Thursday, 15 January 2004: 11:15 AM
VHF lightning detection from GPS orbit as a means of nowcasting global convection and severe weather
Room 6B
David M. Suszcynsky, LANL, Los Alamos, NM; and M. J. Heavner, A. R. Jacobson, M. B. Pongratz, and C. T. Rhodes
Over the last few decades, there has been a growing interest to develop and deploy an automated and continuously operating satellite-based global lightning monitor. Lightning is a ubiquitous feature of most severe weather and is known to be a good indicator of deep convective activity. Lightning flash rates are known to be proportional to the strength of the convective updraft and they can be used as a proxy for locating and nowcasting severe weather. This paper details an ongoing effort to develop a satellite-based Very High Frequency (VHF) Global Lightning And Severe Storm monitor (V-GLASS) based on the detection of VHF emissions from lightning. The proposed system would be an outgrowth of an already-funded constellation of broadband VHF receivers to be flown on the upcoming Block IIF Global Positioning System (GPS) satellite constellation. The use of an existing VHF sensor constellation would greatly reduce system cost and would allow the community to capitalize on the specific benefits of VHF lightning detection, namely the real-time, three-dimensional geolocation of lightning and the potential to identify lightning types (cloud-to-ground vs. intra-cloud) based on VHF power profiles.
The conceptual design for the VGLASS system will be presented and expected system performance and capabilities will be discussed in terms of VHF data analysis results from a similar system currently being flown and operated on the SVN 54 GPS satellite. Analysis of data sets from the SVN 54 VHF receiver, the Los Alamos National Laboratory Sferic Array located in Florida, and GOES-8 infrared imagery will be used to show that a GPS-based VHF lightning monitor will preferentially detect impulsive
(on the order of 10 ms) lightning signatures called narrow bipolar events (NBEs). These lightning signatures are ubiquitous, associated with deep convective processes, and their occurrence rates are excellent statistical indicators of thunderstorm convective strength.
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