KU News Headlines
LAWRENCE — 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 clouds 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.
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 professor of geography & 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 airflow from land to ocean overnight is triggering atmospheric waves that then …