Will tomorrow’s radars be capable of tracking swiftly changing weather phenomena?
Increasingly severe weather events require cutting-edge technologies to monitor them in real time. Could phased array radars be the key?
Devastating tornadoes, catastrophic floods, in the face of increasingly violent weather events, traditional radars are no longer enough . These new climate challenges are forcing scientists at the National Severe Storms Laboratory (NSSL) to explore phased array radar (PAR), which could revolutionise atmospheric monitoring.
The challenges of traditional radars
For more than 30 years, the NEXRAD (Weather Surveillance Radar, Doppler since 1988) radar network has been at the heart of weather forecasting in the United States . This Doppler radar network detects precipitation, tracks storms, and allows meteorologists to detect tornado warning signs.
However, the scanning time of this radar, which lasts between four and six minutes, constitutes a major limitation: violent phenomena such as tornadoes, flash floods or gusts often evolve in a few seconds, thus escaping the NEXRAD radars and leaving critical “gray zones”.
This lack of responsiveness poses a real safety issue for populations in the event of extreme weather. In addition, the ageing of the NEXRAD system, which is expected to become obsolete in the 2030s, makes it urgent to develop a system capable of providing more frequent and accurate information to monitor the weather in real time.
What is a phased array radar?
Phased array radar (PAR) is based on a radically different technology. Unlike traditional radars that use a rotating antenna, PAR is equipped with a single fixed antenna made up of hundreds or even thousands of elements. Each of these elements can transmit and receive a signal independently, allowing the PAR to electronically control the direction of the radar beam without any part moving .
This grid arrangement allows the PAR to scan the atmosphere at exceptional speed , refocusing its beam in just a few microseconds to capture the slightest atmospheric changes in near real time.
Beamforming: for precision and flexibility
PAR uses an advanced technology called beamforming . Imagine that each element of the radar mentioned above is like a searchlight that can adjust its light to illuminate a specific spot. Thanks to this technology, the radar can focus on specific areas of the atmosphere with great precision , without losing any light.
Thanks to beamforming, the radar can simultaneously analyze several areas of a single storm , or a supercell storm, capturing details invisible to conventional radars.
Beamforming also improves image quality by reducing unwanted signals to deliver sharper data. This multi-target capability, a result of military advancements, gives PAR a significant advantage in meteorology: the ability to monitor and analyze various weather phenomena quickly and accurately .
Real-time monitoring?
PAR’s scanning speed is a major advantage. While NEXRAD takes several minutes to complete a full scan, PAR can do so in less than a minute . This responsiveness is crucial for observing rapidly evolving phenomena such as storms, tornadoes, and flash floods, where every second counts in alerting populations and organising aid.
The flexibility of the PAR, which can focus its observations on a specific area without the need for a full scan , also brings a gain in efficiency. In the event of a storm, the PAR can concentrate its efforts on the most intense part of the storm or reorient itself instantly in the event of a potential vortex.
Application and advantages
In addition, PAR is designed to withstand mechanical failures while providing more dynamic and adaptable coverage. In addition to meteorological phenomena, this technology is widely used in the defense and aerospace sectors for its precise detection capabilities and rapid updates.
For example, phased array radars mounted on military ships can track more than 100 targets at once, demonstrating PAR’s ability to monitor multiple critical weather events simultaneously.
Challenges and prospects for implementation
Although promising, PAR technology has challenges. Its implementation requires complex infrastructure and real-time data processing capacity , since each scan generates a large amount of information.
Furthermore, PAR has a limited coverage angle of approximately 120° , which would require multiple radars to cover large regions. Its development and installation costs are also high , making it difficult to adopt on a large scale in the near term.
However, NSSL researchers are working on deploying PAR by 2040 , to gradually replace NEXRAD. The transition to this technology will require significant financial and technological support, but could prove essential to addressing growing climate challenges.
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