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Los Alamos Sferic Array

The Los Alamos Sferic Array (LASA) was originally built for ground verification of lightning observations by the FORTE satellite. LASA has evolved into a tool for studying both FORTE and GPS lightning observations, as well as a stand alone tool for studying lightning. LASA is an array of LF/VLF electric field change meters which is digitized at 1 MHz with 12 bit resoltuion. Each LASA station utilizes GPS receivers to provide absolute event time tagging with an accuracy of better than 2 $\mu$s. Using differential time of arrival methods for the event times at multiple stations, lightning events are geo-located. Most commonly, LASA records are 8 ms in duration and have been collected by a threshold triggering mechanism that includes 2 ms of pre-trigger data. Based on initial investigation into intracloud and leader LF/VLF radiation, 80 ms and 1 s records were collected by LASA stations to provide stroke context.

During operations of the sferic array from 1998 through the present, stations have been located in the United States, in the states of New Mexico, Texas, Nebraska, Colorado, and Florida. [Smith et al.(2002)] describe the operation and instrumentation of LASA and characterize the accuracy of LASA geolocation. The classification of NBEs is also describe in detail. Briefly, the NBEs are distinct based on the relative lack of neighboring radiation (or the isolation) and the narrow nature of the signature (the rise time and the fall time of the waveform). The classification of CG events is based solely on the relatively slow (greater than 30 $\mu$s) fall time.


next up previous
Next: Data Up: Introduction Previous: Lightning LF/VLF Radio Emissions
Matt Heavner 2003-04-02