DWIGHT — Perched atop a hill in southeastern Butler County, surrounded by head-high corn and ever-growing soybeans that stretch as far as the eye can see, Doppler radar scanned the skies.
Mounted on the back of a truck, the Doppler on Wheels (DOW) tracked a thunderstorm forming far off to the northwest, one that would soon grow and plow across the plains Wednesday night, drenching most of eastern Nebraska.
Equipped with computers, antennae and other technology, the DOW was also watching a weather balloon travel into the upper reaches of the troposphere, the lowest layer of the Earth’s atmosphere, as it continued recording data nearly 100,000 feet above the ground.
The balloon is one of hundreds that will ascend into the blue through the end of the month, part of an expansive study led by the University of Nebraska-Lincoln in cooperation with three other universities funded through the National Science Foundation.
The Great Plains Irrigation Experiment, or GRAINEX, seeks to understand how irrigation practices across 3,600 square miles in southeastern Nebraska may affect weather and climate, particularly during the peak irrigation months of June and July.
“Land cover anywhere plays a very important role in the climate,” said Rezaul Mahmood, lead researcher and director of Nebraska’s High Plains Regional Climate Center at the University of Nebraska-Lincoln’s School of Natural Resources.
Cities built on concrete and asphalt typically experience temperatures 10 to 12 degrees Fahrenheit higher than the surrounding rural areas, Mahmood said, while the evapotranspiration of water from soil and crops is a driver of the humid conditions known as the corn sweats.
Mahmood said increased irrigation practices in Nebraska, which is one of the highest irrigated regions on the planet, have turned the eastern half of the state into the perfect laboratory to study the phenomenon.
Previous studies have suggested irrigated fields hold 36 percent more energy compared with grasslands of the same size, he said. Evapotranspiration, The natural process of plants drawing water from the ground, and the water evaporating from its leaves, injects that energy into the atmosphere.
“Our goal is to understand how irrigation is impacting the lower part of the atmosphere,” Mahmood said.
To do that, GRAINEX is taking a snapshot of that atmospheric layer every two hours from sunup to sundown from three mobile locations as well as two permanent locations, one east of Lincoln and the other in York.
At the DOW truck northwest of Dwight, junior meteorology majors Jamie Foote and Dan Popelka began preparing the first weather balloon of their shift for launch, filling it with helium to 200 pounds per square inch and tying a radiosonde to it shortly before 2 p.m.
On the hour, Popelka and researchers at the other sites simultaneously released their balloons, aiming to record atmospheric temperature, dew point, relative humidity, wind speed and direction above the corn and soybean fields below, and beam the data back to Earth.
“We are looking to get a vertical profile of the atmosphere,” said Foote, of Arvada, Colorado, who explained how a computer on the receiving end converted the data into a skew-T diagram used to analyze and predict the weather.
Much of the data compiled inside the DOW truck and later backed up onto servers at the university put lessons the UNL students learned in their meteorology classes into a practical framework, Popelka said.
"It's interesting to see this out in the field and how it applies to real-life research," the Omaha native said.
In both this intensive observation period, as well as a previous two-week period in June, more than 600 balloons will rise into the air to develop an atmospheric profile to be combined with other data being collected.
Together with the balloon sites, GRAINEX also records the field conditions from 12 stations — six in irrigated fields and six in non-irrigated fields — while also recording the weather at ground level from 75 weather stations scattered across the area.
Mahmood said most of the three-year NSF grant will be dedicated to poring over data, teasing out trends in atmospheric conditions and comparing weather patterns over irrigated fields to non-irrigated land.
UNL is working with Western Kentucky University, the University of Alabama at Huntsville and the University of Colorado Boulder on the project, as well as the National Center for Atmospheric Research and the Center for Severe Weather Research on the project.
Other agencies also are adding research expertise — NASA is recording available soil moisture from a plane flying high above the Great Plains — or acting as liaisons on the ground, including the state Department of Natural Resources and the local Natural Resource Districts, which have been working with local landowners, Mahmood said.
Researchers will put the data onto the public domain in about six months, he added, even as they continue drilling into it to improve existing forecasting models that calculate probable conditions using thousands of mathematical equations used by meteorologists.
Or, at the very least, Mahmood said the new atmospheric profile could better inform the human element in weather forecasting.
“If you know the local conditions that may not have been captured in past models, that can give an additional edge,” he said.