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Lightning Mapping Technology & NWS Warning Decision Making Don MacGorman, NOAA/NSSL.

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Presentation on theme: "Lightning Mapping Technology & NWS Warning Decision Making Don MacGorman, NOAA/NSSL."— Presentation transcript:

1 Lightning Mapping Technology & NWS Warning Decision Making Don MacGorman, NOAA/NSSL

2 Available or Feasible Technologies VLF-to-MF National Networks (mostly CG mapping) – Vaisala’s National Lightning Detection Network – WDT’s United States Precision Lightning Network VHF Mapping Systems (best accuracy & detection eff.) – Vaisala’s Safir Interferometer and LDAR TOA – New Mexico Tech’s Lightning Mapping Array Long-range VLF Networks – PACNET and British Meteorological Office Optical Satellite Mapper (future, NASA/MSFC) – Large detection efficiency VHF Satellite Mapper (future, DOD & Los Alamos) – Much smaller detection efficiency

3 Mapping Oceanic Lightning Lightning mapping: only technically feasible means for global detection of thunderstorms

4 Longitude Latitude -70 70 180 900-90 Global Flash Rate Density: LIS and OTD Courtesy of Hugh Christian, NASA/MSFC km -2 yr -1

5 Noninductive Charging Mechanism Need Riming graupel Liquid water Ice crystals

6 Thunderstorm Charge & Lightning Adapted from Stolzenburg et al., 1998: J. Geophys. Res., 103, 14097-14108. Lightning Initiation Electric force on air becomes too great & causes… Bidirectional development - - + +

7 Thunderstorm Charge & Lightning Bilevel Lightning Flash Cloud-to-ground lightning flash: requires something more, a lower charge

8 Some Relationships in Model & Observations From Ziegler et al. (2003) Graupel mass Lightning Lightning rates proportional to graupel mass, to graupel volume, to cloud ice, and to updraft mass flux through –10 E C level

9 Oklahoma Lightning Mapping Array

10 Comparison of CG versus All Lightning 21 June 2000 15-min accumulations ending at 0015 UTC & 0300 UTC 10 km X 10 km grid Ground Strike Points OnlyAll Lightning

11 Convective Region Flash TELEX Mesoscale Convective System 19 June 2004

12 CG TIME LAG FOR DFW STORMS 10% had no CG flashes 14% had CG within 1 min 50% had CG within 8 min 74% had CG within 23 min

13 CG TIME LAG FOR HIGH PLAINS STORMS 20% had no CG flashes within 60 min 0% had CG within 1 min 50% had CG within 31 min 75% had CG within 44 min

14 Cloud Flash to Ground Flash Ratio from Boccippio et al. (2001) %

15 Initial Applications of CG Mapping Warning of the lightning hazard itself Thunderstorm detection, particularly with poor or absent radar coverage Storm system configuration, growth, and reformation

16 Severe Weather and Lightning Williams et al. (1999)

17 Lightning and Graupel Mass Tornadic Storm Oklahoma City 13 June 1998 Data from the NLDN, NMIMT lightning mapping array, and NSSL polarimetric radar

18 Plan Projection of Lightning Density 29-30 June 2000 Kansas Supercell Storm

19 8 May 2003 Tornadic Supercell Lightning density in 5-minute moving interval NORTH (km) -200 200 -200 200 EAST (km) 0 20 0 ALTITUDE (km) 20 ALTITUDE (km)

20 WDDSII: Lightning Mapping & Radar Depictions of Storms Lightning MappingKTLX WSR-88D Vertical Projection 21 April 2004

21 WDSSII Effect of Spatial Averaging

22 WDSSII Effect of Time Averaging 1-min average5-min average15-min average Height

23 Lightning Data Assimilation into Weather Forecast Models Assimilation PeriodForecast Period -12 Hours0+12 Hours Assimilation by Estimating latent heat release Influencing the convective trigger function ― Simply turn convection on or off ― Influence character of convection

24 Assimilation Effects on 3-Hour Rainfall Accumulation at Initiation 0 6 12 18 No Assimilation All Lightning Assimilated No Convection Suppressed All Lightning Assimilated Convection w/o Lightning Suppressed Only CG Strikes Assimilated Convection w/o Lightning Suppressed

25 Assimilation Effects on Rainfall Accumulated for 3-Hours after Initiation 0 6 12 18 Only CG Strikes Assimilated Convection w/o Lightning Suppressed Forecast After No Assimilation Forecast After All Lightning Assimilated Convection w/o Lightning Suppressed

26 Radar Reflectivity Composite 21 July 2000

27 Lightning Forecasts? Extrapolation “Forecast”

28 Photo copyright by Michael James, 2003


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