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Hadley Cell Propagation

Discussion of results

Volker Grassmann, DF5AI

last update: April 15, 2006


The page documents the readers' feedback on the article Hadley Cell Propagation and provides additional information on the dx observations discussed therein. If you wish to contribute personal thoughts, ideas and comments please contact the author by referring to the contact section of the DF5AI.NET web site.

Email from Gene, W3ZZ, February 4, 2006 (referring to the paper's manuscript)

I think you have provided an excellent description of why the horse latitudes - your Hadley Cell regions - support long lived ducting. While it may be obvious to some of us who have thought about it for a long time, it is not at all obvious to many hams so you have done them a service.

You might want to preface this paper with a comment on your web site calling it a work in progress - and begging readers who have knowledge of >3000 km tropo contacts especially in other than the Hawaiin or Europe-West Africa ducts - to please come forward.

Under 2. The QSO database paragraph 1: The quantitative data you present has too be quite inaccurate because most of the contacts in the most popular duct, US-KH6, is much too low. There is no way you can find all of this data - most of it never appeared anywhere and there are no long term records. Clearly the number 100 is only a fraction of the number of contacts over 3000 km. You in fact agree that it is too low later in the paper. There are a couple of ways out of this problem. You can say that Table 2.1 is representative of the different paths that have been described in print but of course cannot provide the actual number of times each path has been worked, especially for the Hawaiian duct. You can try to get an actual estimate by trying to get data from KH6HME's logs realising that other KH6's like KH6SX also work the duct. Or rather than trying to estimate the total number of QSOs on all paths for all years - I think this is impossible to do - you might list the known paths and present Table 2.1 by path and by year with each path and call the table representative of the QSOs made on those paths. If you do the latter, your tables on numbers of QSOs would not be particularly meaningful.


Among the other possible paths: PY7 [very eastern Brazil]/PY0 to ZD8 has already been heard but I believe by commercial stations. ZL3NE says in his paper that VK6 to the Chatham Islands (ZL/C) exists: "The early propagation here usually comes from very long ducts travelling under jet wind streams. I have recorded them out to 5000 km long, from Darwin to over the Chatham Islands.. " You might want to ask him if he has any evidence that two amateur stations have worked over the VK-ZL/C path. [Editor's note: I did contact Bob, ZL3NE, who states that no dx contacts have been made by resident amateurs on Chatham Islands (email from Feb 5, 2006)]

Finally you might want to contact Bob Cooper ZL4AAA for a review. He is in my opinion the world's greatest TV DXer and one of the world's great experts on tropospheric propagation. I am attaching a column that he wrote for me on transatlantic ducting. Should you wish to contact him, his Email is ... [Editor's note: the email address has been blanked out in order to prevent misuse by email spamming. I have approached Bob, ZL4AAA, but I haven't yet received feedback]

I am sorry to provide so much new information that it may delay your publication on the website. But this is a rare opportunity to discuss a very interesting topic and getting all the information is very difficult. I especially think that ZL4AAA will provide a useful review if he has time to do it.

[Editor's note: You will find Gene's comments considered in the final paper. Gene, thank you very much indeed for support, assistance and valuable contributions - you comments are very much appreciated, always.]

Email from Don, VK6HK, February 23, 2006 addressing Philippe, FR5DN

The purpose of this mail is to draw your attention to an article in preparation by DF5AI about VHF DX tropospheric propagation worldwide which is shown in the link below.

In the article DF5AI highlights the reported reception on Reunion by Yvon FR1GZ of the VK6RBU beacon on 144.560 MHz some years ago. This was of course welcomed at the time and then and now is of great interest to those of us interested in this sort of thing.

However in view of the considerable emphasis that DF5AI has given the report I believe that it is important to let him know the details of the event at the time, but in doing that I wanted to make sure that you and Yvon were also fully aware of what was going on and that you also had an opportunity to comment.

From this end it is simple enough. I understand that FR1GZ reported that he believed he had received the VK6RBU transmission on two occasions (on May 30 and June 4 1996), but was not able (or qualified?) at the time to positively identify the transmission's FSK ident in morse code. Later you and I (FR5DN and VK6HK) had a contact on 14 MHz to which FR1GZ listened and I played a tape recording of the ident with explanation. As a result, Yvon FR1GZ reported via you (FR5DN) that "that was what he heard" (on 144 from VK6RBU).

This is not to say that FR1GZ did not hear VK6RBU but only that in the normal way of confirming "SWL" reception or a QSO that the report probably doesn't count and that may affect the way DF5AI reports the result!

I think that the best way to sort this out is for you to contact DF5AI direct or vice versa and discuss the matter by email.

By the way, VK6RBU is still operating on 144.558 MHz (its drifted a little as the crystal has aged) and has been so operating with little interruption for all those intervening 10 years. There have been no further DX reports of reception from the west, although it is continually audible in Perth at about 160Km off the side of the beam.

I have copied this mail to DF5AI, VK2KRR and VK6KZ.

All this said, DF5AI's article makes very interesting reading and maintains the hope that one of these days a two way 2mx contact between Reunion and Australia will happen!

[Editor's note: Thank you very much indeed for this important contribution. Don and I, we haven't yet figured out the details of this 6.000 kilometers dx observation made by Yvon, FR1GZ.]


Don's latest email, February 24, 2006:

It seems that there is a problem with the ISP as I also have had my emails rejected from both FR5DN and FR1GZ, so I have resorted to sending FR5DN a copy of the email by post! I do want to keep them in the loop.

It is clear of course that it is impossible to expect that the limited number of stations at each end of the Reunion- Australia path can monitor at all times and I have pondered the possibility of setting up some sort of automatic system but it has not progressed.

Following the 1996 report we did encourage the FR people to establish a beacon and offered to provide a transmitter crystalled to their allocated frequency, with keyer programmed to their callsign but there were problems of finding a site and I think licensing. They certainly tried to overcome the problems but it came to nothing. Having been connected with most of the VHF beacons in VK6 over the years I can appreciate the problems of setting one up while keeping expenses to a practical level!

I do subscribe to DUBUS so will no doubt see your paper in print shortly.

We also have a very experienced and competent TV SWL here in Tony Mann whose website is:

You may find his efforts interesting, especially his UHF TV DX reception of YB TV stations in VK6 over 3000 Km N-S. I have discussed with Tony the possibility of looking for Reunion or Mauritius TV carriers but I think I am correct in recalling that his research could not locate a suitable transmitter to monitor either because of a poor location, directional antenna or not having a clear channel.

[Editor's note: The readers are requested to visit this interesting web site. I have been active with 50-90 MHz TV dxing for many yeras. In those days, the 50 MHz amateur radio band was not available to German ham operators, i.e. TV transmitters filled the gap between 28 and 144 MHz.]

Email from Leigh, VK2KRR, February 24, 2006

I have written a response to your excellent Hadley Cell Propagation discussion paper. I have gone through and outlined my thoughts on a few of your chapters in the paper.

Hadley Cell Propagation - Discussion response: SpecialTopics1d (PDF, 2.9 MB)

[Editor's note: Leigh discusses his personals experience in tropospheric very long distance propagation in Australia, presents weather charts, statistical analyses of long dx band openings and reflects on the nature of troposheric inversion layers causing ducting of radiowaves. Leigh, thanks for this excellent feedback.]

Email from Phil, FR5DN, March 14, 2006

Hi Volker,

I have got a letter from Don, VK6HK, abt the VHF long distance qso article that you are preparing. No qso has been made between FR and VK yet. Yvon FR1GZ did get a copy of VK6RBU some 10 years ago on 144.560.

I will get contact with Yvon and try to find out if he still has all data of the both RX he had from the beacon.

More details will follow as time permits.

Congrats for your excellent data page on VHF DX.
Vy73 - Phil -FR5DN

Email from Carlos, N4IS, April 1, 2006

The Hadley cell propagation got my attention in relation with the recent TEP activity going on in Brazil. Not only taking in consideration we are in the low solar cycle but the geometry of the QSO's between FJ5 and PY5, PP5, the center point of those QSO's are in the geographic equator and not on the magnet equator as we can expect during TEP.

I think there are a lot of data available in the PY's and FJ 8P6 logs, including a recent 144 MHz PY2ANE copy of FJ5 in SPaulo, this never happened before, so we can grab all qso's information in one log providing a huge source for further studies to understand if this unusual path on 144Mhz is related with Hadley cell or it is TEP or just Es.

Flavio, Luiz could your VHF group put together a log reporting all activities on 144 MHz in the last six month between Brazil and Caribbean? With this data we can check it against Hadley convention cells due the fact there are formed around the geographic equator.

Another fact that makes me think about that it, is the low activity on 144 MHz between KP4 and LU during the same period. If TEP is strong enough to provide PY - FJ path, why KP4 and LU path is not strong as it should be?

Carlos Silva


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