Lightning detection over Houston, Texas is possible with the Lightning Detection
and Ranging (LDAR-II) network and the National Lightning Detection Network
(NLDN). A comparison of the two datasets in conjunction with 37 isolated, ordinary
thunderstorms reveals a time separation of 3.1 minutes between the first detected Very
High Frequency (VHF) source (i.e. first intracloud discharge) and the first cloud-toground
(CG) lightning flash. This CG warning time is increased to 16.1 minutes when
using the radar-defined criterion of when the 30-dBZ contour first reaches the -10°C
isotherm level.
Several attempts were made to establish a similar characteristic that could be
used to forewarn the occurrence of the final CG in this storm type. Based on the average
radar characteristics during the last CG flash in each thunderstorm case, CG activity
comes to an end when the 45-dBZ echo falls below the -10°C isotherm.
Detection efficiencies that remain slightly less than perfect for each network may
have allowed for some error when analyzing VHF sources and ground flashes for each convective case. Exhibiting this possible error, four cases actually recorded a greater
number of CG flashes than intracloud flashes, which is contrary to typical lightning
characteristics.
Future studies hope to increase the number of thunderstorm cases to analyze as
the LDAR network continues to observe more lightning events. Also, similar approaches
could be implemented in differing geographic regions of the country to observe if these
lightning characteristics vary depending on latitude, longitude, or climate.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2421 |
| Date | 15 May 2009 |
| Creators | Clements, Nathan Chase |
| Contributors | Orville, Richard E |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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