The Union City tornado in 1973 had a signifi cant impact on the history of severe weather research and the development of Doppler weather radar.
Mobile mesonets, or “probes,” made it possible to get close-up data on developing storms during VORTEX.
IPEX – INTERMOUNTAIN PRECIPITATION EXPERIMENT (2000) Scientists studied winter weather in Utah to better understand the structure and evolution of winter storms. Researchers used the data to validate precipitation estimates from radars located at high elevations and to improve forecast models used in mountainous regions. The current generation of mobile Doppler radars are now being used for precipitation and debris fl ow studies in rugged wildfi re burn areas in California.
TELEX – THUNDERSTORM ELECTRIFICATION AND LIGHTNING EXPERIMENT (2003-04) The TELEX team made balloon soundings from a mobile laboratory to measure the electric field profile of thunderstorms. Scientists believe knowledge of how lightning is dependent on storm structure, updrafts, and precipitation will point to new ways for the National Weather Service to use lightning observations to improve forecasts and warnings of hazardous weather.
Field research gives scientists a way to test improvements in forecasting tools, and to validate current theories or propose new ones about how storms develop. Over a span of more than forty years, the tools and techniques for intercepting storms when and where they occur and recording their data have changed dramatically. NSSL field teams now use Doppler radars mounted on trucks, cars with weather instruments on top (mobile mesonets), special cameras, global positioning systems and vehicles for launching weather balloons to observe and record the atmosphere in and around storms. Intercept teams rely on surface observations, satellite data, short-term forecasts, and radar information transmitted to the field in real time, usually from a mobile command vehicle. While research results may take years to analyze, every contribution adds to a larger knowledge base that ultimately makes hazardous weather forecasts and warnings more timely and more accurate.
1970s: observation
The Tornado Intercept Project during the 1970’s marked the beginning of NSSL’s efforts to study storms in the field. Storm intercept teams observed and documented the entire Union City tornado on film. The visual history and damage path were then correlated to specific signatures in NSSL’s experimental Doppler radar data. These unique signatures were later verified by the Joint Doppler Operational Project (JDOP). The radar’s ability to “see” a developing tornado was a major reason the NEXRAD Doppler radar network was created in 1988.
1980s: measurements from the field
During the 1980s scientists began to collect in situ data using instruments carried in storm intercept vehicles. From newly-developed mobile laboratories, scientists were able to document the frequency of in-cloud lightning flashes and confirm positive cloud-to-ground flashes, thought to be associated with tornado development in severe convective storms. Scientists developed a conceptual model of the electrical structure of thunderstorms from rawinsonde data transmitted during mobile balloon launches.
1990s: fully mobile
VORTEX – Verification of the Origin of Rotation in Tornadoes Experiment (1994-95) The VORTEX program was designed to answer questions about the causes of tornado formation. This project was the first to use mobile Doppler radars and mobile mesonets to collect data in the field. Also for the first time, airborne Doppler radar captured a complete tornado life cycle. One of the greatest successes of the project was documenting the near-ground weather conditions close to tornadoes. Recent improvement in National Weather Service severe weather warnings statistics may be partly due to the application of VORTEX findings.
2000’s: refining the techniques
STEPS – Severe Thunderstorm Electrification and Precipitation Study (2000) In another project, scientists canvassed the Central Plains to collect comprehensive data on low-precipitation supercell thunderstorms. One of their goals was to investigate how polarimetric radars can be used to estimate the type and amount of precipitation in storms. Because of early research like this – later verified through the Joint Polarization Experiment (JPOLE) – the National Weather Service plans to upgrade the WSR-88D radar network with polarimetric capability in 2010. STEPS scientists also discovered some storms had negative, or inverted, cloud-to-ground lightning flashes. Follow-up research might answer a key question of whether or not there is a correlation between lightning polarity and thunderstorm severity.
IHOP – International H2O Project (2002) Scientists from the US, France, Germany, the Netherlands and Canada took part in a weather field project in the Southern Great Plains designed to obtain more accurate and reliable measurements of moisture in the air. IHOP scientists expect the data will help determine the best combination of humidity-measuring instruments to better model rainfall amounts and to improve forecasts of the timing and location of new storms. Better estimates of rainfall amounts will improve flood and flash flood warnings.
VORTEX2 – Verification of the Origins of Rotation in Tornadoes EXperiment2 (2009-10) The largest-ever field program to study tornadoes, VORTEX2 will focus on gaining new insight about how, when, and why tornadoes form, why some thunderstorms produce tornadoes and others do not, the structure of tornadoes, and the relationship of tornadic winds to damage. This field campaign brings together collaborators from 16 different organizations who will operate a fleet of approximately 40 vehicles in a mobile observation network targeting storms in the central Great Plains.
Worldwide expertise
Because NSSL researchers are experts in atmospheric field research, they have had opportunities to participate in multi-national field projects to study cyclones, precipitation and winds from the North Atlantic to the South Pacific, Ireland, the Alps, South America, Spain and Taiwan.
NSSL field projects since 1972
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