Thunderstorm Electrification and Lightning Experiment

by Don MacGorman

Day and night during the month of May, a crew of 14 scientists and students scrambled to get in position beneath storms to launch instrumented balloons. The balloons were part of TELEX, the Thunderstorm Electrification and Lightning EXperiment. TELEX 2003 is the first of two sequential spring field programs. The broad objective of TELEX is to learn how lightning and other electrical storm properties are dependent on storm structure, updrafts, and precipitation. This information will point to new ways for the National Weather Service to use lightning observations to improve forecasts and warnings of hazardous weather.

TELEX plans incorporated new sensors now used routinely by NSSL: the Norman KOUN radar, a WSR-88D radar modified with polarimetric parameters to provide information about the particle size and water phase of precipitation, and the Oklahoma Lightning Mapping Array (OK-LMA). 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.

To these two systems, the TELEX team added balloon soundings to measure the electric field profile of storms. An electric field profile can provide scientists information about how a storm becomes electrified and about the forces responsible for lightning. This effort, funded partly by the National Science Foundation (NSF grant ATM-0233268), was the maiden field program for NSSL's newest mobile laboratory used to collect the balloon data. The electric field sensor was custom-built by NSSL with assistance from OU, New Mexico Institute of Mining and Technology, and the National Center for Atmospheric Research (NCAR). Temperature, pressure, and humidity were measured by an NCAR system that also provided GPS tracking of the balloon.

The TELEX team succeeded in flying 14 balloons into nine storms on seven missions. Two of the storms were mesoscale convective systems, a specific TELEX target. NSSL scientists are now analyzing the processed data to address the project's objectives.