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#612202 - 07/06/2001 19:11 How does the lightning tracker work.
AussieJimbo Offline
Junior Member

Registered: 07/06/2001
Posts: 129
Loc: Canberra
I'm curious, can someone tell me how the tracker detects where lightning strikes occur.


Sorry if this is a newbie YART. I searched the forum but didn't find an answer.

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#612203 - 07/06/2001 19:29 Re: How does the lightning tracker work.
gustfront Offline
Thundergod

Registered: 19/05/2001
Posts: 3393
Loc: North Balgowlah, Sydney, 33.79...

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#612204 - 07/06/2001 19:40 Re: How does the lightning tracker work.
AussieJimbo Offline
Junior Member

Registered: 07/06/2001
Posts: 129
Loc: Canberra
Thanks GF, that's useful information but I'm interested in the underlying mechanism that makes it possible.

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#612205 - 07/06/2001 19:41 Re: How does the lightning tracker work.
gustfront Offline
Thundergod

Registered: 19/05/2001
Posts: 3393
Loc: North Balgowlah, Sydney, 33.79...
OK Aussie. I see if I can track down some more info for you.

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#612206 - 07/06/2001 19:53 Re: How does the lightning tracker work.
AussieJimbo Offline
Junior Member

Registered: 07/06/2001
Posts: 129
Loc: Canberra
Did a bit of digging. It's clearly a triangulation of some kind of signal.

I'm guessing the system either looks for a particular radio frequency spike or detects something through the ground.

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#612207 - 08/06/2001 00:15 Re: How does the lightning tracker work.
sky Offline
Member

Registered: 10/04/2001
Posts: 180
Does the system detect positive and negative strikes?

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#612208 - 08/06/2001 06:50 Re: How does the lightning tracker work.
Hector Offline
Weatherzone Addict

Registered: 26/01/2001
Posts: 1845
Loc: Melbourne
Hi Jimbo
As a brief explanation, a stroke of lightning acts as an antenna, radiating radio frequencies in a range of frequencies related to the length of the path of the lightning stroke and its duration.
Owing to the long path lengths (of the stroke) for cloud to ground, longer wavelengths and hence lower frequencies are radiated. This means, if you have a long wave radio receiver, you will be able to detect the strokes.
Then, if you have several receivers able to detect strokes, all you need to do is to be able detect the direction of a stroke and triangulate to work out roughly where it is.
This is a very general explanation and I'm sure someone who knows more about the network will provide more details.
Hector

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#612209 - 08/06/2001 14:36 Re: How does the lightning tracker work.
Anonymous
Unregistered


Thats the way it used to work. Triangulation using direction finders is kinda old hat and prone to errors distortions from nearby metallic objects. Some lightning trackers still use that method but most now use a "time-of-arrival" technique. Every lightning strike emits a electromagnetic pulse. If you measure the time the pulse reaches you then that's the "time-of-arrival". If you do this at a bunch of places and compare the different times you can determine where the lightning originated from. You need to measure the time at at least 3 (4 to be sure) places, and you need very accurate clocks (down to the microsecond or less). Lightning trackers are usually set up with a network of antennae all hooked up to a central processor via real-time datalink. The central processor then computes the origin of the lightning strike and transmits it to whoever wants it.
Sorry for the earlier mis-post.

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#612210 - 08/06/2001 16:59 Re: How does the lightning tracker work.
Kattron Offline
Junior Member

Registered: 08/06/2001
Posts: 2
Loc: NSW
When a lightning strike occurs an extremely strong electromagnetic field is generated. Part of the signal produced can be heard on an AM radio receiver when a storm is in the area.

The Kattron network consists of a number of sensors which contain sensitive radio receivers monitoring the 2-450kHz radio band. (This is below the AM Broadcast band.) The sensors digitise the stroke waveform and record details of the stroke including its peak amplitude and polarity, and the time the signal arrived at the sensor (as recorded using the extremely accurate GPS timing signals). The time the signal takes to arrive at a sensor depends on its distance from the stroke. In the diagram below the circles represent the time taken to reach the sensors.



The stroke details are immediately sent via a communications network to a central computer. This computer uses the time of arrival of the signal at the sensor in complex algorithms to determine the location of the stroke. The basic principle is described below.

If two sensors detected the signal from a lightning stroke at the exactly the same time the signal source is a point on a straight line equidistant from both sensors. (See the diagram below).



If the two sensor detected the signal at slightly different times, the signal source is a point on a hyperbola where the distance from each sensor is proportional to the difference in the time of arrival. (See the diagram below).



To determine where along the hyperbola the stroke occurred, a third sensor is required. This third sensor produces a second hyperbola which crosses the first. (See the diagram below) A fourth Sensor adds a third hyperbola and can be used to verify the location of the stroke.



The stroke details are then archived for historical analysis, and transmitted in real time to customers computers where they are displayed on a map.

The whole process from the stroke occurring to itís arrival at a customers site can take less than a few seconds, in some cases all this happens before the thunder is heard by observers. (Thunder takes 3 seconds to travel 1 km.)

Kattron operate a lightning data service using a tracking network called Lightning Positioning And Tracking System ( LPATS ). The Lightning Tracker images are produce with data from the Australian owned and operated Kattron Lightning Detection Network.

The network consists of equipment supplied by Global Atmospherics Inc who manufactured over 95% of the worlds installed lightning detection networks, and who own and operate the North American Lightning Detection Network which is used by organisation including NASA Kennedy Space Centre, NOAA's National Severe Storms Laboratory, Electric Power Research Institute (EPRI) and Universities, along with a wide range of meteorology, aviation, electric power, insurance, and forestry authorities throughout the world.

[This message has been edited by Kattron (edited 08-06-2001).]

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#612211 - 08/06/2001 18:14 Re: How does the lightning tracker work.
AussieJimbo Offline
Junior Member

Registered: 07/06/2001
Posts: 129
Loc: Canberra
Thanks everyone for the great answers. It's very cool technology.



[This message has been edited by AussieJimbo (edited 08-06-2001).]

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#612212 - 09/06/2001 00:53 Re: How does the lightning tracker work.
gustfront Offline
Thundergod

Registered: 19/05/2001
Posts: 3393
Loc: North Balgowlah, Sydney, 33.79...
Thanks for that explanation Kattron. There have also been some questions regarding the accuracy of the system. These questions were raised in this thread
http://beta.weatherzone.com.au/ubb/Forum1/HTML/000264.html

I was wondering if you had any comments to make on the useful accuracy of the information in some of the more remote parts of the country.

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#612213 - 09/06/2001 01:02 Re: How does the lightning tracker work.
Matt Offline
Junior Member

Registered: 10/10/2002
Posts: 1
Loc: Brisbane
Kattron.....how much does the service cost for an individual wanting to recieve live lightning data??

thanks.

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#612214 - 09/06/2001 01:13 Re: How does the lightning tracker work.
Mark Hardy Offline
Weatherzone Addict

Registered: 23/01/2001
Posts: 2881
Loc: North Sydney, NSW
matt, please email us directly and we'll get something to you.
sales@theweather.com.au

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#612215 - 09/06/2001 03:36 Re: How does the lightning tracker work.
Anonymous
Unregistered


Mark Hardy,
Just tried emailing you but was unsuccessful.Are you sure that is the correct email?

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#612216 - 09/06/2001 07:58 Re: How does the lightning tracker work.
Mark Hardy Offline
Weatherzone Addict

Registered: 23/01/2001
Posts: 2881
Loc: North Sydney, NSW
Phil, my email is mhardy@theweather.com.au

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#612217 - 09/06/2001 14:26 Re: How does the lightning tracker work.
Justaminute Offline
Member

Registered: 15/02/2001
Posts: 3649
Loc: Sydney
Great thread this. The explanation from Kattron was excellent as were all replies. Now can some one tell me what system BOM uses for rain & windfinding where TWC get their (r&w) radar from and what is the Takone system that BOM uses for Launceston. I researched this a bit and although I did not get answers to the above I did find this MR which I thought interesting:



23 November 2000

Regional and Rural Australia to benefit from free Bureau Radar Images on the Web
Images from the Bureau of Meteorology's national radar network are now available on the Internet, the Parliamentary Secretary to the Minister for the Environment and Heritage, Dr Sharman Stone, announced today.

"From Monday 27th November, radar images of the weather at 42 sites across the country are a simple mouse-click away. All capital cities are covered by the service, as well as a large number of rural and remote communities", Dr Stone said.

"This sort of information is extremely useful to a very broad cross-section of the community, from farmers to fishermen, to emergency service personnel, tourism operators and even the local cricket association, planning the weekend's fixtures."

"Radar gives a snapshot of areas experiencing rain as well as an estimate of how heavily the rain is falling. This has proved very useful for communities in the grip of extreme weather. The Bowen Shire Council, in Queensland, were able to access this information from the Bureau earlier this year to help prepare for the flooding of the Don River."

"Radar images of hazardous weather, such as tropical cyclones and severe thunderstorms can also be very informative when accompanied by the latest weather warnings from the Bureau. The Bureau's website also carries the latest weather forecast."

Dr Stone said that the Internet was a great way to deliver this kind of real-time, pictorial information to a wide audience.

"The Bureau's web site is one of the most popular of Government sites. During a tropical cyclone, "hit rates" can be as high as 2 million per day."

Phase 1 of the new service is the provision of single images of the latest radar scan at each site. Following this, the Bureau's Internet systems will be carefully monitored to accommodate any extra public demand.

If all goes well, Phase 2 will be implemented by the end of December this year, at which point animated loops of the last three images will also be made available. These are especially useful for tracking the movement of rain-bearing systems. The ongoing availability of radar images will be reviewed from time to time as part of the normal processes that ensure that the Bureau's Internet systems are used most effectively.

"The basic data images will be freely available. Users who want specifically processed or additional radar image info will be asked to meet the costs of any extra work involved.

"We look forward to public feedback on this new service."

The radar images, together with other weather and climate information can be found on the Bureau of Meteorology's website at: www.bom.gov.au.

For further information, please contact:

Simon Frost 0419 495 468 or (02) 6277 2016
Thursday, 23 November 2000


2 million hits per day? That is an incredible number. And it looks as though the BOM again retains the option to charge at a later date. This charging business can be looked at from many perspectives. It is a very interesting subject worth perhaps discussing in another TOPIC of it's own.

Ashton

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#612218 - 09/06/2001 15:17 Re: How does the lightning tracker work.
Anonymous
Unregistered


mark Hardy,
Not sure whats going on, but the email i tried to send will not go thru,must be a problem on my end.
Could you please send pricing information regarding live lightning data to pj@arcom.com.au.
regards...Phil.

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#612219 - 09/06/2001 16:12 Re: How does the lightning tracker work.
Anonymous
Unregistered


Ashton,

The Bom WW and windfind radar are of 2 main types, the S & C band radars also know as WF44 & WF100. Some locations (Canberra & Launceston) still use older WF3 windfind only radars. All the data (WW & windfind) are sent into the Bom HO computer system, the WW in almost real time. TWC I assume (help me out here Mark or Bruce) have the rights to access the data & display on the TWC web site. The West Takone site in Tasmania is just the name location of the NW Tassie WW (only) radar. As to whether the public should pay for access to all Bom services and products is tied up in many areas. The Bom is Federally funded, but has also to "self fund" many programs, and cost retrieval is needed. Consequently not all Bom products are available for free.

Rbl (Wagga)

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#612220 - 09/06/2001 16:47 Re: How does the lightning tracker work.
Justaminute Offline
Member

Registered: 15/02/2001
Posts: 3649
Loc: Sydney
Thank you for taking the time to reply John it sure did put me on track. Takone, here is me thinking Japanese Radar System!!
I'm a Sydney boy John, I'll fall back on that excuse.
I think you will appreciate the fact that I understand the position regarding funding. Unless it develops further I will leave it at that because it really is a political point I am making and probably this is the wrong place. It is not a criticsm of the organisation per se.
In reality my concern is that those "lay people" interested in weather in more than a superficial or self interested way are disadvantaged. I know most data is made available upon request at BOM offices but my arguement would be constructed along the lines of if an organisation is computerised, why not open it up.
Regards

Ashton

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#612221 - 10/06/2001 18:16 Re: How does the lightning tracker work.
O-3 Offline
Weather Freak

Registered: 07/06/2001
Posts: 368
Loc: SA-AUSTRALIA
Sometimes on the lightning tracker there is these little white dots coming up from one of the white current strikes.Does anyone know what these are?....i was thinking maybe heaps of strikes in the one area?

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