Total Lightning DetectionYour Name& Affiliation

Why Use Lightning Information?Lightning data is real-time, no delays!

Lightning assists in routing aircraft around storms.

It is absolutely necessary for safety during ground operations--refueling and other aircraft preparations.

Lightning is a valuable meteorological data source that enhances other sources such as weather radar.

Lightning information covers a large area, even extending out to the ocean.

Lightning information is very economical.

AFWAs Current NLDN Lightning Data StreamCloud-to-ground (CG) data onlyButa large percentage of lightning occurs in cloud (IC)IC often precedes CG by 5-20 minResearch shows IC + CG is better indicator of storm severity than CG aloneIC + CG is now available at reasonable price

You Dont Want This to Happen

Three Lightning Detection TechnologiesVLF reflected betweenground and ionosphere(long-range network)LF/VLF ground wave(NLDN)VHF line-of-sight only(SAFIR, LDAR II, LS8000)

CG Lightning Detection--LF C-G lightning typically detected in the LF range.Longer detection range.Ability to locate ground strike point with high accuracy.Ability to determine lightning polarity and peak current.Some ability to differentiate between C-G and cloud lightning.C-G lightning has a fingerprint detected in its waveform.C-G lightning is located using one of these methods. Time of Arrival (TOA) Magnetic Direction Finding (MDF)

Total Lightning (IC+CG) Detection-VHFLMA New Mexico Tech (VHF TOA)LDAR-II Vaisala (VHF TOA) Not on the marketLS 8000 Vaisala Interferometry SystemWTLN WeatherBug (Broadband TOA system)LDAR-II & LMA TOA Systems Small areal coverage Large number of sensors required 3-D displays are good ButToo expensive---few networks exist

VHF Interferometry---a Timing Measurement TechniqueThe two most common methods of locating lightning in the VHF range are Time-of-Arrival and Interferometry. Interferometry consists of measuring the time difference between closely spaced antennas. The main difference with Time-of-Arrival is that it operates on continuous waves and not individual pulses.The accuracy is achieved by integrating a very large number of periods (typically 11 000 for each measurement)

The Vaisala LS Series Lightning Detection System

CG + IC = Total Lightning

LS8000 Sensor Total Lightning DetectionTechnology: VHF Interferometry combined with LF Time of Arrival (TOA) and Magnetic Direction Finding (MDF)VHF for 2-D cloud lightning mappingLF for accurate CG detection (as in NLDN)Benefits:Longer baseline network (fewer sensors) to cover same area as VHF-TOA (LDAR II)Accurate LF CG data, improvements to 250 meter Location AccuracyLower overall cost of ownership

The LS8000 Sensor The 5 dipole antenna VHF interferometry system locates cloud discharges with a high level of accuracy

The LF antenna from the gives detailed CG information

Combining the two gives a clear picture of total lightning and mapping the full spatial extent of flashes

Notes

Interferometry allows longer baselines between sensors (larger areal coverage) and increased accuracy compared to other VHF total lightning systems.

Proper sensor siting is criticalmust have clean horizon.

Cloud must have active discharges to be detected.

The LS8000 is not a 3-D systemonly 2-D.

Examples of Using Total Lightning Data

You See Paths of All FlashesDetects over 90% of all cloud lightning and CG lightning

Maps the spatial extent of both cloud and the in-cloud portion of CG flashes

Some Cloud Flashes are Very Long13 October 2001 North Texas

Cloud flash was ~190 km long (from ~ Waco to Dallas, TX).

It put down two CG flashes along the way (white symbols)

Quiz--Where is Lightning Threat?Not just where CG is occurringIC (red) and CG flashes (black) between 0312:30 - 0317:30 UTC 15 June 2001Fort Worth WSR-88D base reflectivity from 0315 UTC 15 June 2001High CG Lightning ThreatHigh CG Lightning ThreatIC flashes cover much larger area than CG flashesthe threat area is much larger than where CG occurs.

ImminentCG threat?Can radar alone provide sufficient information to assess lightning data?

24 April 2008Does the KDFW boxhave a lightningthreat ?

No!! Note VHF total lightning perspective

24 April 2008IC lightning already occurring

Total lightning perspective

24 April 20083 CG flashes on edge of boxfar away from mainlightning region

Example 2 Radar PerspectiveDo both boxes have a lightning threat?07 - 08 UTC 6 November 2006 movie

NLDN CG Lightning Perspective

07 - 08 UTC 6 November 2006CG but no dBZ

VHF Total Lightning Perspective

07 - 08 UTC 6 November 2006 movieIC but no dBZ

Example 3Go to animation! Tucson Total Lightning NetworkJuly 26, 2008

Tucson LS8000 NetworkIC precedes CG & IC threat persists in CG lullHailWindCloud flash precede CG strokesCloud flash and CG stroke rates for a severe thunderstorm 11 August 2007

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Aviation Applications, Turbulence IdentificationIdentification of turbulence within thunderstorm anvilsIdentification of turbulence within thunderstorm coresOnly LS8000 can identify anvil regions

Building a Total Lightning Network

The Lightning Detection Network 1 Vaisala Thunderstorm Sensor3 Real-time Displays2 TLPcentral processor

Building an LS8000 NetworkSites must be carefully selected:

Distance between sensors: 100 to 150 km for an Interferometric network

Sensors should be in Triangle strips

Each sensor should have an optimal Field of View---No far obstacles

Antenna surroundings should be as clean as possible---No close obstacles

Sites should be free of strong radio sources

Noise floor should be as low as possible

Power and communication should be easily available

Site should be accessible (installation and maintenance)

Building a VHF NetworkInterferometric NetworkLocation Accuracy for a full network of sensors, about 100 km apart.

Location accuracy is better than 1 km almost everywhere

What Displays Would You Have ?

Total Lightning Display Flash Extent Density (FED)

Total Lightning Display CLD FED map with CG overlay

Total Lightning Display CLD flash map with CG overlay

Have Multiple Windows

Nowcast Storm Movement

Visual, Audible, and E-mail Warnings

The Proposed Northwest Florida Total Lightning Network

VHF Site Projections Cloud Flash DE %7 sensors at:ABYOZREVXAQQVADCTYTLH

> 90%BenningTyndallMoodyRuckerHurlburtSix military installations receive excellentcoverage with this network

CG Flash Detection Efficiency % > 90% inall 6 military areasHurlburtRuckerMoodyBenningTyndall

CG Stroke Location Accuracy (km)< 0.5 km over land

The Northwest Florida Total Lightning NetworkThe Cost

CollaborationsFlorida State University has been researching the operational use of lightning data for many years.They would like to receive the data and work with us to use the data to maximum advantage.This would involve visits, seminars, etc. to DOD facilities.

Questions

Reserve slides you probably cannot use follow

2. WeatherBug TOA System

Planned large area (CONUS) Under development Will WeatherBug continue installation?? Many missed discharges

Building a VHF NetworkUse 2 Sites 100 km apart?Interferometric Network

5 km

Building a VHF NetworkInterferometric Network:Location Accuracy for 3 sensors, about 100 km apart.

Aircraft Interference

Aircraft become electrically charged when flying through ice crystal clouds (cirrus, thunderstorm anvils). Emits steady stream of weak sparks that are easily recognized.

LS-8000 Detection Network 1 Vaisala Thunderstorm Sensor3 Real-time Displays2 TLPcentral processor

Effect of Close ObstaclesClose obstacles are responsible of:dMasking the sourcesChanging the apparent azimuth of the source

Increasing the Time of ArrivalTime-of-Arrival: Inaccuracy in the order of magnitude of the distance to the obstacle: close obstacles can be neglectedInterferometry:Inaccuracy of a couple of degrees is common leading to huge errors at long range: close obstacles are extremely critical

Query Data

Probably want to draw a box around Dallas County and highlight it with animation. Pose the question to audience on whether or not there will be a threat of CG across highlighted county (Dallas County). *FED only. Note high values of FED associated with intense convection and high reflectivity values. (Label county names?)*Note 3 CG flashes in Dallas County --- well northeast of the highest flash densities and highest radar reflectivity regions. *Focus on the highlighted counties during the animation. Denton and Collin Counties are north of DFW. *Highlight the same counties as in the previous two slides.*Highlight same counties as in the previous slide so audiences attention drawn there. *This slide shows a time series of cloud and CG lightning rates for a typical, small thunderstorm. Time is shown on the x-axis and increases from left-to-right and the flash rate (in flashes per 5 minute time intervals) is shown on the y-axis and increases from bottom-to-top. The cloud flash rates were detected with a VHF lightning mapping network that is similar to Vaisalas LS8000 lightning mapping networks and the CG lightning rates were detected using LF CG lightning detection sensors similar to the LS7000 or the similar functionality also existing in the LS8000. There are two topics on this slide that should be explained to customers. The first topic relates to the earlier detection of a thunderstorm using LS8000 VHF lightning mapping data. Notice in the time series that the cloud flashes start at 19:45 UTC and the CG flashes start at 19:55 UTC. This is a rather typical 10 minute lead time between the first cloud flash produced by a thunderstorm and the first CG flash produced by a thunderstorm. The second topic relates to the sensitivity of cloud lightning detection from a LS8000 network to thunderstorm growth and dissipation. Notice that the cloud lightning flash rates increase much more rapidly than the CG lightning flash rates during the first 10 minutes of the storm. This rapid increase in cloud flash rates shows the growth phase of the thunderstorm. Also, notice that the CG lightning flash rates peak much later in the thunderstorms lifetime (near 20:15 20:25 UTC) and these CG lightning flash rates are also peaking at the time the thunderstorm is actually dissipating. Notice how the cloud flash rates are steadily decreasing after 20:20 UTC. The take home messages from this slide are that cloud lightning detection by LS8000 sensors give a customer earlier warning of thunderstorm activity and CG lightning hazards and also are much more sensitive to thunderstorm growth and dissipation than CG lightning detection from LS7000 networks. This slide shows a flash extent density image from several thunderstorms detected by a LS8000 type of VHF total lightning detection network in the Dallas-Fort Worth area of Texas. The shades of red and white show the main thunderstorm cores or highest lightning producing areas of the storms. This is important for identification of the most turbulent areas of thunderstorms. The lightning activity shown toward the east-northeast of these thunderstorms (shades of purple) show lightning propagating through anvil clouds located out ahead of the thunderstorms. These anvil regions identified by lightning are also important for determining other turbulent areas associated with thunderstorm activity. LS7000 networks could help with identification of the turbulent thunderstorm cores, but not the anvil regions of thunderstorms.Sensors do no locate ltg, the central processor combines sensor information to create a solution.CP broadcasts (transmitir, emitir) information and stores location and raw sensor data.Displays can be provided by Vaisala, or integrate in something Met has.

Sensors do no locate ltg, the central processor combines sensor information to create a solution.CP broadcasts (transmitir, emitir) information and stores location and raw sensor data.Displays can be provided by Vaisala, or integrate in something Met has.