Lightning Detection System
The Kwajalein region has an average annual lightning density of 0.10 flashes km-2 year-1. To put this in context, it is significantly lower than most of the eastern and mid-western U.S.A., while more comparable to the lightning environment through much of the Pacific western U.S.A. at lower elevations. However, lightning can still pose a serious threat to the Range, particularly during the wet season, so that lightning prediction and detection are essential to reduce risk to operations and keep residents safe. Lightning “now-casting” to identify showers which have the potential to produce lightning or are currently producing lightning is done by applying sophisticated algorithms to KPOL radar observations to immediately tag threats. Additionally, a lightning detection system is also deployed through the atoll to detect and locate lightning discharges.
The Kwajalein Lightning Detection System consists of a local data processor and four sensors situated on the islands of Kwajalein, Meck, Illeginni, and Gagan. Developed by Vaisala, the LS7001 sensor detects cloud-to-cloud and cloud-to-ground (CG) lightning. The Total Lightning Processor 2005 (TLP2005) analyzes data gathered by the sensors and is housed in the weather station.
The LS7001 sensors combine direction finding and time-of-arrival to determine the location of lightning strikes. In this approach, direction finding provides azimuth range information, and absolute arrival time provides range information. These data are employed simultaneously in a generalization of the method of circular intersections to obtain optimal estimates of the CG discharge location, employing all available data. This approach does not suffer from the problems inherent with each of the methods when they are used separately. Evaluation of data collected from these sensors indicates the observed location accuracy over most of the atoll is about 5 km.