When it comes to Doppler weather radar, scientists with NOAA National Severe Storms Laboratory wrote the book. Literally. Publications authored and co-authored by researchers at NSSL and the Cooperative Institute for Mesoscale Meteorological Studies expanded knowledge on radars and provided strategies used by weather forecasters today.
After more than three decades, those scientists have done it again. A new book by CIMMS Senior Research Scientist Alexander Ryzhkov, and co-authored by NSSL Senior Scientist Dusan Zrnic, highlights the biggest technological upgrade to Doppler radars since they were first installed — dual-polarization technology.
The book, “Radar Polarimetry for Weather Observations,” published by Springer Nature, offers an array of information on weather radar polarimetry. Polarimetric radar — and polarimetry — improves the accuracy of precipitation estimates, detects aviation hazards, can identify precipitation types, and can spot many other items such as bats or even tornado debris.
In addition to connecting processes responsible for the development and evolution of the bulk of clouds’ physical properties, the publication also provides up-to-date polarimetric methodologies.
The publication will appeal to practicing radar meteorologists, hydrologists, microphysicists, and modelers who are interested in the bulk properties of hydrometeors and quantification of these with the goals to improve precipitation measurements, understanding of precipitation processes, or model forecasts.
Radars are a vital tool for weather forecasters because they provide a detailed picture of storms as they’re happening. A new radar technique is improving the picture for forecasters, helping them provide more accurate information about rain and snow storms.
“Through this unique collaboration paradigm, we’ve proven that scientific partnerships can transcend geographical, political and proprietary boundaries,” said Sebastian Torres, CIMMS researcher leading NSSL’s Advanced Radar Techniques Team. “The atmosphere knows no geographical boundaries. Better forecasts in the UK can provide improved information to the United States, and vice versa, as we continue to build partnerships to help save lives, property and minimize the economic impact of severe weather in the U.S.”
Weather radars often pick up noise from various sources like the sun or man-made devices similarly to how a radio or television sometimes retrieve a static signal. The RBRN analyzes radar beam data in real-time and performs several tests to ensure the noise can be detected and measured.
“Accurate measurement of noise on weather radars is critical as it impacts the accuracy of radar data and plays a key role in data quality control,” Torres said.
In addition, a portion of energy from the radar beam may also be absorbed by particles in its path before the radar beam energy is returned.
“This weakens the echoes from locations far from the radar and gives the wrong impression that storms in these locations are weaker than they truly are,” Torres said. “Because the particles in the radar beam path emit noise, the noise measured by RBRN can be used to correct for the weakening or attenuation of echoes as the radar beam intersects storms. The operational RBRN estimator significantly improves the quality of radar data, especially for weak returns associated with snow storms and gust fronts.”
Reducing and accurately measuring contamination from the noise in the radar data equates to better information and more accurate forecasts for the public.
The RBRN was originally developed by CIMMS Researcher Igor Ivic and became operational in the U.S. NEXRAD radar network in 2014.
Radar research at the NOAA National Severe Storms Laboratory has taken another step forward. The Advanced Technology Demonstrator is installed at the National Weather Radar Testbed facility and will become fully operational in 2019.
The Advanced Technology Demonstrator, or ATD, is the first full-scale, S-band, dual-polarization phased array radar built from the ground up and designed specifically for use as a weather radar.
A phased array radar is able to steer the radar beam electronically left-to-right and up-and-down while the antenna remains stationary. The ATD has a flat, or planar, antenna comprised of 76 panels with 4,864 radiating elements.
In addition, the ATD features dual polarization technology developed at NSSL and recently added to WSR-88D radars, also known as NEXRAD, throughout the country. The ATD is adding dual polarization technology to phased array technology, combining the benefits of both. The new radar will feature dual-polarization’s ability to show the size and shape of precipitation, and the phased array’s faster updates.
The radar will be used for meteorological studies and to help researchers evaluate polarimetric performance of a planar phased array radar.
NOAA National Severe Storms Laboratory Researcher Sean Waugh will collect weather data in the path of Hurricane Harvey Friday to record how the landfalling hurricane changes as it develops.
The first major hurricane forecast to make landfall in the Gulf Coast in 12 years provides an opportunity to study its development and any potential development of tornadoes.
“While tornadoes are relatively rare in environments associated with landfalling hurricanes, if they occur they can have large impacts,” Waugh said.
Waugh will use a truck with roof mounted instruments called a mobile mesonet to record observations of Hurricane Harvey for an extended period of time. The instruments and weather balloons will record rain, wind and temperature. He will work with scientists from The University of Oklahoma College of Atmospheric and Geographic Sciences. The team is utilizing the university’s Cooperative Institute for Mesoscale Meteorological Studies SMART radar truck.
Researchers will monitor how the hurricane’s structure changes during landfall as well as temperature changes and wind on the surface. Scientists will test a new instrument developed at NSSL that measures rain size and distribution to help with flood forecasts. Information gathered will be shared with National Weather Service forecasters.
NOAA NSSL and partners are studying the development of tornadoes in the Southeast U.S. in order to improve their prediction through VORTEX-Southeast.
A new research project is already helping save lives and property with early flood notification after a stream in southern Oklahoma rose 10 feet in one hour.
Jonathan J Gourley, research hydrologist with the NOAA National Severe Storms Laboratory, said the project will demonstrate the use of remote-sensing technology for better flood detection and improve downstream predictions by models. Researchers will deploy 14 stream radars throughout the United States that utilize remote sensing to measure the speed, depth, and flow rates in streams.
NSSL is leading several remote sensing in streams projects, known as Automated NonContact Hydrologic Observations in Rivers, or ANCHOR, with funding from NOAA’s Joint Technology Transfer Initiative. This part of the project is with The University of Oklahoma Cooperative Institute for Mesoscale Meteorological Studies and the project principal investigator Danny Wasielewski, an electronics engineer with OU CIMMS.
Walking through patches of poison ivy and trudging through deep mud, the research team installed the project’s second radar above a creek near Mill Creek, Oklahoma, in late July. It will monitor the stream’s water speed and depth, along with how quickly the water may rise during a hazardous weather event, and notify researchers and local stakeholders of the observed changes.
The first stream radar was deployed in April in Falls Creek near Davis, Oklahoma, and near Falls Creek camp, an area that has more than 55,000 visitors participating in youth camps and conferences each summer. As many as 7,500 campers may be downstream at any moment.
Within a few weeks, the Falls Creek installation provided useful data to the ANCHOR team.
The radar was in place taking measurements as the water transformed from a trickling stream to a raging river on May 19. Gourley received a notification indicating flash flood conditions, triggered by a sudden increase in the stream’s water flow. He cross-checked the project information with NSSL’s Flash Flood Forecast System and concluded flash flood conditions were occurring.
Based on this information, he notified Falls Creek officials, advising them to take precautions. One hour after the notification the river rose 10 feet. Fortunately, no visitors were at camp that week.
“The sensor provided real time information and text alerts were issued indicating an impending threat,” he said.
The event itself was rare, and measuring it was even more unprecedented.
“Capturing an event of this magnitude just a matter of weeks after we installed the instrument is very rare, equivalent to finding a needle in a haystack,” Gourley said.
The increase in velocity indicated by the radar was a major insight in itself. The stream’s velocity increased an hour before the depth began to rise, providing additional time to respond to an impending flash flood.
“When we later went out, we saw the radar was damaged from debris flowing down river during the event created by a loss of soil composition,” Gourley said. “A tree fell on top of one radar cable and tore it from the mount, but it continued to operate.”
Deploying radars to measure water height, in combination with text alerts and notifications may impact water resource management practices and help save more lives from the number one severe weather killer – flooding.
The system being demonstrated for operational use during the two-year JTTI-funded project may offer a more cost-effective and accurate solution for estimating streamflow and flooding conditions than what is currently being used in the United States. Gourley said conventional gauging can be costly and the amount of conventional gauges used is generally going down because of the time and resources required.
ANCHOR’s team continues scouting for new radar installment locations. Installations will take place through 2017 with results expected in early- to mid-2018.
The National Severe Storms Laboratory is saddened to announce the passing of Jean “J.T.” Lee, a pioneer who managed NSSL’s aircraft program when it began, leading to better weather-related safety.
Lee was a scientists at NSSL for 42 years, discovering and documenting correlations between weather radar and turbulence hazards to aircraft. This work began at the Weather Bureau’s National Severe Storms Project based in Kansas City, Missouri, then was part of the team who moved to Norman to start the National Severe Storms Laboratory in the early 1960s.
During 2004, Lee was interviewed about his job and why he enjoyed working at NSSL.
“I found it fascinating,” he said. “The people we worked with were devoted and many times we weren’t 8 to 5 but 8 until whenever the situation stopped and that would be midnight sometimes,” he said. “There was real camaraderie.”
“The Air Force at that time was beginning to have problems with their jet aircraft,” Lee said during an interview about NSSL’s 40th anniversary. “They were interested in what was the weather above thunderstorms and how high did thunderstorms extend. Our penetration work was around 30,000 feet with the aircraft and we were the first ones to do supersonic penetrations. I feel the greatest accomplishment here was we were able to provide the design of safety procedures for the safety of flight.”
His work contributed to several Federal Aviation Administration guidelines, including a memorandum to the FAA Wind Shear Program Office in 1976 suggesting the usage of anemometers to provide instant reports on winds near airports.
Lee wrote more than 50 research articles in journals on aviation radar interpretation, aircraft turbulence and wind shear, and Doppler radar studies. He received several awards, including the Losey Atmospheric Sciences award in 1981 for his invaluable contributions to flying safety. The award was one of seven presented by the American Institute of Aeronautics and Astronautics. He was also honored in 1982 with the NASA Group Achievement award for MSFC Doppler Lidar 1981 flight experiments.
The national weather radar system used throughout the United States by NOAA National Weather Service forecasters to “see” weather across the country is unique because it can be upgraded and modified with the newest capabilities, unlike other systems worldwide.
The U.K. Met Office operated a radar system that did not allow changes and was considered a “commercial off-the-shelf solution.”
“Most weather services in the world purchase radar systems from companies and in those systems, the signal processor is typically a black box,” said Sebastian Torres, senior research scientist with OU CIMMS and NSSL. “The signal processor is a key component in all weather radar systems. Its job is to convert echoes received by the radar into weather images. It’s something most weather services don’t really have access to. They know how it works but they can’t change or improve anything.”
The U.K. Met Office decided to build its own signal processor for their radar systems. This allows a similar degree of flexibility to that of the NEXRAD radars, also known as the WSR-88D (weather surveillance radar-88 Doppler), operated in the United States. NOAA offered some of its tested techniques to the U.K. Met Office and in return received access to valuable data it could use for future research and operations.
Inside every NEXRAD radar is a rotating parabolic antenna. As the antenna rotates, it travels up and around while sending out pulses of electromagnetic energy. When radars send and receive these pulses, buildings and other structures may obstruct the radar’s view, contaminating the storm data.
To help keep unwanted objects from impacting storm data, Torres and fellow CIMMS Researcher David Warde developed two complementary signal-processing techniques for the WSR-88D. One technique, called CLEAN-AP, or Clutter Environment Analysis using Adaptive Processing filter, removes unwanted radar echoes from objects on the ground. The other one, called WET or Weather Environment Thresholding, intelligently decides when the CLEAN-AP filter should be applied. This prevents slow-moving storms from being confused with stationary objects.
“The goal of CLEAN-AP and WET is to clean the data as much as possible so the forecasters have the best data available to make warnings and forecasts,” Torres said.
Through collaboration with the U.K. Met Office, who implemented CLEAN-AP and WET, the techniques were fine-tuned and improved. Both techniques are being transferred to the NOAA National Weather Service, and CLEAN-AP is licensed by OU to U.S. weather radar manufacturer Baron.
Another CIMMS Researcher, Igor Ivic, developed a third product transferred to the U.K. called the Radial-by-Radial Noise Estimator. RBRN improves the quality of radar data by removing “noise,” the radar equivalent of radio static or television static. It was implemented on the U.S. NEXRAD network as part of ongoing research-to-operations efforts at NSSL and CIMMS.
“If you have noise and you can remove it from the radar returns, then you get just the signal, and that can be used to get better quality data,” Torres said.
Torres called the collaboration a “win-win” situation because the information exchange, as well as the new technologies and techniques that have been developed are good for both the U.S. and U.K.
NSSL scientists won’t have to travel far this year for the AMS Radar Conference! The 37th Conference on Radar Meteorology will be held right here in Norman, Oklahoma, at the Embassy Suites Hotel and Conference Center. The event, which takes place September 14-18, will kick off with an icebreaker reception at the National Weather Center on the University of Oklahoma campus.
Participants are encouraged to sign up for tours of well-known Norman attractions, which will be offered on Wednesday, September 16. Locations open for tours will include the National Weather Center, NOAA’s National Weather Radar Testbed, OU’s Radar Innovations Laboratory, and OU’s Bizzell Library. On the tour of the National Weather Center, participants will see several NOAA facilities, including the Hazardous Weather Testbed, National Weather Service Norman forecast office, and the Storm Prediction Center. The tour of NOAA’s NWRT will offer the chance to learn firsthand how NSSL researchers test nd evaluate phased array radar.
Weather radar research is a key part of NSSL’s mission in support of the NOAA National Weather Service (NWS). This week, NSSL/CIMMS scientists will share the latest in weather radar research at the American Meteorological Society’s 2013 Conference on Radar Meteorology in Breckenridge, Colo.
Phased array radar research presentations include:
An overview of the latest improvements to the National Weather Radar Testbed
Phased Array Radar (NWRT PAR) capabilities to demonstrate Multi-function
Phased Array Radar (MPAR) program weather and aviation requirements
How NWS forecasters’ responded to rapid, adaptive phased array radar sampling and if it increased their ability to effectively cope with tough tornado
New techniques to increase the NWRT PAR scan rate and reduce observation
NWRT PAR observations of microburst events
A method to detect and characterize storm merges and splits using rapidly updating NWRT PAR observations in thunderstorm models
NSSL/CIMMS researchers also work with current weather radars in operation and will present:
A new algorithm that combines output from a forecast model with dual-polarized radar data to more accurately estimate what winter weather is occurring between the lowest scan of the radar and the ground.
A study of how NSSL’s products that estimate precipitation amounts improved using dual-polarized radar data
Evaluation of existing hail size estimation algorithms
Crowdsourced reports precipitation types at the ground using the “meteorological Phenomena Identification Near the Ground” (mPING) smart phone app
Development of a database of U.S. flash flood events using NSSL’s Severe Hazards Analysis and Verification Experiment, and mPING reports
Improvements in radar wind data quality control
Other presentations include mobile radar observations of a tornadic supercell and rainfall in the Mediterranean region and airborne radar observations of precipitation in the Indian Ocean.
On both May 19 and May 20, 2013, NSSL researchers collected data on storms that produced tornadoes using both the NWRT Phased Array Radar (PAR), and the mobile dual-polarized radar. The NWRT PAR can scan the sky in less than one minute, five-times faster than current weather radars. Datasets from the rapidly-updating NWRT PAR will help researchers better understand the evolution of rotating thunderstorms and the tornadoes they produce.
May 19, 2013
The NWRT PAR, a retired Navy surveillance radar adapted for weather, scanned a storm from its first radar echoes through its production of a tornado. When this storm moved out of range, the PAR was directed to scan the tornado that formed in Norman, Okla. through the time the tornado moved into Shawnee, Okla., killing two people. Loops of radar imagery are below with still images following.