Introduction
This short note briefly sketches the history of the operation of ionosondes in South Africa and Namibia. It also discusses the various types of ionosondes used in the past and those available for use at present. The current situation is cause for concern to ionospheric researchers and local operators of HF communications equipment. A more optimistic long term scenario with mutually beneficial cooperation between states in Southern Africa, and possibly further North in Africa, is described.
One of the problems in preparing a review such as this is the paucity of information readily available on the establishment and subsequent history of ionospheric stations. It is believed that South Africa is not unique in this regard. Operators of ionosonde stations are urged to record the history and main events at the stations at the same time for future reference.
Historical Review
National Institute for Telecommunications Research (NITR)
The provision of HF predictions in South Africa dates back to the Second World War. The earliest published reference to a continuing HF prediction service during the post-war years is dated 1947 [1].
The first ionospheric station in South Africa for synoptic studies was established near the Johannesburg city centre in May 1946. Regular ionospheric data were, however, recorded at Durbanville, near Cape Town, from September 1944 to January 1946 [1]. An ionogram sample from the first ionosonde is shown here. It is the first ionogram recorded with the Wadley ionosonde [2] at the University of the Witwatersraand [3]. (The contrast has been enhanced using digital image processing.)The equipment at Johannesburg was a single sweep pulse ionosonde which was developed locally [1,2] by Dr Trevor Wadley, the inventor of the Tellurometer, at the Telecommunications Research Laboratory (later the NITR) of the Council for Scientific and Industrial Research (CSIR). Figure 1 [3] shows the first ionogram recorded with the Wadley ionosonde at the University of the Witwatersrand, Johannesburg on the 9th of April, 1946. After several years this station was moved to Frankenwald, about 18 kilometres to the north-northeast. A second station for regular synoptic studies was established near Cape Town during 1948 [2]. It was equipped with similar equipment to that at Johannnesburg. Antennas used at both stations were multiple vertical rhombics on a 60-metre lattice mast made of pieces of creosoted pine timber. Both stations were operated by the NITR of the CSIR. The NITR was recently incorporated into the MIKOMTEK Division of the CSIR in Pretoria during reorganisation of the Council.
At the beginning of May 1971, the station near Cape Town was relocated to the Magnetic Observatory at Hermanus, approximately 100 kilometres to the southeast. One of the reasons was that the original lattice mast had become unserviceable - this after about twenty years with minimal maintenance. Bearing in mind the coastal climate, this is a remarkable testimony to the durability of wooden creosoted masts.
During 1981 the ionosonde at Frankenwald, by now extensively modified but still retaining many of the old valve components and still operational after some 35 or so years, was replaced by a KEL 42 ionosonde. A BR Comms. chirp ionosonde (Chirpsounder) was purchased for use in a vertical incidence and oblique sounding program during the mid 1980's, but not implemented for various reasons. The ionosonde at Hermanus had been replaced by a locally developed transistorised one during the 1970's. During 1982 this station was also equipped with a KEL 42 ionosonde.
The Johannesburg and Hermanus stations continued in operation until March, 1993 when they were essentially mothballed due to lack of operating funds.
The NITR also established an ionospheric station on Marion Island, in the South Indian Ocean, during the IGY of 1957/1958. The ionosonde was manufactured by COSSOR of Canada. The station on Marion Island was temporarily re-opened sometime during 1972 using a locally developed transistorised ionosonde. The station operated with variable reliability till May 1980 when it was closed.
In addition to the above, NITR also took over some of the responsibilities for the running of the station at Tsumeb, in Namibia, during the 1970's.
Rhodes University, Grahamstown
As far as can be established, the first use of ionosondes for ionospheric research at Rhodes University, Grahamstown, dates back to the mid 1940's when a home-built instrument was used to study the partial eclipse of the sun on 14 January 1945 [4].
The Physics Department at Rhodes University in Grahamstown established an ionospheric research station there during the 1957/58 IGY. Members of the Department using plans for the original ionosonde developed by the NITR [2] built the equipment. The station operated intermittently for a number of years for research purposes and has been operating on a regular synoptic basis since July 1972. The current equipment is a BR Comms. Chirpsounder that has been modified and improved with guidance from Dr Allon Poole [5,6]. This station is currently the only one operating on a regular basis in South Africa.
During 1962 Rhodes University's Department of Physics began its Antarctic ionospheric research program when a sounder was installed at Sanae Base in Antarctica by the author. Establishment of the station took place at the same time as the new base was being built. Consequently the first ionograms were only observed during June of that year using the refurbished COSSOR ionosonde, which had originally been installed by the NITR on Marion Island. This ionosonde was used until April 1975, when a BR Comms. Chirpsounder was installed. This made it possible to make oblique soundings between Sanae and Grahamstown. These oblique soundings were phased out during 1987. Ionospheric observations at Sanae were discontinued in February 1990. Information on the Antarctic research program and a discussion of other local ionospheric research efforts can be found in articles by Gledhill [7] and Poole [8].
At present ionospheric research at Rhodes University is conducted by the Hermann Ohlthaver Institute for Aeronomy, with Dr Allon Poole as its Director.
Tsumeb, Namibia
From about 1964 the Max Planck Institute for Aeronomy in Germany operated an ionospheric station at Tsumeb. Apart from an involvement with the running of the station and data handling in the late 1970's by the NITR, this station operated independently. As far as can be established this station continued in operation until mid to late 1980's.
Present Status
Operations of the Johannesburg and Hermanus stations were discontinued by MIKOMTEK in March 1993 for financial reasons. The stations can be operated on request. At present the only active station that can be used for synoptic data, is the one at Grahamstown. Ionospheric research at both Rhodes University and the University of Pretoria are continuing, but at a relatively low level.
There are no modern fully automated ionosondes available in South Africa at present. Researchers are thus unable to participate in research requiring a reasonable level of sophistication. The manpower and funding situation is such that even reduction of ionograms to participate in the URSI Working Group G4 of Commission G on the Vertical Incidence Modelling (VIM) project, is out of the question.
There are many reasons for the declining support for and interest in ionospheric research. Some of the more obvious ones include the dramatic political changes in Southern Africa as a whole following changes in the USSR, and in South Africa itself as a result of new political initiatives here. There has therefore been a general rethink on the national scientific and social priorities pending a new political dispensation. Generally there also appears to be the perception that HF systems represent dated technology and as such it has fallen out of favour. It is also a fact that research and development funds in South Africa compare poorly with those of many other countries. Consequently competition for available funds is very keen.
Future Prospects
From discussions with various colleagues, it appears clear that ionospheric research can only be undertaken in future if this can be done in support of commercial ventures or political initiatives and cooperation in the subcontinent.
Commercial ventures include the development and evaluation of a variety of HF communications equipment, especially digital modems. Other possibilities are the support of near real-time frequency management systems, automatic HF link establishment and SSL HFDF systems. While some countries can also justify the continued operation of ionosondes in support of OTH HF radar systems, this option appears to be highly unlikely in the Southern African context.
With the rapidly changing political situation in South Africa comes a renewed awareness of the technological assistance that can be offered to neighbouring countries. Although HF communications are seen by many to be of limited use, this is probably still the cheapest means of communication in Africa. Many countries in Africa have a potentially viable HF communications infrastructure because of the amount of HF equipment already available for use by them. This offers an ideal opportunity for South Africa to assist these countries to maximise the potential benefits of such an HF infrastructure by providing advice on the whole spectrum of HF communications, including antennas and propagation.
Other options, which could be explored in terms of cooperative ventures, include SSL HFDF and improved HF predictions in support of policing and conservation activities. There is no reason why mutually beneficial initiatives aimed at search and rescue operations and reducing the smuggling of arms, drugs and products from endangered species, could not become a standard feature of the changing circumstances in Southern Africa.
Conclusion
The immediate future for ionospheric research in South Africa is not particularly bright. As with many other areas of research, priorities will ultimately be determined by the politics of the region and the potential visible benefits to the community at large. The higher priorities of social reconstruction are expected to impact directly on the amount of money available for research and thus to seriously test the levels of research commitment.
At present it is almost impossible for South Africa to make any contribution to international research programs, such as the VIM program, with the currently available ionosondes.
As the political climate changes and more contact becomes possible with neighbouring countries, the possibility of cooperating with and providing these countries with technological expertise becomes a very real and exciting prospect. Perhaps if this could be achieved, even in some small measure, this will ensure the continued survival of ionospheric research activities at the Universities of Rhodes and Pretoria, and at the CSIR.
Acknowledgements
The author gratefully acknowledges the assistance of the MIKOMTEK Division of the CSIR in Pretoria in tracing some of the history of the ionospheric programmes managed by the NITR. The assistance of Dr Allon Poole, current Director of the Hermann Olthaver Institute for Aeronomy at Rhodes University, Grahamstown, for the supply, verification and correction of information relating to the ionospheric research activities at Rhodes University, is acknowledged with sincere thanks and appreciation.
References
- F J Hewitt, (Miss) J Hewitt and T L Wadley, A frequency prediction service for South Africa, Trans. SAIEE, Vol. 38, pp. 180-197, July 1947.
- T L Wadley, A single-band 0-20-Mc/s ionosphere recorder embodying some new techniques, Proc. Instn. Elect. Engrs., Pt. III, Vol. 96, pp. 483-486, 1949.
- C C Mercer, The search for an ionospheric model suitable for real-time applications in HF radio communications, MSc thesis, Rhodes University, Grahamstown, South Africa.
- J A Gledhill and M E Szendrei, The behaviour of the F-region of the ionosphere over Grahamstown during the solar eclipse of the 14th January 1945, Trans. Roy. Soc. S. Africa, Vol. 31, pp. 147-152, 1947.
- A W V Poole, Advanced sounding: (i) The FMCW alternative, Radio Sci., Vol. 20, pp. 1609-1616, 1985.
- A W V Poole and G P Evans, Advanced sounding: (ii) First results from an advanced chirp ionosonde, Radio Sci., Vol. 20, pp. 1617-1623, 1985.
- J A Gledhill, Thirty years of upper atmosphere research work at Rhodes, Part I, The Radio Scientist, Vol. 2, pp. 106-112, 1991.
- A W V Poole, Thirty years of upper atmosphere research work at Rhodes, Part II, The Radio Scientist, Vol. 2, pp. 112-114, 1991.