Operational: Oklahoma Lightning Mapping Array

On July 31, little more than a year after the original Oklahoma Lightning Mapping Array (OK-LMA) was destroyed in NSSL's "Balloon Barn" fire, the replacement was delivered by New Mexico Institute of Mining and Technology (NMIMT). The system was purchased by grants to scientists at the University of Oklahoma and NSSL who will investigate how lightning characteristics relate to updrafts, precipitation, and severe storm processes. Scientists will also investigate assimilating lightning data into weather forecast models.

The OK-LMA consists of a central analyzer in Norman and ten stations distributed across central Oklahoma. Each station measures the time (to within less than a millionth of a second) at which a VHF radio pulse arrives from the lightning channel segment that generated it. From the differences in times that the pulse arrives at seven or more stations, the system determines the time and three-dimensional location at which the lightning segment itself was formed. Up to thousands of segments can be located for each lightning flash to reveal its initiation and development inside storms. The system maps three-dimensional lightning structure to a range of 75km and the plan location of lightning to a range of 200km.

The day after the system arrived, scientists and technicians from NSSL, OU, and NMIMT began installing the stations at sites that had been prepared in central Oklahoma. All ten stations were installed by the end of September. By late October, the system began trial operation to record lightning data. Just before Christmas, storms finally occurred within range, and the OK-LMA successfully mapped lightning. Minor adjustments continue to be made, with full operation planned to begin this winter, in plenty of time for the spring storm season.

by Don MacGorman