Wednesday, June 7, 2017

The Northern Patagonian Icefield from space

The northern icefield covers about 4,000 square kilometers (about a quarter the size of the southern icefield). On April 16, 2017, the Operational Land Imager (OLI) on Landsat 8 captured this rare cloud-free image of the entire North Patagonian Icefield.
While the northern icefield is smaller than its southern counterpart, it still has 30 significant glaciers along its perimeter. Ice creeps downslope through mountain valleys and exits the through so-called “outlet glaciers.” Many come to an abrupt end on land, while others terminate in water. The water-terminating glaciers San Rafael and San Quintín are the icefield’s largest.

The San Quintin glacier currently ends in a piedmont lobe, and illustrates what San Rafael looked like before it receded. Until 1991, the glacier terminated on land, but with the glacier’s retreat, the basin has filled in with water to form a proglacial lake. (Note that the lake water is barely distinguishable from the ice due to its milky color.)
San Quintín does not flow as fast (1.1 kilometers per year) or calve as many bergs as San Rafael, but it is an impressive glacier on its own, standing as the second-largest in the North Patagonian Icefield. Together with San Rafael, the glaciers drain 37 percent of the icefield.

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