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Relationships between Long-Range Lightning Networks and TRMM/LIS Observations

Relationships between Long-Range Lightning Networks and TRMM/LIS Observations. Scott D. Rudlosky NOAA/NESDIS/STAR College Park, MD Collaborators: R . H. Holzworth , L. D. Carey, C . J. Schultz, M. Bateman, K. L. Cummins, R . J. Blakeslee, S. J. Goodman. Motivation.

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Relationships between Long-Range Lightning Networks and TRMM/LIS Observations

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  1. Relationships between Long-Range Lightning Networks and TRMM/LIS Observations Scott D. Rudlosky NOAA/NESDIS/STAR College Park, MD Collaborators: R. H. Holzworth, L. D. Carey, C. J. Schultz, M. Bateman, K. L. Cummins, R. J. Blakeslee, S. J. Goodman

  2. Motivation • Recent advances in lightning detection technologies have improved our understanding of thunderstorm evolution in the data sparse oceanic regions.

  3. Motivation • Recent advances in lightning detection technologies have improved our understanding of thunderstorm evolution in the data sparse oceanic regions. • Although the expansion and improvement of long-range lightning datasets have increased their applicability, these applications require knowledge of network detection capabilities.

  4. Motivation • Recent advances in lightning detection technologies have improved our understanding of thunderstorm evolution in the data sparse oceanic regions. • Although the expansion and improvement of long-range lightning datasets have increased their applicability, these applications require knowledge of network detection capabilities. • Improved knowledge of relationships between satellite and ground-based lightning datasets will allow researchers, algorithm developers, and operational users to better prepare for the spatial and temporal coverage of the upcoming GOES-R Geostationary Lightning Mapper (GLM).

  5. TRMM Lightning Imaging Sensor (LIS) • Reports the location and timing of events, groups, flashes, and areas • Records both IC and CG flashes, but with limited view time • Detection Efficiency – Night = 93% ± 4% – Noon = 73% ± 11% LIS Flash Density (2009-2011)

  6. World-Wide Lightning Location Network • Observes very low frequency (VLF) radiation (3-30 kHz) emitted by lightning • Earth-Ionosphere waveguide allows for global coverage with only 50-60 sensors • WWLLN DE relative to the NLDN Abarcaet al. (2010) • Jacobson et al. (2005) • Accurate to within 50 µs and 15-20 km WWLLN Sensor Locations

  7. GLD360™ Network Specifications • From Vaisala’s GLD360 Worksheet • Flash detection efficiency • > 70% in most of the Northern hemisphere • 10-50% in the Southern hemisphere • Median location accuracy of 10 km or better • Network uptimes nearing 99% • Data feed uptimes of better than 99%

  8. Comparison Methods Comparison of WWLLN and LIS Flash Densities • Flash density comparison • Requires large sample size • No information on location accuracy (LA) or flash-level LIS characteristics • Flash-by-flash comparison • Match individual LIS flashes with long-range network reported strokes • Spatial criteria • Within 25 km of any LIS group • Temporal criteria • Within 330 ms before, during, and 330 ms after the LIS flash WWLLN LIS Example of Matched LIS/WWLLN Reports

  9. Baseline Analysis (NLDN) • Apply comparison methods originally developed for long-range network analysis • NLDN performance is well documented • Analysis of NLDN-reported flashes (i.e., not strokes) 0.5° × 0.5°

  10. WWLLN Analysis (2009-2011) 2° × 2°

  11. Greatest WWLLN DE Over the Oceans WWLLN Detection Efficiency (2009-2011) Mean -CG Peak Current (NLDN) • Both meteorological and technological contributions • Diurnal effects have a strong influence on both of these categories • Stronger (but less frequent) flashes over the ocean • Signal propagation (e.g., solar influence on earth-ionosphere waveguide) 0.5° × 0.5°

  12. Temporal Evolution of WWLLN DE

  13. WWLLN detects the strongest LIS flashes • Table compares the average characteristics of LIS flashes detected by WWLLN (Matched) with those not detected by WWLLN (Not Matched) • Koshak et al. introduced two flash level characteristics as potential return stroke detectors • mga - maximum group area • mneg - maximum number of events per group groups – Mean number of groups per flash events – Mean number of events per flash delta – Mean duration of LIS flashes (sec) farea – Mean area of LIS flashes (km2) radiance – Mean radiance of LIS flashes

  14. GLD-360 Analysis (Jun. – Nov. 2011) • Important Caveat • Data has been post-processed (i.e., not provided in real-time) 2° × 2°

  15. Summary • WWLLN DE is improving with time • From 6% during 2009 to 8.1% during 2011

  16. Summary • WWLLN DE is improving with time • From 6% during 2009 to 8.1% during 2011 • Long-range networks detect the strongest LIS flashes

  17. Summary • WWLLN DE is improving with time • From 6% during 2009 to 8.1% during 2011 • Long-range networks detect the strongest LIS flashes • Greatest WWLLN DE values observed over the oceans

  18. Summary • WWLLN DE is improving with time • From 6% during 2009 to 8.1% during 2011 • Long-range networks detect the strongest LIS flashes • Greatest WWLLN DE values observed over the oceans • Not as clear of a land/ocean contrast in the GLD-360 DE

  19. Summary • WWLLN DE is improving with time • From 6% during 2009 to 8.1% during 2011 • Long-range networks detect the strongest LIS flashes • Greatest WWLLN DE values observed over the oceans • Not as clear of a land/ocean contrast in the GLD-360 DE • Difficult to separate meteorological and technological influences on spatial and temporal DE variability

  20. Summary • WWLLN DE is improving with time • From 6% during 2009 to 8.1% during 2011 • Long-range networks detect the strongest LIS flashes • Greatest WWLLN DE values observed over the oceans • Not as clear of a land/ocean contrast in the GLD-360 DE • Difficult to separate meteorological and technological influences on spatial and temporal DE variability • Average distance between LIS flashes and WWLLN/GLD-360 strokes is 10-11 km (NLDN = 9.75 km)

  21. Summary • WWLLN DE is improving with time • From 6% during 2009 to 8.1% during 2011 • Long-range networks detect the strongest LIS flashes • Greatest WWLLN DE values observed over the oceans • Not as clear of a land/ocean contrast in the GLD-360 DE • Difficult to separate meteorological and technological influences on spatial and temporal DE variability • Average distance between LIS flashes and WWLLN/GLD-360 strokes is 10-11 km (NLDN = 9.75 km) • Multiple WWLLN/GLD-360 strokes during some LIS “flashes”

  22. Summary • WWLLN DE is improving with time • From 6% during 2009 to 8.1% during 2011 • Long-range networks detect the strongest LIS flashes • Greatest WWLLN DE values observed over the oceans • Not as clear of a land/ocean contrast in the GLD-360 DE • Difficult to separate meteorological and technological influences on spatial and temporal DE variability • Average distance between LIS flashes and WWLLN/GLD-360 strokes is 10-11 km (NLDN = 9.75 km) • Multiple WWLLN/GLD-360 strokes during some LIS “flashes”

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