Salt and Spectacle: Satellite Reveals East Africa’s Pink Lakes

The European Space AgencyThe European Space Agency (ESA) is an intergovernmental organization dedicated to the exploration and study of space. ESA was established in 1975 and has 22 member states, with its headquarters located in Paris, France. ESA is responsible for the development and coordination of Europe's space activities, including the design, construction, and launch of spacecraft and satellites for scientific research and Earth observation. Some of ESA's flagship missions have included the Rosetta mission to study a comet, the Gaia mission to create a 3D map of the Milky Way, and the ExoMars mission to search for evidence of past or present life on Mars.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>European Space Agency’s Copernicus Sentinel-2 mission captures the colorful waters of two salty lakes in East Africa: Lake Natron in northern Tanzania and Lake Magadi in southern Kenya.

The Unique Ecology of Lake Natron

Lake Natron, the large lake at the bottom of the image, is 56 km (35 miles) long. It is rather shallow, only reaching a depth of 3 m (10 feet), although its depth varies during the year. Despite the lake being very salty in a region that suffers scorching temperatures, the lake basin is recognized as a Ramsar wetland of international importance. It is the only regular breeding area for lesser flamingos in East Africa. There can be as many as 2.5 million flamingos congregating on the lake, which also offers a habitat for thousands of other speciesA species is a group of living organisms that share a set of common characteristics and are able to breed and produce fertile offspring. The concept of a species is important in biology as it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted one is the biological species concept, which defines a species as a group of organisms that can interbreed and produce viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>species of waterbird.

Lake Magadi’s Geological and Industrial Significance

The smaller Lake Magadi, at the center top, is located in a vast depression in an area of volcanic rock. No permanent river enters the lake, which is fed only by surface runoff when it rains. Like Natron, Magadi has a notably high salt content – in some places, the salt is up to 40 m (130 feet) thick – and it’s one of the few places on Earth where the mineral trona forms naturally. Trona is used for glass manufacturing, fabric dyeing, and paper production.

Capturing Colors Through Advanced Imaging

This image was acquired on February 12, 2023, during the short dry season, immediately before the main rainy season that begins in March. Owing to algae that thrive on the salt, both lakes are naturally red or pink, especially during the dry season when water evaporates and the salts become more concentrated. Here, however, the colors are because the image processing included Sentinel-2’s near-infrared channel, which helps to reveal different information than what is yielded in a natural color image (see image below).

The Copernicus Sentinel-2 mission takes us over two saline lakes in East Africa: the larger Lake Natron in northern Tanzania and the smaller Lake Magadi, just over the border in Kenya. This image was captured on February 3, 2019. Credit: Contains modified Copernicus Sentinel data (2019), processed by ESA, CC BY-SA 3.0 IGO

While heavy shades of red highlight vegetated areas and dominate this false-color image, the seasonal flowering of algae in the lakes appears green. The bright white and blue areas along the shores depict a mixture of sand, salt, and mud flats. Salt crusts, resulting from evaporation caused by high temperatures, can be spotted as white dots speckling the waters.

Sentinel-2 in Environmental Monitoring

Sentinel-2 is a two-satellite mission to supply the coverage and data delivery needed for Europe’s Copernicus program. The mission’s frequent revisits over the same area and high spatial resolution allow to measure changes in the conditions of inland water bodies – one of the mission’s main applications along with land cover, agriculture, and forestry.