Phased array radar technology to deploy on research aircraft

Phased array radar beams can be directed and controlled to continuously scan severe storms.

BOULDER, Colorado — When a tornadic supercell thunderstorm forms on the eastern plains of Colorado, meteorologists use a Doppler radar to get critical scans and analyze the storm’s dangerous potential.  

The radar beam is a radio wave that comes out of a spinning antenna. It reflects off of precipitation and returns to the transmitting site, where it’s translated into an image of the storm.

It scans the storm about every six minutes, because that’s how long it takes for the antenna to rotate 360 degrees. 

“We know tornadic storms can evolve rapidly, so six minutes is like an eternity for a tornado forecast,” said Wen-Chau Lee, a senior research scientist at the National Center for Atmospheric Research (NCAR). 

Lee is developing a new technology called phased array. It’s actually been used by the military for decades to detect enemy missiles and operatives, but it has not yet been applied to the weather community. 

A phased array system would still send out a radio wave transmission and measure the reflection, just like NEXRAD Doppler radars that are currently used by the National Weather Service, but they would not need a parabolic antenna. 

A computer system electronically controls the beam so it can scan in any direction, at any time, for as long as needed — never missing a moment of tornado development.  

“The phased array radar can focus on a specific feature rather than to scan around and around and around in order to sample that feature,” Lee said. “So it allows you to capture a more complete picture of storm formation, and drastically reduces the time it takes to do it.” 

Lee said phased array will likely become the standard for ground-based weather radar, but first it will be installed on NCAR’s C-130 aircraft. The technology itself will get evaluated while scientists use it for research.   

“It will be a great advantage for scientists to fly directly to storms and scan them at close range in detail that they have never been able to use,” he said. 

He said another capability of phased array radar is something called dual polarization scanning. It allows meteorologists to see the three-dimensional microphysics of cloud particles. Ground-based Doppler has that ability, but radar beams lose some of their integrity with distance. 

And with aircraft, scientists can target specific storms instead of settling for whatever might come close to a ground-based radar. In addition, many of the storm systems like nor’easters, atmospheric rivers and hurricanes form over the oceans, where ground-based radars are ineffective. 

He said that even the NOAA and Air Force Hurricane Hunter aircraft only have tail Doppler radars that don’t have dual polarization capabilities. 

“If they could adapt the airborne phased array radar technology, I believe it would be a game changer for hurricane forecasts in the U.S.,” Lee said. 

NCAR’s airborne phased array project received $91.8 million in funding from the National Science Foundation and is slated to begin in the spring of 2028. It is expected that scientists will soon begin to pitch their ideas for groundbreaking new storm research. 

“It’s like a dream come true for me,” Lee said. “Not just excited about the technology, but it’s excitement in the potential of using this technology to advance science and ultimately save lives and properties.” 

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