Lightning Detection Systems Used for Americas Space Program in Florida

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Southern Thunder Workshop (28-30
Jul 09)
Unclassified
Lightning Detection SystemsUsed for Americas
Space Programin Florida Mr. William P.
Roeder Meteorologist 45th Weather Squadron
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Overview

• Lightning and Space Launch in Florida
• Four-Dimensional Lightning Surveillance System
  (4DLSS)
• Other 45 WS Lightning Detection Systems not
  Covered

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Lightning and Space Launch in Florida

• Americas Space Program in Florida is at
  Cape Canaveral AFS and NASA Kennedy Space Center
  in Central Florida
• Central Florida is U.S. Lightning Alley
• Space Launch and Processing for Space Launch
  are Highly Sensitive to Lightning
• Lightning Launch Commit Criteria
• Ground Processing
• Warnings for Personnel Safety and Resource
  Protection
• Assessing Induced Current Impacts on
  Payloads and Vehicle Electronics

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Lightning and Space Launch in Florida

• Solution
• One of the Best Suite of Lightning Detectors
  in all of Operational Meteorology
• Four Dimensional Lightning Surveillance
  System (4DLSS)
• Launch Pad Lightning Warning System (LPLWS)
• National Lightning Detection Network (NLDN)
• Radar for Lightning Prediction
• WSR-74C
• WRR being Implemented
• See briefing by McNamara
• Only 4DLSS covered here

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4DLSS

• 4DLSS New System Provides Major Upgrade to
  LDAR, and Integrates Old CGLSS
• LDAR Detects Step Leaders from Intra-Cloud
  Lightning
• CGLSS Detects Return Strokes from
  CG-Lightning
• LDAR-II Upgrade
• 9 LDAR-II Sensors vs. 7 Old Sensors in LDAR
• 2.5x Larger Horizontal Spacing than LDAR
• New CP-8000 Processor
• CGLSS-II Upgrade
• Same 6 IMPACT Sensors used in CGLSS
• Processed in CP-8000
• Implemented April 2008 into Operations

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4DLSS
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4DLSS
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4DLSS
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4DLSS

• Performance Intra-Cloud Lightning
• Detection Rate Same or Better than LDAR
• 100 of Flashes within the Network,
  Including CCAFS/KSC
• All Flashes, but not All Step Leaders
• 40 More Step Leaders than LDAR
• Location Accuracy Same or Better than LDAR
• 100 m within the Network
• Radial Location Error Increases Much Less with
  Distance
• Much Less Radial Smearing than LDAR
• Aircraft Signals Eliminated
• Occasional Light Noise on Cold Mornings

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4DLSS

• 4DLSS Flash Detection Rate () for Lightning
  Aloft
• 100 Inside Network, Including CCAFS/KSC
• Vaisala Modeling Study

75 Km
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4DLSS

• 4DLSS Step-Leader Location Accuracy (Km) for
  IC-Ltg
• 100 m Inside Network, Including CCAFS/KSC
• Vaisala Modeling Study

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4DLSS

• Performance Cloud-to-Ground Lightning
• Detection Rate same as CGLSS
• 98 of Return Strokes within 50 NM of the
  Network
• Location Accuracy same as CGLSS
• 250 m Median / 50 Error
• 50 of Return Strokes will be within 250 m of
  Reported Location
• 50 will be Farther than 250 m
• 600 m 99 Error
• 99 of Return Strokes will be within 600 m of
  Reported Location
• 1 will be Farther than 600 m

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4DLSS

• Performance Cloud-to-Ground Lightning
  (can't.)
• Detects All Return Strokes per Flash
• Old CGLSS Reported Only 1 Stroke per Flash
• Lightning has 3.5 Return Strokes per Flash on
  Average
• ? 50 of Flashes Have Return Strokes with
  Multiple Ground Strike Locations
• Average Separation 3 Km
• Up to 12 Km Separation
• Vital to Main Purpose of CG Component of
  4DLSS, Advising Customers if Inspection of
  Payload/Rocket Electronics for Damage from
  Induced Currents

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4DLSS

• Performance Cloud-to-Ground Lightning
  (can't.)
• Fixed CGLSS Problem of Distant Strokes being
  Reported too Close
• Intentionally done in CGLSS to Increase
  Detection Rate of Local Lightning
• Reduces Reported Detections Compared to CGLSS,
  but is More Representative
• Combining the Two Effects, 4DLSS Reports
  150 More Strokes than CGLSS
• Effect-1 More Strokes from Detecting All
  Strokes
• Effect-2 Fewer Strokes from Fixing Distant
  Lightning Reported too Close

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• Example of Some 4DLSS IC-Ltg Advantages
• Same Date/Time/Sample Volume

LDAR
4DLSS

• Less Radial Smearing
• Reduced Lightning Warnings from
  Thunderstorms just on Mainland Smearing
  Back Over Warning Areas

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Example of Some 4DLSS IC-Ltg Advantages - Same
Date/Time/Sample Volume
LDAR
4DLSS

• Better Detection Rate and Less Radial
  Smearing Combine to Show More Detailed
  Lightning Structures

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CGLSS
Example of Some 4DLSS IC-Ltg Advantages - Same
Date/Time/Sample Area
4DLSS

• Distant Lightning Wrongly Located too Close by
  CGLSS
• Virtually Eliminated by 4DLSS

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4DLSS
Strong Case of Occasional Noise
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4DLSS
Strong Case of Occasional Noise

• Sometimes Occurs During Strong Nocturnal
  Inversions
• Easily Recognized
• Random 3-D Distribution
• Doesnt Look Like Lightning
• Centered on Network
• Meteorological Conditions
• Lightning not Expected
• Likely Due to Ducting and Transmitter at
  4DLSS Frequency
• Transmitter not Necessarily Located in
  Middle of Noise. Noise Location Solutions
  Randomly Distributed Around Center of Network.

• Suggestions?
• Tweak Sensitivity?
• Tweak Noise Filters?
• Adjust Frequency?
• Do Nothing for High Detection Rate?

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4DLSS

• New Flash Algorithm Needed
• Important to Many Researcher Using 4DLSS!
• Previous Location Error Ellipse as a Function
  of Range No Longer Applies
• Radial Error Increases Less with Range vs. Old
  LDAR
• Much Less Radial Smearing than LDAR
• Used to Cluster Detections into Same Flash
• Time Difference Between Events Also Used
• Possible New Algorithm
• Set Radial Error Increase with Range to
  Azimuthally Rate
• Location Errors Circles Growing in Radius
  with Range
• Assumes Radial Smearing Eliminated
• Azimuthally Error Rate with Range Needs Retuning

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4DLSS
Location Error Models
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4DLSS

• Future Possibilities
• Upgrade Old LDAR Display Processor and Monitor
• Many Step Leaders Detected but not Displayed,
  due to Low Throughput of Old LDAR Display
  System, which was not Upgraded Under 4DLSS
  Project
• Status Requirement Statement Submitted
• Long-term Sustainability of LDAR-II and IMPACT
  Sensors has Become Problematic
• Status
• LDAR-II SMC Purchased Spare Parts.
  Analysis of Impact Pending
• CGLSS Possible Replacement with LS7001
  Sensors, Funding Under
  Consideration

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4DLSS

• Future Possibilities (can't.)
• Incorporate Nearby NLDN Sensors in Real-time
• 9 NLDN Sensors in FL, GA, and Bahamas
• Reduce Problem of Local Strong Strokes being
  Missed
• 25 of Return Strokes 50 KA in Network are
  Missed ( 2.5 of All Return Strokes Missed)
• Improve Location Accuracy
• Documented Location Accuracies Assume All
  CGLSS Sensors are used in Solution. That is
  Often not True
• Reduce Highly Eccentric Error Ellipses
• When Few Sensors Used in Solution, Highly
  Eccentric Error Ellipses Can Result
• Can Make it Hard to Tell if a Return Stroke
  Exceeded the Distance/Intensity Thresholds to
  Inspect Payload Vehicle
• Status Feasibility Being Investigation

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4DLSS

• Future Possibilities (can't.)
• Acquire Fault Analysis and Lightning Location
  System (FALLS) from Vaisala, Inc.
• Allow Viewing of Error Ellipse for
  Individual Return Strokes
• Other Capabilities
• Status Purchased, Awaiting Delivery
• Add 1-3 More Sensors (10-12 Total)
• New Site Locations TBD
• Status No Action Taken,
  Subject to Funding
• Eliminate Occasional Noise Problem
• Status No Action Taken

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Summary

• Lightning and Space Launch in Florida
• Four-Dimensional Lightning Surveillance System
  (4DLSS)
• 40 More Step Leaders than LDAR
• 150 More Return Strokes than CGLSS
• All Return Strokes vs. One per Flash in CGLSS
• Implemented Apr 08

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Lightning Detection SystemsUsed for Americas
Space Program in Florida
Questions? william.roeder_at_patrick.af.mil
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Example of Some 4DLSS IC-Ltg Advantages - Same
Date/Time/Sample Volume
LDAR
4DLSS

• Better Detection Rate
• LDAR 900 Detections/Min
• 4DLSS 1,400 Detections/Min
• 4DLSS Reported 47 More Step Leaders than
  LDAR in this Case

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Example of Some 4DLSS IC-Ltg Advantages - Same
Date/Time/Sample Volume
LDAR
4DLSS

• Aircraft Noise Eliminated
• Unexpected Benefit
• Caused by Wider Network and Noise Reduction
  (weak signals from aircraft fall below
  lightning detection thresholds more often
  with wider spaced sensors and so dont meet
  the required number of sensors to be lightning)

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Example of Some 4DLSS IC-Ltg Advantages - Same
Date/Time/Sample Volume
LDAR
4DLSS

• Better Detection Rate
• Cells Missed by LDAR may be due to
  Non-synchronized Update Times, Rather than
  Better Detection Rate

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CGLSS
Example of Some 4DLSS CG-Ltg Advantages - Same
Date/Time/Sample Area
4DLSS

• CGLSS 5,916 Strokes 4DLSS 15,686 Strokes
• 4DLSS Reported 165 More Return Strokes than
  CGLSS in this Case

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