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NOAA scientists study storms to improve forecasts

by Keli Tarp

Day and night during May and June, a crew of fourteen researchers and students will scramble to get in position beneath storms in central Oklahoma to launch instrumented balloons. Scientists from the NOAA National Severe Storms Laboratory (NSSL) have joined researchers from the University of Oklahoma to study thunderstorms and lightning, with the ultimate goal of using lightning observations to improve forecasts and warnings of hazardous weather.

"We want to relate the electrical structure of storms to production of lightning - especially positive ground flashes - and their relationship to severe weather."

Students help scientists launch an instrumented balloon into a morning mesoscale convective system during TELEX 2003. The yellow tube is the launch tube containing the balloon, and crew members on the right are holding instruments in the balloon train.

The Thunderstorm Electrification and Lightning Experiment (TELEX) field program began Sunday, May 9, and will continue through June 20. Each day, researchers based out of the NSSL facilities in Norman, Okla., will target their armada of intercept vehicles toward a storm with severe potential. By combining and coordinating their resources, scientists will gather data on the storms using a variety of sensors, including weather balloons, Doppler weather radar with polarimetric technology, mobile Doppler radars, and a lightning mapping network.

The broad objective of TELEX is to learn how lightning and other electrical storm properties are dependent on storm structure, updrafts and precipitation. This year is the second of two sequential spring field programs.

“We want to relate the electrical structure of storms to production of lightning – especially positive ground flashes – and their relationship to severe weather,” said Don MacGorman, lighting and storm electricity researcher from the National Severe Storms Laboratory in Norman, Okla. He is leading the team with Dave Rust, chief of the Forecast Research and Development Division at NSSL, and Terry Schuur, research meteorologist with the Cooperative Institute for Mesoscale Meteorological Studies at the University of Oklahoma working at NSSL.

Balloon flight following the launch. The instrument train consists of a parachute, a GPS radiosonde, and an electric field meter for determining the electrical structure of storms.

To determine the electrical structure, TELEX researchers will intercept thunderstorms and launch weather balloons with electric field meters and radiosondes attached. These instruments will record data from inside the storm, including temperature, pressure, humidity, wind speed and direction and the total electric field as well as the balloon’s location. All of this data are collected in NSSL’s mobile laboratory. This electric field profile can provide scientists with information about how a storm becomes electrified and about the forces responsible for lightning.

In addition, TELEX is taking advantage of new sensors now used routinely by NSSL. One is the KOUN radar in Norman, a NEXRAD Doppler weather radar modified with polarimetric technology to provide more information about the types of cloud and precipitation particles.

“We are collecting information on the microphysical structure of storms to help us better understand how storms become electrified,” Schuur said. “This information has been lacking in most previous studies.”

The other new sensor is the Oklahoma Lightning Mapping Array. The OK-LMA is a network of ten stations in central Oklahoma that continuously maps the structure of all types of lightning in three-dimensions out to a range of 75 km and in two-dimensions out to a range of 200 km.

University of Oklahoma researcher Mike Biggerstaff is leading a team using two five-cm mobile radars to gather additional data near storms. The Shared Mobile Atmospheric Research and Teaching Radars (SMART-Radars) provide a view of the winds in the thunderstorms.

In 2003, the TELEX team succeeded in flying fourteen balloons into nine storms on seven missions. Two of the storms were mesoscale convective systems, a specific target of TELEX. NSSL scientists spent the fall and winter analyzing the processed data to address the project's objectives.

TELEX is funded partly by the National Science Foundation.

The National Severe Storms Laboratory in Norman, Oklahoma conducts research to improve accurate and timely forecasts and warnings of hazardous weather events such as blizzards, ice storms, flash floods, tornadoes, and lightning.

[5/17/04]

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