This technique assists in the preparation of lightning forecasts for aviation, power companies, and sporting-event applications.
Research has revealed distinct spatial and temporal distributions of lightning occurrence that are strongly influenced by large-scale atmospheric flow regimes. It was believed there were two flow systems, but it has been discovered that actually there are seven distinct flow regimes.
The Applied Meteorology Unit (AMU) has recalculated the lightning climatologies for the Shuttle Landing Facility (SLF), and the eight airfields in the National Weather Service in Melbourne (NWS MLB) County Warning Area (CWA) using individual lightning strike data to improve the accuracy of the climatologies. A 19-year record of cloud-to-ground (CG) lightning strikes was assembled and manipulated into a usable database of lightning information based on day and time of occurrence, distance from the airfield, and wind flow regime. The software determines the location of each CG lightning strike with 5-, 10-, 20-, and 30-nmi (≈9.3-, 18.5-, 37-, 55.6-km) radii from each airfield. Each CG lightning strike is binned at 1-, 3-, and 6-hour intervals at each specified radius. The software merges the CG lightning strike time intervals and distance with each wind flow regime and creates probability statistics for each time interval, radii, and flow regime, and stratifies them by month and warm season.
The AMU also updated the graphical user interface (GUI) with the new data. As in the previous phase, the AMU stratified the climatologies for each location by time interval, distance, and flow regime. New for this phase, the AMU included all data regardless of flow regime as one of the stratifications, added monthly stratifications, used modified flow regimes, and added three years of data to the period of record.
The AMU used individual strike data from the National Lightning Detection Network (NLDN) instead of NLDN-gridded lightning data to create more accurate climatological values for each range ring than was possible with the gridded data set. Individual strike data is more advantageous than gridded strike data because it simplifies the data processing, it provides more accurate climatologies, and it does not require estimating circular range rings from square grids.
In addition, to better meet customer requirements, the AMU made changes such that the 5- and 10-nmi (≈9.3- and 18.5-km) radius range rings are consistent with the aviation forecast requirements at NWS MLB, while the 20- and 30-nmi (≈37- and 55.6-km) radius range rings at the SLF assist Spaceflight Metrology Group (SMG) in making forecasts for weather Flight Rule violations of lightning occurrence during a shuttle landing.
This work was done by William Bauman and Winifred Crawford of ENSCO, Inc. for Kennedy Space Center. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Software category. KSC-13374