Weather tracking radar network developed

The new 50-foot-tall tower atop Orchard Hill on the UMass Amherst campus houses the prototype unit for a new radar network that can beam into a critical blind spot of the atmosphere that conventional radar systems cannot currently monitor, promising to transform the way human beings monitor weather and track storms.

“The MA1 radar, and the dense network of radars that CASA is developing, are exciting on many fronts,” said Distinguished Professor Jim Kurose, CASA Associate Director. “From a Computer Science standpoint, they represent a new breed of data-driven, networked, sense-and-response systems. The project is intellectually exciting in that it brings together computer scientists, radar engineers, meteorologists, atmospheric scientists, sociologists and end-user specialists.”

As part of a DCAS (Distributed Collaborative Adaptive Sensing) radar network, the unit being tested on Orchard Hill can sense the lower three kilometers of the atmosphere—the crucial area where storms actually form. For the first time, DCAS technology can follow weather disturbances with the accuracy of an eye-witness emergency manager on the ground. When deployed in the field, DCAS radar networks will provide emergency managers with an invaluable new tool to save lives, carry out evacuations, evaluate potential flooding and direct the emergency flow of traffic.

DCAS radar is the brainchild of the National Science Foundation (NSF) funded Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA), a partnership among 19 different institutions including UMass Amherst, the University of Puerto Rico Mayaguez, the University of Oklahoma, Colorado State University, Raytheon, Vaisala, Vieux and Associates, and the National Atmospheric and Oceanic Administration.

The six-foot-tall apparatus sits atop the CASA tower encased in a golf-ball-shaped radome of fiberglass and coated with a hydrophobic substance that repels water, thus protecting the radar from the elements. Its antenna is nearly 50 times smaller than each conventional high-power NexRad system now used by the National Weather Service.

“This step is the verification of our prototype,” says Michael Zink, head of the Technical Integration Thrust for CASA. As soon as the unit proves itself during its test phase, a four-radar DCAS network could be saving lives in the field by this spring in one of Oklahoma’s tornado alleys. The four-node testbed began rising above the southwest Oklahoma plains in January 2006, and will be operational by April of this year. Other test beds will be operated by the CASA collaborators in Colorado and Puerto Rico.

Today’s measurements of the lower three kilometers of atmospheric soup—swirling wind fields and super-cells that spit out tornadoes—are severely limited by existing technology. The system in use today features long-range high-power radars that scan a 200-kilometer radius above cloud level. Their high-power waves shoot straight toward the surrounding horizons, thus the curvature of the planet prevents these units from sensing the lower atmosphere. Current technology is also relatively insensitive to storms, such as tornadoes, after they fall to earth.

DCAS, however, uses large numbers of low-power Distributed nodes with short beams that overcome the earth’s curvature. These tiny DCAS radars are Collaborative in the sense that they can cooperate to target their beams on one weather pattern—a tornado, for instance—thus triangulating on it and following its course with the precision of storm chasers in mobile units. The DCAS nodes are also Adaptive because they’re engineered to be rapidly reconfigured in response to quickly changing weather.

“This will monitor lower-atmospheric weather for 20 miles around,” explains David McLaughlin, director of CASA. “It will allow us to test the functionality of the low-power radar concept, the signal processing, and its communications. It’s the sensing part of the operation.”

DCAS radars are expected to usher in a new era in very low power, very low cost radar designs. “This new radar transmits less than one-tenth the power of a light-bulb,” says doctoral student Francesc Junyent, one of 10 CASA engineers (more than half of them graduate students), who created the first DCAS prototype. “Ultimately, we’ll be able to make these radars using low-cost microwave and digital chips the same way we currently make computer boards.”

The work has been funded by a $17 million NSF grant, $5 million from the Commonwealth of Massachusetts and $18 million from CASA’s industry and university partners. Recent funding includes $2.5 million from the state of Oklahoma, $650,000 from Colorado State University and $100,000 from NASA.

This completed DCAS network will track touched-down tornadoes more precisely than ever before possible, cut down on the high percentage of false alarms and comprehensively map the thermodynamic state of the lower atmosphere. According to CASA consultant Luko Krnan, DCAS networks could even help emergency managers with rainfall and flooding prognostication related to hurricanes such as Katrina.

More on CASA at http://www.casa.umass.edu.