The Sor Kaydak is a salt marsh that leads into the northeastern
bulb of the Caspian Sea. This land depression is occasionally inundated by
water from the Caspian Sea, as both the marsh and the Sea lie at the same
elevation—29 meters below global
sea level. They are separated by a low bar of land that is just 1–2 meters
high. The central 50 kilometers of the 180 kilometer-long marsh depression is
shown in this astronaut photograph from the International Space Station.
Water in the marsh takes on different colors—from brown to pink
to light green, moving northeast to southwest—as a result of the interplay of
water depth and the resident organisms such as algae. Algae color varies
depending on water temperature and salinity.
Irregular gray areas (top left) are wet zones between low sand
dunes. These inter-dune flats are whitened with salt that comes from the
evaporation of Caspian Sea water. (The Sea is just beyond the top left of the
image.) The jagged line following the colored water is the limit of the wetting
zone (or perimeter), an irregular zone influenced by wind and the depth of
water in the marsh.
Small cliffs mark the eastern margin of the depression that
contains Sor Kaydak. Above the cliffs, a plateau—about 200 meters above the
salt marsh, 160 meters above global sea level—extends eastward for hundreds of
kilometers. Here the plateau is occupied by a dense pattern of well heads,
which appear as a geometric pattern of tan dots. By contrast, the west margin
(image left) rises less than 10 meters above the marsh.
The straight line visible at image center is a pipeline built to
take oil to a terminal on the Caspian shore 100 kilometers northwest of the
area shown here.
Astronaut photograph ISS031-E-30896 was acquired on May 11, 2012, with a Nikon D2Xs digital camera
using a 180 mm lens, and is provided by the ISS Crew Earth Observations
experiment and Image Science & Analysis Laboratory, Johnson Space Center.
The image was taken by the Expedition 31 crew. It has been cropped and enhanced to improve contrast, and lens
artifacts have been removed. The International Space Station
Program supports
the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the
greatest value to scientists and the public, and to make those images freely
available on the Internet. Additional images taken by astronauts and cosmonauts
can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by M. Justin Wilkinson, Jacobs/ESCG at NASA-JSC.
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