No. 199 NAI TSCH/3/S15499
Memorandum for Government by the Department of Industry and Commerce
'Exchange of Meteorological Data between Ireland and Britain in case of War'
(Secret)
Dublin, 8 May 1953
- The British Embassy have enquired informally as to whether we would agree in principle to make a reciprocal arrangement with the British Authorities for the exchange of meteorological reports in the event of the outbreak of war.
- An exchange arrangement which was approved by the Government in August, 1939, operated throughout the recent World War. Although circumstances have changed considerably since 1939 (e.g., we now have a fully competent staff of weather forecasters, whereas in 1939 we were dependent on officers on loan from Great Britain), it is considered essential, for the reasons given below, that a similar arrangement should be operated if war breaks out again. It is therefore proposed that we should agree in principle to the British suggestion.
- The indispensable basis on which all scientific weather forecasts are founded is the ‘synoptic chart’ which is an up-to-date map of the actual weather situation and is prepared anew at frequent intervals, normally of three or six hours. The completed synoptic chart is a synthesis of a very large number of actual weather reports made simultaneously at observing points all over the world, transmitted rapidly to the different forecasting centres and plotted by means of special symbols on the appropriate charts. Without these actual weather reports, it would be impossible to draw up synoptic charts, which are the basic tool of the forecaster.
- The completion of synoptic charts in Ireland requires data from that portion of the Northern Hemisphere lying between the Rocky Mountains and the USSR.
The peace-time organisation for the international exchange of weather reports within this area, so far as it affects Ireland, may be summarised as follows:-
- Incoming data:
The weather reports for North America and the North Atlantic come on radioteletype (RTT) channels via the Azores to Paris. Thence it is transferred to a teletype channel via London (Dunstable) to Dublin and Shannon. (In order to gain valuable time, the RTT transmission from Azores to Paris is in practice intercepted at Shannon whenever this is possible.)
The weather reports from Britain, Continental Europe and North Africa come on teletype channels via London (Dunstable) to Dublin and Shannon.
- Outgoing data:
The weather reports of the Irish Meteorological Service are sent on radioteletype channels via the Azores to North America and North Africa, and on teletype channels via London to Europe.
The volume of incoming data is many hundred times greater than that of outgoing data, which consists of weather reports from eleven Irish surface stations and one upper-air station, together with occasional reports from Irish merchant ships in the Eastern North Atlantic. The upper-air station is at Valentia Observatory, Cahirciveen; half the cost of making these upper-air reports is borne by the British.
- Incoming data:
- War affecting our area would lead to the immediate breakdown of the peace-time organisation for international co-operation in this matter. The exchange of weather information (which, in this aviation age, becomes a wartime secret) must necessarily be arranged on a bilateral or multilateral basis between Governments.
- It may be mentioned that whereas the Irish reports, because of our geographical position, would be of great offensive value to an enemy of Britain, they would benefit the British mainly in a defensive sense, and then only to limited extent (assuming that reports from the Six-Counties and from the North Atlantic would still be available to them). Thus although Britain could take grave exception to our broadcasting our reports to the world in wartime or otherwise making them available to her enemies, an enemy of Britain would not have a very strong case in objecting to a bilateral exchange between ourselves and Britain.
- The Minister for Industry and Commerce seeks the approval of the Government to inform the British Authorities of our agreement in principle to the proposal for a reciprocal exchange of meteorological reports in the event of war.
- The Ministers for External Affairs and Defence, who have been consulted, agree with the Minister’s proposal.1
Britain, through conferences held between NATO countries in recent years, has undoubtedly made special emergency arrangements for the exchange of weather data between the participating countries. The loss of Irish data would not drastically handicap British meteorologists, since it would lead only to a small area of ‘terra incognita’ surrounded by land and sea reporting stations. On the other hand, if Irish meteorologists were denied foreign weather reports, it would be virtually impossible to prepare satisfactory forecasts for home use, and it would be out of the question to forecast for international air flights. Accordingly, it would be very much in Ireland’s interest to exchange the small amount of Irish weather data for the much greater volume of foreign weather reports available to Britain.
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