Barchan and Linear Dunes
NASA/JPL/UArizona
Barchan and Linear Dunes
ESP_062731_2645  Science Theme: Aeolian Processes
This image shows two types of sand dunes on Mars. The small dots are called barchan dunes, and from their shape we can tell that they are upwind. The downwind dunes are long and linear.

These two types of dunes each show the wind direction in different ways: the barchans have a steep slope and crescent-shaped “horns” that point downwind, while the linear dunes are stretched out along the primary wind direction. Linear dunes, however, typically indicate a wind regime with at least two different prevailing winds, which stretch out the sand along their average direction.

In several places in this image, you can find barchan dunes turning into linear dunes as they are stretched out, but they both seem into indicate the same wind direction.

Written by: HiRISE Science Team  (13 January 2020)
 
Acquisition date
14 December 2019

Local Mars time
13:55

Latitude (centered)
84.209°

Longitude (East)
323.817°

Spacecraft altitude
318.9 km (198.2 miles)

Original image scale range
32.0 cm/pixel (with 1 x 1 binning) so objects ~96 cm across are resolved

Map projected scale
25 cm/pixel

Map projection
Polarstereographic

Emission angle
5.3°

Phase angle
59.3°

Solar incidence angle
63°, with the Sun about 27° above the horizon

Solar longitude
120.5°, Northern Summer

For non-map projected images
North azimuth:  113°
Sub-solar azimuth:  322.5°
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POSTSCRIPT
NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.