Total lightning detection systems at spaceflight meteorology group
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Total Lightning Detection Systems at Spaceflight Meteorology Group. Tim Oram Southern Thunder 2009 Workshop 28 July 2009. Overview. SMG Mission Why we need precise lightning data over a large area Definitions Various lightning detection systems in use at SMG

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Presentation Transcript
Total lightning detection systems at spaceflight meteorology group

Total Lightning Detection Systems at Spaceflight Meteorology Group

Tim Oram

Southern Thunder 2009 Workshop

28 July 2009


Overview
Overview Group

  • SMG Mission

    • Why we need precise lightning data over a large area

  • Definitions

  • Various lightning detection systems in use at SMG

  • Comments on utility of Total Lightning Systems


Smg mission
SMG Mission Group

Spaceflight Operations

Local Weather Support

Provide weather support to Johnson Space Center in Houston for protection of life and property

Includes Lightning Advisory (watch) and Lightning Alert (warning)

  • Provide worldwide forecasts of weather impacts to spaceflight operations for all planned and emergency landings

  • Needless to say -- Thunderstorms are significant


Definitions
Definitions Group

  • Lightning flash: A total lightning discharge, which usually is composed of many distinct luminous events that often occur in such rapid succession the human eye cannot resolve them.

  • Cloud-to-ground lightning: Lightning having a channel spanning from a cloud to the earth

  • Cloud flash: is any lightning flash that does not strike ground

  • Stroke: refers to a specific part of a cloud-to-ground lightning flash. A single stroke consists of a downward propagating leader (either a stepped leader or a dart leader) plus an upward propagating return stroke.

  • NLDN Flash Data: One or more strokes grouped together into a lightning flash

  • Total Lightning: Any lightning discharge (either cloud-to-ground or cloud)

From “Lightning Lexicon” developed by Don MacGorman for Joint Action Group for Lightning Detection Systems (JAG/LDS)


European detection systems

UK Met Office Sferics Group

Spanish AEMET CG Flash

Meteofrance CG

Ingested into AWIPS via LDAD

European Detection Systems


Us nldn data
US NLDN Data Group

NLDN CG Flash data in AWIPS

NLDN Total Lightning (including CG stroke) data in MIDDS

Example is NLDN Total Lightning Data


Cg flash vs total and cg stroke
CG Flash vs. Total and CG Stroke Group

CF=Circles

Stroke at JSC?

MIDDS: 21 Strokes and 3 Cloud Flashes (CF)

AWIPS: 10 CG Flashes


Vhf lightning mapping systems

Houston LDAR netCDF Grid Group

KSC – 45th SW 4DLSS

VHF Lightning Mapping Systems

A 12-minute loop of Houston LDAR data as displayed in AWIPS. Each image in loop is ten minutes of LDAR II sources and each image is two minutes apart. Red circle is the JSC warning area (6 mile radius). Data provided by Texas A&M University.

5-minutes of lightning data.

Similar to Operational Display (Operational display is black/white)

Individual sources displayed in real-time as received.


Local detection systems

Field Mill Group

Thorguard

Local Detection Systems

A “field mill” measures the electrostatic field produced by the thunderstorm charges. A field mill can also detect the change in the electrostatic field when lightning destroys that charge.

“THOR GUARD TM effectively reads the activity within the electrostatic field through a proprietary program developed after hundreds of hours of thunderstorm monitoring, and will predict the probability of a lightning strike within a predetermined area of concern. This program can also project the potential for deadly "bolts out of the blue," which are strikes that seem to come from nowhere and cause a high percentage of lightning fatalities. “ (www.thorguard.com)


General comments
General Comments Group

  • Complementary data is important to assess the quality and accuracy of the lightning data

    • Assessing quality of any data (not just lightning) is important for forecast and warning process

    • Multiple sources of lightning information are not redundant

    • Trust but verify (No offense meant to the vendors!)

  • Stroke data versus flash is preferred for CG

    • More complete picture of threat

    • Potentially a better answer to question of “Did lightning hit this spot?”

  • Addition of Total Lightning from NLDN is valuable particularly if location is reasonably accurate and you can truly discriminate between CG and cloud lightning (which seems to be the case)


Comments on total lightning
Comments on Total Lightning Group

  • Total lightning mapping systems (LDAR/LMA) have best depiction of threat compared to stroke/flash data

  • Prefer individual sources to grid product for understanding lightning structure. Also, the data are more timely.

  • netCDF grids are best way to integrate total lightning into AWIPS for now. However, grids lose some of the advantage of total lightning mapping as a precursor to cloud-to-ground. Takes time to grid and disseminate the data. Important issue when issuing local warnings.

  • Can be the difference between issuing a local watch and warning or holding off

  • A local system for detecting lightning in real-time (LDAR, LMA, Thorguard) provides a few minutes advantage for disseminating warning information – can be significant to safety



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