The 8th Conference on Aviation, Range, and Aerospace Meteorology

P8.9
SPATIAL DISTRIBUTION OF CLOUD TO SURFACE LIGHTNING IN AND AROUND THE KWAJALEIN ATOLL

Gail McGovern, Aeromet, Inc, Tulsa, OK; and S. J. Carpenter

In 1996, a series of Model 141 Advanced Lightning Direction Finder (ALDF) sensors became operational in the Kwajalein Atoll. The sensors, located at Kwajalein, Illeginni, Meck, and Gagan, are classified as low gain sensors that detect cloud-to-surface lightning strokes that occur in and around the atoll. The sensors operate with an accuracy of approximately 0.5 - 4 km depending on location in the atoll. The lightning detectors, along with the Model 280 Advanced Position Analyzer (APA) measure the azimuth between the sensor and the lightning stroke. The intersection of the azimuths that each magnetic direction finder measures determines the stroke location. The system reports the date and time of the stroke, as well as the latitude and longitude coordinates of the stroke's location. Using the information reported by the sensors, the frequency with which lightning occurs at specific locations in the atoll, as well as the number of occurrences on specific days, can be determined.

The study of lightning surrounding the atoll is important when considering the nature of operations at the Kwajalein Missile Range. The study, as well as the nature of the storms in which lightning is most likely to occur, is important to the safety of everyone on the atoll, from civilians to those most involved with mission planning. This study will enable range operators on the atoll to have access to valuable information such as when and where lightning most frequently occurs, so that missions on the atoll can be executed under safe conditions.

With the information available, much has been learned about the nature of cloud-to-surface lightning in the tropical environment of the Kwajalein Atoll. Calculations have been made to determine the distances between stroke locations and specific locations in the atoll. A histogram analysis was performed in order to depict the number of lightning strikes that occurred within certain range bins that radiate out from specific important locations in the atoll. This information is vital to the range due to the widespread distribution of equipment necessary to operations. Another set of calculations was performed to determine the number of days with lightning events that occur near specific locations for each month in 1996 and 1997. This information is depicted as a chart, which compares the data for the two years. With the data displayed in this manner, it is possible to determine if any correlation between the two years exists. It is evident from the study, however, that there is not yet enough information to have a clear understanding of the nature of lightning in and around the atoll. This realization only seems to make the lightning detection system so much more vital to the operations. Simply the fact that the lightning occurring at the atoll is not yet fully understood leads to the conclusion that the information produced by the lightning detection system in the future will become increasingly valuable to the overall understanding of cloud-to-surface lightning occurrences in and around the Kwajalein Atoll

The 8th Conference on Aviation, Range, and Aerospace Meteorology