Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

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

23.07.2018

If you could hover far above the southeast Atlantic Ocean, particularly during the months of April through June, on many days you will likely witness a sharp line of clearing moving east-to-west and eroding large regions of low cloud typically present over the region.

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.

Media Contact

Erinn Barcomb-Peterson
ebp@ku.edu
785-864-8858

 @KUNews

http://www.news.ku.edu 

Erinn Barcomb-Peterson | EurekAlert!

More articles from Earth Sciences:

nachricht New studies increase confidence in NASA's measure of Earth's temperature
24.05.2019 | NASA/Goddard Space Flight Center

nachricht New Measurement Device: Carbon Dioxide As Geothermometer
21.05.2019 | Universität Heidelberg

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Colliding lasers double the energy of proton beams

Researchers from Sweden's Chalmers University of Technology and the University of Gothenburg present a new method which can double the energy of a proton beam produced by laser-based particle accelerators. The breakthrough could lead to more compact, cheaper equipment that could be useful for many applications, including proton therapy.

Proton therapy involves firing a beam of accelerated protons at cancerous tumours, killing them through irradiation. But the equipment needed is so large and...

Im Focus: New studies increase confidence in NASA's measure of Earth's temperature

A new assessment of NASA's record of global temperatures revealed that the agency's estimate of Earth's long-term temperature rise in recent decades is accurate to within less than a tenth of a degree Fahrenheit, providing confidence that past and future research is correctly capturing rising surface temperatures.

The most complete assessment ever of statistical uncertainty within the GISS Surface Temperature Analysis (GISTEMP) data product shows that the annual values...

Im Focus: The geometry of an electron determined for the first time

Physicists at the University of Basel are able to show for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.

The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a quantum computer. Controlling and switching this spin or...

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

AI and high-performance computing extend evolution to superconductors

27.05.2019 | Information Technology

Meteor magnets in outer space

27.05.2019 | Physics and Astronomy

Coat of proteins makes viruses more infectious and links them to Alzheimer's disease

27.05.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>