Propagation between Persian Gulf & Darwin

[VK4WDM]

Last night VK8AW reported very strong signals between Darwin and the Persian Gulf. The opening did not appear to extend across to Nth QLD (although I did a very weak response to a CQ which sounded like a non-Asia accent) nor did it appear to extend south into WA.

There was a huge TEP opening between most of VK and Asia yesterday that lasted, up here at least, for around 12 hours.

My question is: What sort of propagation enabled the Gulf to VK8 pipeline and why was the footprint so small?

Please respect others opinions and give reasons for your answers so that all of us, but especially the newbies to 6m. might learn something useful about the peculiarities of the "magic band."

73

Wayne VK4WDM

[VK3ZAZ]

According to one theory the K6FV model it relates to extension via intense local es down equator under the local noon mean time sun
not unlike prop that I experienced from VK9XI daily in 2003 to VQ9 JY 4X4 A4 A6
It will not likely extend down to your latitude with extra hops thousands k further on,
to confirm that you need to plot your path to the region and compare it with VK8 path.
I have the graphs of the plots of e layer and F hops but they are on old celluloide OHT's
The 12 hour N S TEP is not related to West prop from VK8 IMO
and in the absence of VK6PA and JQ at Broome we can but speculate where else the path ends up.

Does anyone have any sounder data west from VK to confirm or otherwise the soundings above,
including that from Indian Ocean islands Indonesia and Chagos and Seychelles?

[VK8MS]

Hi Wayne,
This path is so regular that we take it for granted we have had this path open since mid February which extends until late April early may then path again September-November which is equatorial anomoly or TEP although the signals we see are 5x9++ may be there is some "F" & "E" components when we have it solid S-9+, .
I have lived in Darwin for 25 years and have seen this TEP happen same time every year and the signals end of march peak well over S-9 but then take a dramatic dive like last night with most stations back to S-4 to 7 with fluctuations which is a characteristic of TEP, also may be when its steady at such high signal levels there is some choroidal path not sure as its beyond my knowledge.

Since mid Feb. we have regularly worked A71,A92,A61,9K2 etc which all of this is pre-empted with our afternoon TEP to KH6,V73 etc, if you hear either east or west path seem to guarantee you will either hear other path that same day or next day.

Also for the last week we have been able to work KH6SX and 9K2,A71 etc at same time of day at 1000z

In summary "my own opinion" is majority of time these paths are TEP.

Mark - VK8MS.

[VK4WDM]

Hi Mark and Steve

Mark, interesting thought. Very low angle for TEP I would think but the JA's were working into Africa a few months ago and there was also a question whether that was TEP also.

Steve, If you are correct the next "hop" could be right over the top of northern VK and end up in the hamless Pacific ocean. Fascinating stuff!

73

Wayne VK4WDM

[VK3AUU]

If you had been watching the TEC map, you would have seen that the path was most likely TEP type. The TEC plot was interesting during the day as it was unusually high. The path probably didn't extend any further east.

David

[VK4WDM]

Good point David. How many more TEP pathways deviate from the "traditional" Mid BA - KH6 spread?

How can we use TEC and other propagation tools to predict these? Perhaps a tutorial on their use should be published in AR Mag?

If TEP happens between the Persian Gulf and Northern VK does it also occur between W6/W7 and VK at the same angle?

73

Wayne VK4WDM

[VK3AUU]

Roger VK2ZRH has already written copiously on the subject.
http://home.iprimus.com.au/toddemslie/eTEP-Harrison.htm
http://www.qsl.net/vk2kfj/tep.html
also see
http://www.ips.gov.au/Satellite/2/1/5
to see where the reflecting medium was located (updated hourly)
The signals don't hit the ground between the peaks, only at each end and if there is Es that may extent the path further. That seems to be why you lot up there get JA but we miss out unless there is also some Es.

No doubt Roger will correct me if I am wrong


David

[VK2ZRH]

Hi David, Wayne and Others.

No need to correct you David; all good.

Everyone will find more enlightenment here, too: http://www.vklogger.com/forum/viewtopic ... 62&p=41904

[VK3AUU]

It would be good if someone could take screen shot of the TEC chart at the time these contacts are taking place. They generally seem to be an hour behind. If I am up around midnight I will do so.

David

[VK4WDM]

3B9 was working JA yesterday presumably via same type of propagation as ME to VK8. The roughly same angle across the equator and distance would put eastern VK into NA but this does not seem to happen? Why?

73

Wayne VK4WDM

[VK3AUU]

You would have to look at the TEC plots for the day. These paths are pretty marginal, so things have to be all lining up appropriately, including whether there is also some Es in the right place.
David

[VK3AUU]

The attached TEC plot shows how VK8AW to KH6 happened. VK8 to 1st cloud, across to 2nd cloud then back to ground at KH6.
David

[VK6SIX]

"3B9 was working JA yesterday presumably via same type of propagation as ME to VK8."

Gday Wayne.

The jas have had a path to ZS8/3B8/3B9 etc for many years around 0800 utc onwards approx during peaks or equinox etc.

One day years ago we had jas into perth for many hours on 110 ssb while they were working ZS8 marion island,... but not 1 out of thousands of jas mentioned that it was ZS8.

A local perth ham had to work a ja to find out who they were working.

And it went on for a few days same time etc.

Sometimes i reckon you can see the path on the http://iono.jpl.nasa.gov//latest_rti_global.html chart.

cheers

vk6six

e&oe