HR: 10:40h
AN: AE31B-02 INVITED     [PDF]
TI: Improving Regional and National Weather Operations with New Lightning Mapping Technologies
AU: * MacGorman, D R
EM: don.macgorman@noaa.gov
AF: NOAA/National Severe Storms Laboratory, 1313 Halley Cir., Norman, OK 73069 United States
AB: Technology now provides several options for mapping lightning over large regions. The present U.S. National Lightning Detection Network (NLDN) maps lightning ground strike points over continental distance scales, including substantial distances over oceans, and its capabilities are being expanded to map some cloud flashes. VHF time-of-arrival or interferometer networks map all lightning in considerable detail to a range of roughly two few hundred kilometers and are capable of countrywide coverage. VLF networks have demonstrated ability to map lightning globally, including over all oceans. And the demonstrated capability of satellite lightning mappers also could provide global coverage. A major application of these systems at present is thunderstorm detection to help mitigate effects of the lightning hazard itself and of other storm hazards. Thunderstorm detection is particularly valuable in the large regions where radar coverage is poor and not feasible, such as over oceanic and mountainous regions and in impoverished or sparsely populated countries. Though some mapping technologies, such as VLF systems and the present NLDN, are capable of detecting only one or a few points per flash and have a strong bias toward cloud-to-ground flashes, all mapping systems detect thunderstorms adequately for many purposes, including simple data assimilation into numerical weather forecast models. However, storms can be delineated much more quickly, reliably, and clearly by technologies that map all types of lightning and map several pixels or many points per flash. Such mapping systems reveal storm structure comparable in many ways to the structure provided by conventional radars. Depending on the storm and on the technology used, it is possible to map storm features such as overshooting storm tops, rising concentrations of lightning activity apparently reflecting rising updrafts, v-structures at storm top caused by flow around the obstacle presented by strong storm updrafts, sparse-lightning holes in the updraft cores of supercell storms, cores of large lightning density resembling the reflectivity cores of cells, and the maturation of the stratiform precipitation region of mesoscale convective systems, which produce much of the rainfall and flooding in the central United States. However, it is relatively difficult for weather forecasters to incorporate much information from lightning data into their forecasts when using only raw, real-time lightning locations. More research is needed to help extract or summarize information from the lightning data and present it in a form easier for forecasters to digest. Another area in which lightning data can contribute is data assimilation into numerical weather models to improve their forecasts. Research has demonstrated that lightning data can be assimilated into forecast models in much the same way as radar data are, but lightning data could readily be available over large regions of the globe where obtaining radar data is not feasible. Besides improving the initialization of the model by improving the location and extent of storms when the model begins its forecast cycle, a process that itself still can be improved, lightning data could be used in variational schemes to diagnose and compensate for errors often present in the atmosphere at the beginning of a model's forecast cycle. Otherwise, these errors in the model atmosphere often cause the forecast to return close to the state it would have had in 6-12 h without even simple data assimilation.
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
DE: 3337 Numerical modeling and data assimilation
DE: 3360 Remote sensing
DE: 3394 Instruments and techniques
SC: Atmospheric and Space Electricity [AE]
MN: 2003 Fall Meeting