Ionosphere Station Information Bulletin**
September 1969

*Under the auspices of the Solar-Terrestrial Physics Committee of the International Union of Radio Science (URSI-STP Committee).
** Issued on behalf of INAG by World Data Center A, Upper Atmosphere Geophysics, Environmental Science Services Administration, Boulder, Colorado, U.S.A., 80302. The Bulletin is distributed to stations by the same channels (but in the reverse direction) as their data ulti-mately flow to WDC-A. Others wishing to be on the distribution list should notify WDC-A.

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3.1 WG Rec.1 Size of Network
3.2 WG Rec.2 Redeployment
3.3 WG Rec.3 High Accuracy Stations
3.4 WG Rec.4 Information Bulletin
3.5 WG Rec.5 Visiting Experts
3.6 WG Rec.10 Centralized Processing of Data
3.7 WG Rec.12 Revised Recommendations for Spread F Parameter
3.8 WG Rec.15 Monitoring of Absorption by Ionosondes
3.9 Rec. (3) New Ionosondes
3.10 Rec. (4) Use of V.I. Data
3.11 Rec. (5) Synoptic Network( for V.I. Soundings
3.12 Rec. (6) Spread F Index

4.1 Rec. (6) Spread F Index
4.2 The parameter fxI
4.2.1 Definition
4.2.2 Scaling Rules
4.3 WG Rec. 12 Revised Recommendations for Spread F Parameter

5.1 WG Rec. 15 Monitoring of Absorption by Ionosondes





1. Introduction

This is the first issue of a bulletin which, if you desire, could continue to serve the stations collaborating in ionosphere research and, in particular, the Vertical Incidence (V.I.) Network.

As some of you may know, the modern era of active coordination of international research on the ionosphere by vertical soundings started with a special regional effort by the International Union for Radio Science (URSI) special Committee on high latitude work which attempted in 1954-55 to obtain uniform interpretation and analysis procedures for the difficult case of high latitude ionograms (URSI Information Bulletin, No. 96, p. 440, 1955). These recommendations laid the groundwork for the much more comprehensive observation, interpretation and analysis methods developed by the URSI Special Committee on the World Wide Soundings (WWSC --popularly known as the Wine Women and Song Committee). The WWSC, appointed in September 1955, undertook this similar work for the whole world and prepared for the cooperative efforts of the International Geophysical Years (IGY 1957-58). The WWSC recommendations have served also for the Inter-national Cooperation Year (IGC 1959) and the International Years of the Quiet Sun (IQSY 1964-65). They continue to be the main basis for the continuing monitoring program coordinated by IUCSTP Working Group 1 and the URSI-STP Committee, in particular for the International years of the Active Sun, 1969-1971.

In the WWSC work the approach was to obtain the opinions of all possible workers in the field at V.I. stations and elsewhere, to balance these using a small expert group and then to explain to the many consult-ants why their suggestions were or were not accepted. As a result it was generally agreed that an acceptable system had been developed and this has been in use ever since. The results of the WWSC work are fully covered in the "Handbook of Ionogram Interpretation and Reduction" by Piggott and Rawer, 1961; this is now out of print but a revised edition is scheduled for the near future. The WWSC was dissolved in 1961 and the continuing needs of the network have been met through the mechanism of an URSI Vertical Incidence Network Consultant to answer queries, give advice and generally report on the condition of the world interchange of ionospheric data. This post has been held by W. R. Piggott, Radio and Space Research Station, Slough, Bucks, England since the dissolution of the WWSC.

At the Munich General Assembly of URSI (1966) it was decided to set up a special working party both to consider and propose answers to questions raised by the Consultative Committee of International Radiocommunications (CCIR) which is the official body, which considers the technical needs of the International Telecommunication Union (I.T.U.), and to identify the needs of the scientific community. Many of us have been involved in this exercise, the results of which were discussed at length in a series of special meet-ings in London in January 1969 and supported by a representative meeting of the URSI-STP Committee held during the URSI General Assembly at Ottawa, August 1969, and will be published in the URSI Information Bulletin. They are also being brought to your attention in this Bulletin.

At the recent meeting of the URSI-STP Committee at Ottawa in August 1969, it was decided that the importance of the network justified the formation of a small advisory group to carry on and extend the work of the V.I. Consultant by providing more help and advice than can be given by a single person. This group is known as the Ionosphere Network Advisory Group (INAG). The names and addresses of the members of this group are as follows:

W. R. Piggott (Chairman)
Radio & Space Res. Station
Ditton Park
Slough, Bucks,

Miss J. V. Lincoln (Secretary)
World Data Center A
Upper Atmosphere Geophysics
Boulder, Colorado, U.S.A., 80302

G. A. M. King
Geophysics Observatory
P.O. Box 2111
Christchurch, New Zealand

Mlle. G. Pillet
Groupe de Recherches Ionospheriques
3, Avenue de la Republique
Issy-les-Moulineaux (Seine), France

Dr. I. Kasuya
Ministry of Posts & Telecommunications
Radio Research Laboratories
2-1 Nukui-Kitamachi 4-Chome
Tokyo 184, Japan

G. M. Stanley
Assoc. Prof. of Geophysics
Geophysical Institute of the University of Alaska
College, Alaska,
U.S.A. 99701

Dr. N. V. Mednikova
P/O Akademgorodok
Moscow Region,

Dr. J. Turner
Ionospheric Prediction Service
Commonwealth Centre
Chifley Square
Sydney NSW, Australia 2000


(ex officio, as Chairman, IUCSTP
Working Group 1)
A. H. Shapley
ESSA Research Laboratories
Boulder, Colorado, U.S.A., 80302

We hope that this group, the INAG, will act up to its initials and NAG the administrations, the users and the unfortunate makers of these data until the data are first class and it is clear to all how and where they are being used. We hope that station observers and others will NAG the INAG in their turn. Let's not be shy!

W.R. Piggott

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2. Description of the Contents of this Bulletin

You have already read the Introduction which traces some of the steps leading up to the formation of the INAG. In the sections which follow, we first give the most important of the recent recommendations concerning Vertical Incidence Soundings and the network, made by or under the auspices of the URSL-STP Committee, which has spent much time (three meetings in less than a year) on these problems. One of their recommendations is for a new parameter (fxI) to aid research and practical studies involving Spread F. So that it will not get lost, we treat this subject in a separate section. For the same reason another separate section contains the URSI-STP comments on improved absorption parameters from V.I. observations. Then we quote some IUCSTP recommendations on V.I. work in conjugate point studies. In the section after this one, we give a provisional answer to "What is the Present Active V.I. Network", and ask your help in correcting and completing the station list attached at the end of this INAG bulletin.

Following this we give a partial list of the reports and books which in the ideal world should be available to each station - and in your own language; these are documents we will refer to from time to time. Then there are some notes from the WDCs - not many this time because there has not been time to approach, let alone to hear from, all the WDCs for material for this bulletin. There is a concluding section on philosophy and on the future of INAG activity. The latter depends on the reaction and response from the world V.I. network. Finally, a footnote with some explanations or apologies about the compilation of this first hurried bulletin, and why it is so hurried.

Following this we give a partial list of the reports and books which in the ideal world should be available to each station - and in your own language; these are documents we will refer to from time to time. Then there are some notes from the WDCs - not many this time because there has not been time to approach, let alone to hear from, all the WDCs for material for this bulletin. There is a concluding section on philosophy and on the future of INAG activity. The latter depends on the reaction and response from the world V.I. network. Finally, a footnote with some explanations or apologies about the compilation of this first hurried bulletin, and why it is so hurried.

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3. Some of the recommendations of URSI-STP Meeting on the Vertical Soundings Network 1969

Copies of the report of the special meeting (London, January 1969) on problems connected with the V. I. Ionospheric Soundings Network have been circulated to all station administrations with copies for all known stations in the network. If you have not received a copy, please write to the Secretary of INAG, Miss J. Virginia Lincoln, World Data Center A, Upper Atmosphere Geophysics, Environmental Science Services Administration, Boulder, Colorado, U.S.A., 80302, who will make sure that you get one and are included in any future circulation. The report is too long for a Bulletin such as this one - 60 pages. We give here some of the main points of interest to stations. As you may know, the half-day meeting itself was attended by some 27 people from 11 countries. It was preceded by a sub-group meeting (many of the same people and others) which was in more or less continuous session over a period of three days during the IUCSTP General Meeting which was preparing for the International Years of the Active Sun, 1969-1971. Even before this there had been rather extensive correspondence and also a detailed questionnaire, in which many of you participated.

The Chairman of the URSI-STP Committee, Prof. W. J. C. Beynon, said there was a clear consensus of this quite broadly representative meeting:

The bulk of the report is comprised of four Appendices, whose titles indicate their scope: Appendix 1. Summary Conclusions and Detailed Recommendations of Ionosonde Network Sub-group of IUCSTP

Appendix 2. "Future of Vertical Incidence Soundings Network," report compiled by Vertical Soundings Consultant, January 15, 1969

Appendix 3. Circular and documents 1-4 issued by Vertical Soundings Consultant

Appendix 4. Collected Comments on Vertical Incidence Soundings Network Of the 15 Recommendations in Appendix 1, the following are of special interest. The others may be treated in a later INAG Bulletin, if any. Here the term "Working Group" (or "WG") is synonymous with the "sub-group" referred to above.

3.1 WG Rec.1 Size of Network

The Working Group noted the views of consultants summarised in the circulated document, considered the use being made at present of data from high, low, and temperate latitude stations, felt that the use fully justifies the maintenance of the existing network at least for the period of the IASY and strongly recommends that stations already operating be maintained for the period.

3.2 WG Rec.2 Redeployment

The Working Group considers that the scientific value of proposals to alter the deployment of stations should be balanced against the cost and recommends the setting up of a small ad hoc group of experts, with knowledge of conditions in widely separated parts of the wor1d, for the following purposes:

3.3 WG Rec.3 High Accuracy Stations

The Working Group draws attention to the need for data with a higher accuracy than is usually obtained at rocket ranges, near Thomson scatter stations and where intensive studies of Solar-terrestrial ionospheric or magnetic problems are active; noted that some investigations using ionosondes demand an accuracy which is only available at one or two stations (e.g., Lindau); and draws attention to the need for a few more stations with this accuracy. The Working Group recommends that action be taken to fill these needs·

The Working Group also stresses the need for synoptic data from these stations, and recommends that such stations be operated regularly and the data obtained circulated even if it is not needed by the particular experimenters involved. In particular, groups using published data on rocket or satellite observations often need to know the synoptic conditions when the observations were made.

3.4 WG Information Bulletin

The Working Group felt a need to improve communication between the stations, the scientists using the data, the International Unions involved, e.g., URSI, TAGA, IUCSTP, and recommends the regular circulation of an Information Bulletin addressed to the stations of the network and all others concerned. The Bulletin should include all International Recommendations involving its recipients, notices of Retrospective World Intervals and other special study periods, information on outstanding Solar-Terrestrial phenomena, discussions on scaling or other problems at stations, suggestions for Regional studies, and notes on new projects or techniques, particularly when they involve interdiscipline cooperation. There should be a section where inexperienced workers could raise their difficulties and request advice. A particular need at present was to interchange information on shipboard and aircraft techniques.

{This bulletin is an attempt to satisfy Rec.4. Your comments would be welcome.]

{And this, of course, was the start of the INAG Bulletin}

3.5 WG Rec.5 Visiting Experts

The WG considers that the most urgent STP requirement is to improve the operation at stations in the existing network which apart from other important uses is valuable for STP monitoring, and recommends:

3.6 WG Rec.10 Centralized Processing of Data

The Working Group feels that centralization of some steps in the handling of data from stations is rapidly becoming essential since all the data will be needed in computer compatible form and it is inefficient and inaccurate to process data by hand when it will eventually be computerised. The Working Group recommends that all organizations having access to computer processing should use it both for interchange and, where desired, for the production of tables.

3.7 WG Rec.12 Revised Recommendations for Spread F Parameter

(See Section IV of this INAG bulletin for full text)

3.8 WG Rec.15 Monitoring of Absorption by Ionosondes

(See Section V of this INAG bulletin for full text)

Another group of recommendations made originally by the URSI-STP Committee at an earlier (Brussels, September 1968) meeting was supported by the London sub-group of V.I. specialists. To keep things straight, we identify them here as Br (Brussels) Recommendation. Here are some of them:

3.9 Rec. (3) New Ionosondes

The URST-STP Committee draws attention to the fact that the Ionosondes in use at many synoptic stations are obsolete, or wearing out, or both, and that there is an urgent need to provide for their replacement by modern equipment

Depending on local conditions, the main requirements are for:

3.10 Rec. (4) Use of V.I. Data

The URSI-STP Committee requests those using synoptic data for scientific purposes to send copies of any published papers or preprints to the administrations responsible for producing the original data.

3.11 Rec. (5) Synoptic Network for V.I. Soundings

The URSI-STP Committee, having considered the views of those who produce and use vertical incidence soundings data, recommends that all V.I. Stations be encouraged to participate in intensive studies of regional and other problems and that a strong effort be made to increase the degree of flexibility in the V.I. network to meet the changing needs of inter-national cooperation and of coordination with space experiments. The URSI-STP Committee further recommends that a number of stations be identified by consultation with countries interested in the possibility of developing these stations to meet high standards of qualitv at a limited number of locations.

3.12 Rec. (6) Spread F Index

(See Section IV of this INAG bulletin for full text)

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4. Spread F Index - A New Parameter, fxI

As noted above, the URSI-STP Committee (Brussels, September .1968) has recommended the introduction of a new parameter which will give a measure of Spread F. The full text on this matter is given here; but note that the London Working Group revised and extended this recommendation in their WG Rec. 12, which given at the end of this section.*

4.1 Rec. (6) Spread F Index

The URSI-STP Committee, noting that a measure of the top frequency of Spread F is urgently required for CCIR purposes and also has scientific interest and that a proposal to introduce such an index has been widely supported by those responsible for stations, recommends that a new ionospheric parameter denoted fxI (with computer symbol 51) be adopted for international analysis, tabulation and normal circulation through WDCs and other publication methods, defined and applied according to the instructions following. It is recommended that all stations at high latitudes or subject to equatorial spread F tabulate and circulate this parameter, and that stations at other latitudes be invited to volunteer to analyse the parameter as a trial. Tests are particularly important at stations where the spread of frequencies of spread F often exceeds fH/2 at certain hours.

The URSI-STP Committee further recommends that stations report the properties of the new parameter in the scientific literature, through STP Notes, or through the URSI V.I. Consultant (Mr. W. R. Piggott, Radio and Space Research Station, Slough, Bucks., U.K.), and that its operation be reviewed at the next General Assembly of URSI where any suggested modifications can be considered and approved. It is recommended that this resolution be brought to the attention of CCIR, who should request administrations to adopt this index

4.2 The parameter fxI

4.2.1 Definition

The parameter fxI is defined as the highest frequency on which reflections from the F region are recorded, independent of whether they are reflected overhead or at oblique incidence. Thus, fxI is the top frequency of spread F traces including polar or equatorial spurs, but not including ground backscatter traces.

4.2.2 Scaling Rules

4.3 WG Rec. 12 Revised Recommendations for Spread F Parameter

The Working Group endorses the proposal to establish a new international index for spread F (URSI Bulletin No. 169, December 1968, URSI-STP Rec. 6, p. 56) and discussed details of rules for this index and for the interchange of related parameters which may be circulated in the future, It was concluded that some confusion of the originally suggested nomenclature with the satellite parameter fxS (extraordinary mode plasma frequency at the satellite) was likely and that the nomenclature should be changed to avoid this. The Working Group recommends the following changes and additions to URSI-STP Rec. 6:

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5. Improved Absorption Parameters?

The London sub-group spent a long time discussing both the need for and the possibilities of obtaining better measures of ionospheric absorption from ionosonde observations. The result was the following recommendation:

5.1 WG Rec. 15 Monitoring of Absorption by Ionosondes

The Working Group notes that the variation of absorption with position and time appears to be more complicated than can be adequately monitored by existing absorption stations and recommends that all V.I. stations attempt to produce a parameter, which is dependent on the absorption present.

The following techniques can be used to obtain on improved measure of absorption for synoptic purposes and the Working Group recommends that they be adopted, as appropriate.

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6. Ionosondes in Conjugate Point Studies

Some pertinent recommendations have been made by Working Group 5, on Conjugate Point Experiments, of the Interunion Commission on Solar Terrestrial Physics (IUCSTP). Background information and details appear in STP Notes No. 1, 2 and 3. Of particular interest is General Recommendation No. 15 (proposed by WG 5) of the London, January 1969, meeting of IUCSTP as follows (STP Notes No. 4, page 26):

"Recognizing that comprehensive studies of the conjugate behaviour, of the ionosphere require continuous records from an extensive network of ground stations,


Urges that operation of the world-wide ionosonde station network be continued, and that existing gaps in conjugate coverage be remedied, whenever possible, with the establishment of new, conveniently located stations.

Further, IUCSTP Working Group 5 made on its own authority several specific recommendations about new measurements needed at some stations, or desirable locations for important new work. One such recommendation which mentions an ionosonde is as follows (STP Notes No. 4, page 62, WG recommendation (6)



Recommends that a station, equipped with a photometer and eventually an ionosonde, be set up as close as possible to the theoretical conjugate point of Arecibo."

These IUCSTP actions are noted here to give an indication of the interest in the V.I. work of scientists in other fields of solar terrestrial research, scientists who are not themselves engaged in V.I. observations but who are users of the data in their researches.

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7. What is the Present Active V.I. Network?

STP Notes No. 6, a special issue, is in press as this is being written. In addition to the "Guide for International Exchange of Data in Solar Terrestrial Physics (1969)", it also contains "Provisional Lists of Observing Stations for the International Years of the Active Sun (IASY) 1969-1971". These lists compiled from national reports to IUCSTP, from the most recent WDC catalogs and from information received less formally by IUCSTP, represents the best available list of active stations in the disciplines covered. We reproduce the list for Ionospheric Vertical Soundings (Program B.l) as an Appendix to this INAG bulletin. Yet members of INAG know, very informally, that a number of other stations are in operation. Some of these "lost" stations run regularly or quite regularly, others operate on an intermittent basis. We would especially appreciate it if recipients of this INAG bulletin would help make the list of V.I. stations correct and complete. Please write to the INAG Secretary or to any member. Corrections to station coordinates would also be most helpful.

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8. List of Useful Reference Materials

Here is a recapitulation of some of the useful reports and documents which the INAG hopes are available to or at each station. If everyone has the same reference material, we have gone a long way towards achieving a useful degree of uniformity in observation, interpretation and analysis. Some of the material is rather old, but should still be valuable. Other items are new (some only just now being issued) and will not yet have reached stations, In the course of the next year we would hope that all of these reference materials will be available to each station. We will reprint and extend this list in future (if any) issues of these INAG bulletins.

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9. Philosophy and Future

This bulletin quotes recommendations by authoritative international scientific groups. However it should be clearly understood that they are only recommendations, made with the hope of increasing the value of the work in scientific research and technical activities. We are calling them to your attention so that you can know the international standards, and can ask for advice or help when needed. You should note that the international advisory group, INAG, is not responsible for your station. INAG should not, cannot and does not give "instructions". Sometimes there are local needs or difficulties which are best met by departing from these international "rules" or recommendations. Thus, you should never alter the procedure you are using without first asking permission of your administration. At the same time, sometimes departure from the inter-national "standard" has been unintentional. Frequent changes in staff do unavoidably result in gradual changes in procedures and methods. It is hoped that INAG and this information bulletin will help to check this. The members of INAG are anxious to help. Please write to any member, or to the INAG secretary, with any questions or suggestions or information. Please write anyway to give your opinion on whether and what INAG should undertake. Its future activities will be based on the response during the coming months.

(Note: This first INAG bulletin is· being issued before there has been time for all INAG members to exchange their ideas by correspondence. There was, however, an informal meeting at Ottawa at the end of August of four members and people who are close to three others; among these there was a good consensus on how to start - and start we have.)

This group thought that if we were going to try out the mechanism of an information bulletin, we should try to start it in time to reach (translated if possible) the loneliest and most isolated of us all, the observers at Antarctic stations before their expeditions set sail this (Austral) summer. So we have compiled this first effort in something of a hurry. In fact, in the week after the URSI Assembly several of the substantive sections were put together in the full tradition of the WWSC (see page 1) during a meeting on ionospheric forecasting in Canada where the timely use of V.I. data was one of the important serious topics.. Thus, started by Piggott, Pillet and Lincoln, the completion was by the Boulder addressees, with "ex officio" taking ultimate responsibility and blame in the absence of the Secretary in Geneva at CCIR Study Group VI, where the V.I. network, its health and well being is again a prominent topic.

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