, then carried south by meltwater streams and deposited in the floodplain.
As the water level in the stream decreased in the fall, the flood plain dried out and became susceptible to the wind.
In this case, according to Bullard, the wind was triggered by the combination of a gravure system that crossed the Greenland ice sheet, followed by a high-pressure backing.
Since dust events are hardly understood in large latitudes, they are usually not included in atmospheric and climate models.
Gasso hopes that they will eventually be taken up as they could affect air quality, snow reflectivity and even marine biology.