NASA Terra MODIS Image: Bright Waters off the Namibian Coast
Ocean waters glowed bright peacock green off the northern Namibian coast in late November 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image on November 21, 2010.
These bright swirls of green occur along a continental shelf bustling with biological activity. Phytoplankton blooms often occur along coastlines where nutrient-rich waters well up from ocean depths. The light color of this ocean water suggests the calcite plating of coccolithophores.
Farther south along the coastline of Namibia, hydrogen sulfide eruptions occur fairly frequently. According to a study published in 2009, ocean currents deliver oxygen-poor water from the north.
Bacteria that break down phytoplankton consume oxygen, depleting the oxygen supply even more. In this oxygen-poor environment, anaerobic bacteria begin to produce hydrogen sulfide gas. When the hydrogen sulfide reaches oxygen-rich surface waters, pure sulfur precipitates into the water. The sulfur’s yellow colors sulfur deep blue ocean water bright green.
Phytoplankton blooms and the bacteria that break them down can create a complex network along a continental shelf. This swirl of peacock green could contain phytoplankton, sulfur, or a combination.
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