Mobile radars, in a meteorological context, are Doppler weather radars affixed to vehicles (or aircraft) for academic or military research. In the mid-1990s, mobile weather radars were designed and created with the goal to study atmospheric phenomena.

History

Transportable weather radars have been used on dozens of scientific and academic research projects from their invention in the 1950s. A problem facing meteorological researchers was mesonets (themselves developed to fill in gaps between widely spaced weather stations) and other ground-based observation methods were often deployed deployed too slowly to accurately and sufficiently completely record significant atmospheric phenomena. In 1993, the Electra Doppler Radar (ELDORA) system was created, consisting of a dual-beam radar mounted on top of a Lockheed P-3 Orion aircraft. The system was designed to provide high-resolution measurements of characteristics of very large storms when ground-based radar cannot.

Between 1994-1995, the initial Doppler on Wheels (DOW) was constructed and was deployed for the first time at the end of the VORTEX1 Project. The DOW was developed by Joshua Wurman and collaborators to obtain recordings within tornadoes and their vicinity to augment the mobile mesonets which had been developed to place observations directly where needed around storms instead of relying on storms to pass over fixed mesonet or other observation sites. The Doppler on Wheels led to several scientific breakthroughs and theories regarding tornadoes and tornadogenesis, such as how tornadoes work within their life cycles and how tornadoes form. The DOWs led to the “first tornado wind maps, measurements of an axial downdraft and lofted debris, multiple vortices, winds versus damage and surface measurement intercomparisons, winds as low as above ground level (AGL) and low-level inflow, 3D ground-based velocity track display (GBVTD) vector wind field retrievals, rapid evolution of debris over varying land use and terrain, documentation of cyclonic/anticyclonic tornado pairs, and documentation of varied and complex tornado wind field structures including multiple wind field maxima and multiple vortex mesocyclones, downward propagation of vorticity and an extensive climatology of tornado intensity and size revealing, quantitatively, that tornadoes are often much more intense and larger than indicated by damage surveys.”

In 2011, Howard Bluestein, a research professor at the University of Oklahoma (OU), led a team to develop the Rapid X-band Polarimetric Radar (RaXPol). In 2013, researchers published at the American Meteorological Society (AMS) that RaXPol was created because “the need for rapidly scanning weather radars for observing fast-changing weather phenomena such as convective storms, microbursts, small-scale features in hurricanes, and the process of convective development has been well established” throughout history. This included publications by the National Center for Atmospheric Research (NCAR) in 1983, research by several scientists published in 2001, and published research by the U.S. federal government in 2012. The United States Department of Defense gave the University of Oklahoma over $5 million (2019 USD) in the development of new mobile radars, which were set to be used by the United States Navy.

In 2023, the University of Oklahoma, along with the National Severe Storms Laboratory (NSSL) developed and deployed the first ever fully digital mobile phased array radar, Horus.

List of notable observations

Several tornadoes throughout the last few decades have been observed by various mobile radars. However, only the most notable ones are used for academic research and subsequently published. This is a list of known tornadoes which were observed by mobile radars.

1990–1999 Official rating Date Location Minimum peak wind speed Maximum peak wind speed Highest confirmed peak wind speedF4 Red Rock, Oklahoma A University of Oklahoma chase team headed by Howard Bluestein utilized mobile doppler weather radar to analyze the tornado. The radar measured peak winds of between above the surface. According to the Oklahoma Mesonet, winds as high as were possibly measured. At the time, this represented the strongest winds ever measured by radar, including the first measurements of F5 intensity winds.F3May 16, 1995Hanston, Kansas As part of VORTEX-95, Doppler on Wheels 1 deployed west of Hanston, KS and scanned an F3 tornado for 45 minutes. DOW 1 recorded a peak ground-relative wind speed of at a range of 13 km. This is the first tornado ever scanned by a Doppler on Wheels vehicle. F2June 2, 1995Dimmitt, Texas A Doppler on Wheels vehicle recorded a peak ground-relative wind speed of . Peak velocity differences (ΔV) recorded at an altitude of around 60 meters reached .F2 McLean, Texas F2 F0 F4 F0 A cyclic supercell near McLean, Texas produced five tornadoes, all of which were observed by ELDORA aircraft. The F4 tornado was recorded to have winds.F4 Spencer, South Dakota A Doppler on Wheels recorded winds of "well below" above the ground level, "perhaps as low as above the radar level". The Doppler on Wheels also recorded a confirmed five-second wind speed average of .F4 Mulhall, Oklahoma A Doppler on Wheels documented the largest-ever-observed core flow circulation with a distance of between peak velocities on either side of the tornado, and a roughly width of peak wind gusts exceeding , making the Mulhall tornado the largest tornado ever measured quantitatively. The DOW measured a complex multi-vortex structure, with several vortices containing winds of up to rotating around the tornado. The 3D structure of the tornado has been analyzed in a 2005 article in the Journal of the Atmospheric Sciences by Wen-Chau Lee and Joshua Wurman. In 2024, it was published that the radar did measure winds of approximately approximately above the radar level.F5 Bridge Creek, Oklahoma In 2007, Joshua Wurman along with other researchers, published that a Doppler on Wheels recorded approximately above the radar level. In 2021, Wurman along with other researchers, revised the data using improved techniques and published that the Doppler on Wheels actually recorded in the tornado.

2000–2009 Official rating Date Location Minimum peak wind speed Maximum peak wind speed Highest confirmed peak wind speedF0 Crowell, Texas F0 F0 Three F0 tornadoes were observed by Doppler on Wheels near Crowell, Texas on April 30, 2000.F1 Oklaunion, Texas A Doppler on Wheels observed this F1 tornado.F2 Geary, Oklahoma A Doppler on Wheels recorded a peak wind gust of at above the ground level.F1 Calumet, Oklahoma A Doppler on Wheels observed an anticyclonic F1 tornado near Calumet, Oklahoma.F1 Truscott, Texas A Doppler on Wheels observed the tornado and recorded a peak wind speed of .F3 Vera, Texas A Doppler on Wheels recorded a peak wind speed of about above the ground level.F0 Bomarton, Texas A Doppler on Wheels recorded a peak wind speed of about above the ground level.F2 Clairemont, Texas A Doppler on Wheels observed the tornado through its entire life. The radar recorded winds of , , and at various heights ranging from .F0 Trego Center, Kansas A Doppler on Wheels observed the tornado in an open field.EF5 Greensburg, Kansas An X-band mobile radar owned by the University of Massachusetts (UMass X-Pol) observed the tornado for roughly 34 minutes after its birth. Recorded winds "exceeding 80 m/s" (179 mph; 288 km/h) were noted roughly 1.5 km above the radar level.EF2 Goshen County, Wyoming Multiple Doppler on Wheels trucks observed the entire lifecycle of an EF2 tornado in Goshen County, Wyoming. The Rapid-Scan DOW radar observed a peak wind speed of at above the ground level.

2010–2019 Official rating Date Location Minimum peak wind speed Maximum peak wind speed Highest confirmed peak wind speedEF5 Hinton, Oklahoma RaXPol recorded a wind gust of about above the radar level. However, this data was later revised to be at above the radar level.EF4 Rozel, Kansas A Doppler on Wheels recorded "near surface" winds of between .EF2 Clearwater, Kansas A Doppler on Wheels recorded winds of at above the ground level.EF5 Moore, Oklahoma A PX-1000 transportable radar unit operated by University of Oklahoma's Advanced Radar Research Center was used to observe the path of the tornado through Moore, with researchers detailing a "loop" in the path near the Moore Medical Center as a "failed occlusion".EF3 Bennington, Kansas A Doppler on Wheels recorded winds of approximately above the ground level.EF3 El Reno, Oklahoma A Doppler on Wheels recorded winds between at or less than above the radar level in a suction vortex inside the tornado. This was later revised by the Doppler on Wheels team to . In 2015, Howard Bluestein, along with other researchers, reported that the radar did capture at least a moment of winds of .EF3 Sulphur, Oklahoma A Doppler on Wheels operated by the Center for Severe Weather Research recorded winds of at above the radar level.EF2 Dodge City, Kansas While a Doppler on Wheels was observing the tornado, it documented winds of , which increased to at least over a span of 21 seconds. These winds lasted less than one minute.EF2 Mangum, Oklahoma The University of Oklahoma's RaXPol and a Doppler on Wheels truck both observed this tornado. RaXPol recorded a maximum VROT of , while DOW7 recorded peak winds of ~

2023 Official rating Date Location Minimum peak wind speed Maximum peak wind speed Highest confirmed peak wind speedEF4 Rolling Fork, Mississippi At least two mobile radars on the PERiLS Project observed the violent EF4 tornado at a height of above the radar level.

2024 Official rating Date Location Minimum peak wind speed Maximum peak wind speed Highest confirmed peak wind speedEF3 Harlan, Iowa A Doppler on Wheels recorded a wind gust of ~ about above the radar level. Peak ground level wind speed was estimated around .EF2 Dexter, Kansas EF1 A Doppler on Wheels observed an EF2 and an EF1 tornado near Dexter, Kansas.EF2 Custer City, Oklahoma A Ka-band mobile radar unit from Texas Tech University recorded a 0-second gust of 87.9 m/s.EF4 Greenfield, Iowa ≥A Doppler on Wheels recorded winds of approximately above the radar level. Following calculations to more accurately determine peak wind speeds, it was published that ground-relative winds of could be observed briefly to the immediate east of the main circulation.EF2 Temple, Texas A Doppler on Wheels observed an EF2 tornado near Temple, Texas.EF2 Duke, Oklahoma & Olustee, Oklahoma Two Doppler on Wheels scanned a large and long-lived EF2 tornado near Duke, Oklahoma. A mobile radar from Texas Tech University recorded winds of less than above the surface.EFU Windthorst, Texas The University of Oklahoma’s RaXPol observed and documented a tornado near Windthorst, Texas.

See also Convective storm detection

References