Student Todd Murphy teamed with UAH atmospheric science professor Dr. Kevin Knupp to make one of the first comprehensive analyses of cold season supercells using only one Doppler radar with the application of the SDD analysis technique. The SDD technique allows researchers to examine the winds inside supercells in three dimensions.
Doppler radar works by sending a beam of electronic radiation that is tuned to a precise frequency at an object. The beam is then reflected back to a receiver. By using a phenomenon known as the Doppler effect, the frequency of the beam when it went out and the altered frequency of it when it returns can be used to calculate the movement of the object.
When developed in the late 1960s and refined in the 1970s, the SDD analysis used one such radar unit for the data needed to provide insights into the dynamic and thermodynamic quantities of a storm and measure wind speed and direction.
However, the ability of SDD to peer inside super-cells can be limited because the storms first must be close enough to radar facilities to be detectable.
“This is certainly a technique that will only work in certain cases,” Murphy said. He has personally experienced the limitations when attempting to position UAH’s Mobile Alabama X-band (MAX) truck to collect data on approaching storms.
“In the Southeast, with our topography and the trees we have, it is really difficult to position MAX.”
Data from the widespread outbreak of cold season supercell storms on Super Tuesday in 2008 provided an opportunity for Murphy and Dr. Knupp to examine using the SDD technique with readings from single Doppler radar facilities.
Nighttime supercells on Super Tuesday 2008 were so widespread that in Tennessee, one in near Memphis and one near Nashville were close enough to single Doppler radar facilities for information about the storms to be obtained. Murphy and Dr. Knupp subjected the data from those single radar facilities to the SDD analysis technique.
“We were trying to find a new way to look at storms,” said Murphy. “We feel like with this research, we proved that you can use just one radar source and the synthetic dual-Doppler radar technique to retrieve the winds in supercell thunderstorms.
“The SDD technique allows us to retrieve the three-dimensional wind components of a storm,” he said. “It provides us with a lot more insight into what makes up a storm, including data on the vorticity (spin) of a supercell.”
Researchers can see what’s going on inside storms from about 500 meters off the ground and higher, so SDD provides information on the mid- and upper-level factors that are in turn spawning tornadoes on the ground.
“What we are really looking at is the mesocyclone, or the large movements occurring in the storm,” Murphy said. Mesocyclones are huge vortexes of air moving around a vertical axis within a thunderstorm.
Because the radar got better data from the Nashville storm, it was the primary focus of the study. Its structure was very similar to low-top supercells that commonly are spawned as bands surrounding hurricanes, Murphy said.
Murphy’s data also affirmed the importance of strong rear flank downdraft (RFD) in the formation of tornadoes. RFDs are the downdraft winds that occur in the trailing portion of the comma-like hook that is typical of storms that spawn tornadoes.
“Some previous research had shown RFD to be important in tornadogenesis,” Murphy said. “The findings here do agree with the previous research that RFD is important.”
Next, Murphy plans to publish a paper that is a large-scale view of the contributing factors of the Super Tuesday 2008 event as a whole.Dr. Kevin Knupp
Dr. Kevin Knupp | Newswise
05.07.2018 | Institute of Science and Technology Austria
Research project: EUR 3.3 million for improved quality of life in shrinking cities
02.07.2018 | Technische Universität Kaiserslautern
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences