In western Mongolia, braided streams of sand dunes stretch east-west
across the arid landscape. One ribbon of sand, spanning roughly 200
kilometers, extends from an area south of Khyargas
Lake in the west to a smaller lake, Telmen Nuur, in the east. In
between, sand dunes march past Har Nuur, or “Black Lake.”
The Advanced Land Imager (ALI) on
NASA’s Earth Observing-1 (EO-1) satellite captured this
natural-color image of Har Nuur on June 12, 2010. Camel-colored sand
dunes ripple along the lake’s northern shore. Along the southern
shore, sand dunes approach the lake in just two locations. A
triangle-shaped expanse of sand borders Har Nuur in the east, and a
tongue of sand intrudes into the lake in the west, pushing through a gap
in the nearby mountains. All of the sand dunes, however, form part of a
larger dune field nearly encircling the lake.
Har Nuur sits in the Valley
of Lakes of western Mongolia. Bordered by multiple
mountain ranges, the Valley of Lakes hosts remnant basins of larger
ancient lakes, dune fields, and salt marshes. Har Nuur, like other lakes
in the region, is a closed-basin lake fed by precipitation.
Hot, dry summers prevail in this part of the word, with frequent, hot
winds blowing from the northwest. Winds push the sand dunes eastward
past Har Nuur and the nearby mountains. The long, skinny dune field
pushing into the lake is a persistent feature. It was equally obvious
when astronauts on the International Space Station photographed Har Nuur in 2006.
NASA Earth Observatory image created by Jesse Allen, using EO-1 ALI data provided courtesy of the NASA EO-1 team. Caption by Michon Scott.
Acquired June 12, 2010, this natural-color image shows camel-colored sand dunes marching past Mongolia’s Har Nuur.
Har Nuur (“Black Lake”) is located in western Mongolia’s Valley of Lakes, part of a system of closed basins stretching across central Asia. These basins are the remnants of larger paleolakes (paleo- means “ancient”) that began to shrink approximately five thousand years ago as regional climate became drier. This oblique (looking at an angle) astronaut photograph captures the dynamic nature of the landscape of Har Nuur. The lake is encircled by sand dune fields that encroach on the lower slopes of the Tobhata Mountains to the west and south. Gaps in the mountains have been exploited by sand dunes moving eastward, indicating westerly winds. The most striking example is a series of dunes entering Har Nuur along its southwestern shoreline.