Desert dust over the Bay of Biscay •

Today’s Image of the Day from NASA Earth Observatory features Saharan dust over the Bay of Biscay, where a phytoplankton bloom makes the water appear bright green and blue. According to NASA, sediment runoff likely contributes to some of the color, especially in areas closer to the shore.

“For the past few decades, scientists have been observing natural ocean fertilization events – episodes when plumes of volcanic ash, glacial flour, wildfire soot, and desert dust blow out onto the sea surface and spur massive blooms of phytoplankton. But beyond these extreme events, there is a steady, long-distance rain of dust particles onto the ocean that promotes phytoplankton growth just about all year and in nearly every basin,” says NASA.

In a recent study, researchers from Oregon State University, the University of Maryland Baltimore County, and NASA set out to investigate how mineral dust from land fertilizes the growth of phytoplankton in the ocean. For the research, the team analyzed satellite observations and developed an advanced computer model.

“According to the new study, dust deposition onto the ocean supports about 4.5 percent of yearly global export production – a measure of how much of the carbon phytoplankton take up during photosynthesis sinks into the deep ocean. However, this contribution approaches 20 percent to 40 percent in some ocean regions at middle and higher latitudes,” explained NASA.

“Phytoplankton play a large role in Earth’s climate and carbon cycle. Like land plants, they contain chlorophyll and derive energy from sunlight through photosynthesis. They produce oxygen and sequester a tremendous amount of carbon dioxide in the process, potentially on a scale comparable to rainforests. And they are at the bottom of an ocean-wide food pecking order that ranges from tiny zooplankton to fish to whales.”

Lorraine Remer, a research professor at the University of Maryland Baltimore County, noted that dust particles can travel thousands of miles before falling into the ocean, where they nourish phytoplankton long distances from the dust source.

“We knew that atmospheric transport of desert dust is part of what makes the ocean ‘click,’ but we didn’t know how to find it,” said Professor Remer.

The image was captured on April 8, 2011 by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.

Image Credit: NASA Earth Observatory 

By Chrissy Sexton, Editor

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