Total Lightning Detection Your 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. 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.

AFWA’s Current NLDN Lightning Data Stream Cloud-to-ground (CG) data only But…a large percentage of lightning occurs in cloud (IC) IC often precedes CG by 5-20 min Research shows IC + CG is better indicator of storm severity than CG alone IC + CG is now available at reasonable price

You Don’t Want This to Happen

Three Lightning Detection Technologies VLF reflected between ground 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) 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-VHF LMA – New Mexico Tech (VHF TOA) LDAR-II Vaisala (VHF TOA) – Not on the market LS 8000 Vaisala Interferometry System WTLN WeatherBug (Broadband TOA system) LDAR-II & LMA TOA Systems Small areal coverage Large number of sensors required 3-D displays are good But…Too expensive---few networks exist

VHF Interferometry---a Timing Measurement Technique The 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 for each measurement) The 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 for each measurement) T.O.A.Interferometry dT dd ~100µs~9ns dd dd dd

The Vaisala LS Series Lightning Detection System CG + IC = Total Lightning

LS8000 Sensor – Total Lightning Detection Technology: –VHF Interferometry combined with LF Time of Arrival (TOA) and Magnetic Direction Finding (MDF) –VHF for 2-D cloud lightning mapping –LF 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 Accuracy –Lower overall cost of ownership Technology: –VHF Interferometry combined with LF Time of Arrival (TOA) and Magnetic Direction Finding (MDF) –VHF for 2-D cloud lightning mapping –LF 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 Accuracy –Lower overall cost of ownership

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 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 The LS8000 Sensor

● Interferometry allows longer baselines between sensors (larger areal coverage) and increased accuracy compared to other VHF total lightning systems. ● Proper sensor siting is critical…must have clean horizon. ● Cloud must have active discharges to be detected. ● The LS8000 is not a 3-D system…only 2-D. ● Interferometry allows longer baselines between sensors (larger areal coverage) and increased accuracy compared to other VHF total lightning systems. ● Proper sensor siting is critical…must have clean horizon. ● Cloud must have active discharges to be detected. ● The LS8000 is not a 3-D system…only 2-D. Notes

Examples of Using Total Lightning Data

You See Paths of All Flashes –Detects over 90% of all cloud lightning and CG lightning –Maps the spatial extent of both cloud and the in- cloud portion of CG flashes –Detects over 90% of all cloud lightning and CG lightning –Maps the spatial extent of both cloud and the in- cloud portion of CG flashes

Start End Some Cloud Flashes are Very Long 13 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) 13 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 occurring IC (red) and CG flashes (black) between 0312: :30 UTC 15 June 2001 IC (red) and CG flashes (black) between 0312: :30 UTC 15 June 2001 Fort Worth WSR-88D base reflectivity from 0315 UTC 15 June 2001 High CG Lightning Threat Isolated CG Lightning Threat High CG Lightning Threat IC flashes cover much larger area than CG flashes—the threat area is much larger than where CG occurs.

Imminent CG threat? Can radar alone provide sufficient information to assess lightning data? 24 April 2008 Does the KDFW box have a lightning threat ?

No!! Note VHF total lightning perspective 24 April 2008 IC lightning already occurring

Total lightning perspective 24 April CG flashes on edge of box—far away from main lightning region

Example 2 – Radar Perspective Do both boxes have a lightning threat? UTC 6 November 2006 movie

NLDN CG Lightning Perspective UTC 6 November 2006 CG but no dBZ

VHF Total Lightning Perspective UTC 6 November 2006 movie IC but no dBZ

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

Tucson LS8000 Network IC precedes CG & IC threat persists in CG lull Hail Wind Cloud flash precede CG strokes Cloud flash and CG stroke rates for a severe thunderstorm 11 August 2007

Identification of turbulence within thunderstorm anvils Identification of turbulence within thunderstorm cores Only LS8000 can identify anvil regions Aviation Applications, Turbulence Identification

Building a Total Lightning Network

1 – Vaisala Thunderstorm Sensor 1 – Vaisala Thunderstorm Sensor 3 – Real-time Displays 2 – TLP™ central processor 2 – TLP™ central processor The Lightning Detection Network

Building an LS8000 Network Sites 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) Sites 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 Network Interferometric Network Location Accuracy for a full network of sensors, about 100 km apart. Interferometric Network Location 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 Warnings

The Proposed Northwest Florida Total Lightning Network

VHF Site Projections Cloud Flash DE % 7 sensors at: 1.ABY 2.OZR 3.EVX 4.AQQ 5.VAD 6.CTY 7.TLH 7 sensors at: 1.ABY 2.OZR 3.EVX 4.AQQ 5.VAD 6.CTY 7.TLH > 90% Benning Tyndall Moody Rucker Hurlburt Six military installations receive excellent coverage with this network

CG Flash Detection Efficiency % > 90% in all 6 military areas Hurlburt Rucker Moody Benning Tyndall

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

The Northwest Florida Total Lightning Network The Cost

Collaborations Florida 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 2. WeatherBug TOA System Planned large area (CONUS) Under development Will WeatherBug continue installation?? Many missed discharges

Building a VHF Network Use 2 Sites 100 km apart? Interferometric Network 5 km

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

1 – Vaisala Thunderstorm Sensor 1 – Vaisala Thunderstorm Sensor 3 – Real-time Displays 2 – TLP™ central processor 2 – TLP™ central processor LS-8000 Detection Network

Effect of Close Obstacles Close obstacles are responsible of: dθdθ Masking the sources Changing the apparent azimuth of the source Increasing the Time of Arrival Time-of-Arrival: Inaccuracy in the order of magnitude of the distance to the obstacle: close obstacles can be neglected Interferometry:Inaccuracy of a couple of degrees is common leading to huge errors at long range: close obstacles are extremely critical

Query Data