Forum for Science, Industry and Business

Abrupt cloud clearing events over southeast Atlantic Ocean are new piece in climate puzzle

Although clouds grow and dissipate all of the time, scientists think that these low-lying clouds off the coast of subtropical Africa are being disrupted not simply by wind from the continent, but rather by a wave mechanism.

Example of a westward-moving cloudiness transition in the southeast Atlantic off the coast of Africa. (left) regional view and (right)showing detail of the sharp edge of the transition boundary.

Credit: Satellite data courtesy of NASA Worldview.

Usage Restrictions: Include credit to NASA Worldview; please do not edit caption language

For climate models, the way the clouds are being disrupted could make a big difference. The observations appear today in the journal Science.

"Low clouds are important because they help cool the climate," said David Mechem, University of Kansas associate professor of geography and atmospheric science and one of the paper's authors. "These are huge sheets of white clouds that reflect sunlight back to space. When we try to do climate predictions for 50 years in the future, it's important to get these clouds right."

Mechem worked with lead researcher Sandra Yuter and colleagues from North Carolina State University. The scientists worked together during the past few years, most recently to understand why the southeast Atlantic was averaging a bit less cloud cover than the other major regions of marine low clouds. Because of the relative lack of observations over the southeast Atlantic and African coast, their analysis was mostly based on satellite data.

"This is what we stumbled into -- dramatic clearing events," Mechem said. "We fixated on this because of its potential importance for climate models to represent this feature."

The scientists set out to understand how these dramatic clearing events were happening. Winds from subtropical Africa do not simply blow the clouds westward across the ocean.

"What we think is going on is that the air flow from land to ocean overnight is triggering atmospheric waves that then move west," he said.

The wind flow offshore off the southwest African coast is a common weather phenomenon Floridians or anyone who has visited the Sunshine State's coasts knows, Mechem said. During the day, the land heats faster than the ocean, causing a breeze blowing off the ocean toward land. At night, the land cools, and the wind blows back toward the ocean.

Mechem and his colleagues describe the wave movement as what it's like to be floating on a raft in the ocean far away from the shore, where you're bobbing up and down as the waves roll by.

"Air comes off the continent, interacts with the air over the ocean, and excites these waves, which move through the cloud field, promoting mixing and enhanced cloud evaporation," he said.

What makes the findings released in Science today so important, Mechem said, is that it offers some insight into the behavior of these climatologically important, low-lying marine clouds over the southeast Atlantic that have proven challenging to understand.

"We have to know how they will respond to a warming climate," he said. "Will you have more or fewer? This itself is just a natural event, but we'll be trying to go back and see if there's any trend in the number of these events."

###

The work is supported by the National Science Foundation and the U.S. Department of Energy.

Erinn Barcomb-Peterson | EurekAlert!

Im Focus: The coldest reaction

With ultracold chemistry, researchers get a first look at exactly what happens during a chemical reaction

The coldest chemical reaction in the known universe took place in what appears to be a chaotic mess of lasers. The appearance deceives: Deep within that...

Im Focus: How do scars form? Fascia function as a repository of mobile scar tissue

Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.

Fibroblasts kit - ready to heal wounds

Im Focus: McMaster researcher warns plastic pollution in Great Lakes growing concern to ecosystem

Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.

In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...

Im Focus: Machine learning microscope adapts lighting to improve diagnosis

Prototype microscope teaches itself the best illumination settings for diagnosing malaria

Im Focus: Small particles, big effects: How graphene nanoparticles improve the resolution of microscopes

Conventional light microscopes cannot distinguish structures when they are separated by a distance smaller than, roughly, the wavelength of light. Superresolution microscopy, developed since the 1980s, lifts this limitation, using fluorescent moieties. Scientists at the Max Planck Institute for Polymer Research have now discovered that graphene nano-molecules can be used to improve this microscopy technique. These graphene nano-molecules offer a number of substantial advantages over the materials previously used, making superresolution microscopy even more versatile.

Microscopy is an important investigation method, in physics, biology, medicine, and many other sciences. However, it has one disadvantage: its resolution is...