89th American Meteorological Society Annual Meeting

Tuesday, 13 January 2009: 12:00 AM
VHF-VLF dual band lightning mapping array for hurricane intensification study
Room 131A (Phoenix Convention Center)
Xuan-Min Shao, LANL, Los Alamos, NM; and N. W. O'Conno, J. D. Harlin, T. D. Hamlin, and C. A. Jeffery
Earlier observation of lightning activity in hurricanes Katrina and Rita by the Los Alamos Sferic Array (LASA) indicated that eye-wall lighting rate was positively related to the intensification of the hurricanes, as reported by the LASA team three weeks after the landfall of Rita (Shao et al., 2005, Katrina and Rita were lit up with lightning, Eos, Trans Amer. Geophys. Union, 86, 398). LASA works in VLF/LF over frequencies 160 Hz 500 kHz and indiscriminatingly detects either could-to-ground (CG) or intracloud (IC) discharges. In addition, it stores all triggered time waveforms for detailed scientific analysis. For instance, with the waveforms the lightning height can be determined for some IC processes at distances up to 1500 km, by using the time-delayed reflections off the ionosphere.

Nevertheless, to further understand the dynamic relation between the eye-wall lightning and the hurricane intensification, a more detailed insight on the lightning process and an improved hurricane model that can simultaneously exploits the lightning observations are needed. In the summer of 2008, we deployed an 8-station, dual-band lightning mapping array on the shore south of New Orleans. The new sensor is consisted of a VHF (60/5 MHz) power detection channel, similar to the New Mexico Tech's LMA system, and at the same time the original VLF/LF sferic channel. The simultaneous dual band observations will provide us unprecedented physics for lightning discharge processes. The VHF band will provide us detailed 3-d channel structure that depicts the progress of small-scale breakdown processes, while the VLF/LF band provide the large-scale current transportation associated with each of the processes. The combination of the two measurements will provide us the charge amount neutralized by each process, a preferred parameter for the hurricane simulation which will fuse the storm's electrification process into the convective hydrodynamic process. In this report, we will present the initial performance and the preliminary results of the new dual-band lightning array.

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