August 24, 2017

Huskers use eclipse to study impacts of rapid atmospheric changes

A University of Nebraska-Lincoln weather drone flies into the atmosphere during the solar eclipse Monday, Aug. 21, 2017.
Carrick Detweiler/University of Nebraska-Lincoln

Carrick Detweiler/University of Nebraska-Lincoln
A University of Nebraska-Lincoln weather drone takes flight during the solar eclipse Monday.

What would happen to the atmosphere if a natural or man-made disaster suddenly shut off the sun’s radiation on Earth?

Research performed by University of Nebraska–Lincoln scientists during the Aug. 21 eclipse is adding concrete data to this mostly abstract puzzle.

While millions of Americans had their eyes trained on the celestial phenomenon, a team led by Husker scientists Adam Houston and Carrick Detweiler spent the day northwest of Beatrice studying the atmospheric response to a sudden loss of sunlight. The eclipse was a rare opportunity for the research.

“Theoretically, we had an idea of what should happen, but it’s never actually been measured,” Houston said. “This can show if and how the atmosphere changes very rapidly, and help our understanding of how the atmosphere responds when it is perturbed in a significant way.”

Houston, an associate professor of earth and atmospheric sciences, said having data from such an extreme occurrence could allow for better predictions of the possible effects of disasters from very severe weather to a nuclear attack.

“It’s an end member, which is really important to the overall insight into the behavior of the atmosphere,” Houston said. “Science can go from there in mapping out the spectrum of possibilities based on length of time and severity of obscuration of the sun.”

The research team — which included Nebraska undergraduate and graduate students, a researcher from the National Oceanic and Atmospheric Administration and a scholar from Oklahoma State University — focused on the low-level jet stream. Low-level jet streams form when the surface rapidly cools and the air several hundred to several thousand feet above the surface no longer feel the effects of friction. Data were collected from weather drones, weather balloons and surface observations recorded by the Nebraska-engineered Integrated Mesonet and Tracker, a vehicle with mobile meteorological sensors.

Low-level jet streams typically develop gradually, over several hours at nightfall. Houston said they wanted to know if a low-level jet stream could form quickly, within the duration of an eclipse. Low-level jet streams can feed into large, severe storms, making them worse. In another example of their effects, low-level jet streams can cause severe turbulence for air travelers.

The team will continue analyzing the data collected over the next few months, but early examinations did show a nine-degree fall in temperature and surface winds calmed.

Viewers of the eclipse likely noticed these changes, too, in the form of humidity, Houston said. As the eclipse reached totality, the relative humidity rose because of the drop in temperature and the calming of surface winds.

“It felt muggy very suddenly,” Houston said.

The team stayed on site from 10 a.m. until after sunset, gathering data through each phase of the eclipse and at nightfall. The team recorded 223 minutes of data during 13 flights.

The eclipse was also another opportunity for Houston and Detweiler, associate professor of computer science and engineering, to use the drones they have designed through CLOUD-MAP, a project to design and manufacture weather drones to revolutionize weather data collection. The project, which is funded by the National Science Foundation, is in its third year.

Detweiler is also co-director of the Nebraska-based NIMBUS Lab, through which researchers work to design and fly more capable and dependable unmanned aerial vehicles.