German Weather Reporting Activities
- Weather reporting U-boats: January 1944 - May 1945.
Since Europe's weather may be forecast through knowledge of weather as it moves eastward across the Atlantic, Germany has, since the beginning of the war, shown a keen interest in the weather conditions in the North Atlantic. This data has been gained by them from two sources: U-boats on station patrol in a small area of the North Atlantic and meteorological stations set up in Greenland, Spitzbergen, and Franz Joseph Land. OP-20-G kept COMINCH informed of all activity.
Weather reports from U-boats prior to 31 December 1943 occurred in two circumstances: append to ENIGMA transmissions and in short weather cipher upon order. But beginning 31 December 1943 and continuing until the end of the war, weather reporting U-boats have been stationed in assigned areas of the North Atlantic, and the coverage has been complete except for a few days. The North Atlantic was divided into three parts: North, Central, and South. For the most part, three U-boats reported in the short weather cipher twice daily between 0000B-02008 and 10008-12008. No difficulties were encountered at first except for occasional interruption of radio communication from ionospheric storms, at which time the U-boats would transmit on a series other than their assigned circuit. In the early summer of 1944, however, an increasing fear of being D/F'd forced the Germans to change their methods of reporting. Fixed schedule for sending reports were abolished. U-boats were ordered to "transmit irregularly in order to make it difficult for enemy D/F service to gain knowledge of the return course," and no one was to "try to get through more than three times in succession." (1616/30 August) The DAN off-frequencies became popular with the weather U-boats in their attempt to escape detection.
Upon failure to receive these reports, Control issued emphatic messages on the importance of regular receipt of weather data. In May, the U-boats were told that: "Reports are of utmost importance for the entire conduct of the war - judgment as to air situation, invasion, etc." (1416/4) After the Allied landings in France in June, weather reports were
demanded with even more urgency. Additional measures were taken to insure the reception of these reports. All outbound Uboats were ordered to send short signal weather reports as passage reports, and, due to delay or absence of assigned boats, others destined for operational areas in American waters reported weather conditions while cruising through the weather reporting area.
In December 1944 weather reporting once more assumed special importance. On 2 December the U-boats were told that "weather reports are of the greatest importance for the war on land and in the air" (1934/2 November); "Importance and seriousness of task demands that all means be used to get messages through." (1822/3 December) The task contemplated was the German breakthrough in Belgium on 16 December, which owed much of its initial success to the skillful use of weather cover.
"Your recent weather reports contributed decisively to determining the beginning of our great offensive in the west on 16/12." (1930/19 December)
In August, and from November 1944 to February 1945, experiments were conducted in the Skaggerak with a new high speed transmitting procedure, "Kurrier," which could not be D/F'd. Presumably this new method was designed with weather transmission difficulties in mind, as reference to a "Kurierkurzwettertafel" (Kurier short weather table) appeared in traffic. However, other types of short signals are known to have been transmitted on "Kurier" during the trails.
Fifty-three U-boats were assigned as weather reporters, and five were sunk during or prior to their performance of these duties. Hossenfelder (U-342) was sunk by Iceland-based RAF aircraft on 17 April 1944 near 60°N - 30°W. HMS Vindex was sent after Wendt (U-1276) with instructions that included Wendt's area and routine times of transmitting. Wendt was sunk 6 May 1944 in 52°30'N - 28°27'W. Task Group 22.8, having been informed of the area in which a weather U-boat was operating, sank Loos (U-248) on 16 January 1945 in 47°43'N - 26°37'W. Findeisen (U-877) was sunk by HMCS Thomas on 27 December 1944 in 46°25'N - 36°36'W. Clausen (U-1226) was sunk between 23 and 31 October 1944 in the vicinity of 59°33'N - 20°24'W before reaching his weather reporting area.
- German meteorological activity in the Arctic, 1942-1945.
- Greenland meteorological stations.
The fact that Europe's weather originates in Greenland caused a desperate, continuous effort on the part of the Germans to establish and maintain a meteorological station on the east coast of that island from August 1942 to October 1944:
Holzauge - August 1942 to June 1943 Bassgeiger - September 1943 to June 1944 Edelweiss I - September 1944 (captured before landing) Edelweiss II - October 1944 (captured 3 days after landing)
Great precaution was practiced during the setting up of weather stations. Each Greenland expedition set sail from Norway in the early fall with a U-boat escort as far as the ice boundary, in order to reach a location "as far north as possible," and become frozen in soon afterward, thereby preventing, or at least delaying, discovery by patrol vessels, planes or sledge patrols. Once established, a station was considered safe for the winter, although its location could be detected through bearings on transmissions or through intercepted messages concerning the station on German naval Kootwijk circuit. The importance attached to maintaining stations in Greenland was evidenced by the decision to send the "Goldschmied" expedition, originally destined for Franz Josef Land, to Greenland as "Edelweiss II," one month after the capture of "Edelweiss I" by the USCGC Northland. For details of each expedition see the chart following section (c). A large amount of the information was made available by prisoners of war and captured documents.
- Jan Mayen HF/DF station.
In September 1943, the U.S. Army decided to discontinue its aerial reconnaissance of northeast Greenland due to "its doubtful value and winter storms." At that time there were indications that the Germans had established another weather station on the east coast of Greenland ("Bassgeiger") despite the destruction of the previous station in May - June 1943. As a high frequency radio direction finder station was the best means of detecting enemy activity in the Arctic, such a station was set up on Jan Mayen Island (71°01'N - 08°25'30"W) by
agreement with the Norwegians; it was commissioned 27 November 1843 and operated by the U.S. Coast guard. During the following month and a half, the equipment was checked and tested by taking bearings on known stations in the Arctic region. In October 1943 GC&CS had advised by dispatch of the call signs used by the Greenland station and its ship and also of the frequencies on which the German Arctic Met Circuit transmitted. This information enabled the station to operate immediately after the equipment was put into working order and saved time which might have been wasted searching for the stations.
On 18 January 1944 Jan Mayen picked up, for the first time, transmissions from "Bassgeiger," Coburg, and Control at Tromsoe, Norway, and took bearings on them, thus determining the location of the Greenland station and its expeditionary ship. Upon receipt of this data, air reconnaissance was planned and sledge patrols were informed of the station's existence. After several attempts were made to reach the station by land, a seven man sledge patrol finally attacked it 22 April 1944. Although the attack itself was not successful, it led to the eventual evacuation of the station in June 1944.
No German weather station operated on Greenland after "Bassgeiger" as both "Edelweiss" expeditions were captured before the stations were completed, but Jan Mayen kept track of "Haudegen's" transmissions from Sptizbergen.
Although traffic passed on the "Love" circuit (the circuit used by all Arctic weather stations) was intercepted by the Jan Mayan H/F D/F station, decryption was dependent upon repetition of the messages on the Kootwijk circuit (circuit "C") in ENIGMA because of the expeditions' use of one-time pads. In addition, OP-20-G was dependent upon the British for complete coverage of circuit C due to the inability of American stations to pick up all transmissions on Kootwijk frequencies. In the case of "Bassgeiger" from November 1943 until March 1944 Admiralty advised by dispatch of all developments regarding the station and its ship as they were reported to headquarters in Norway on circuit C. Information which was not signaled was forwarded in British ZIP's.
- Other Arctic meteorological stations.
While attempts were being made by the Germans to establish meteorological stations on Greenland, other stations
were reporting meteorological conditions on Spitzbergen and Franz Josef Land.
Spitzbergen: "Nussbaum" - 1942-1943 (captured by British) "Kreuzritter" - 1943-1944 (men returned because of illness) "Haudegen" - 1944-1945 Franz Josef Land: "Schatzgräber" - 1943-1944
From captured documents, it was revealed that at the time of sailing of the "Edelweiss I" expedition for Greenland in August 1944, plans were also underway to send "Haudegen" and "Goldschmied" expeditions to Spitzbergen and Franz Josef Land, respectfully. However, with the capture of "Edelweiss I" the "Goldschmied" party became "Edelweiss II" thereby apparently eliminating the possibility of any meteorological operations on Franz Josef Land in the near future. This impression was confirmed when Buchler (U-387) was ordered on 10 October to proceed to Alexandraland, the southwestern portion of Franz Josef Land, to take off the two weather transmitters which had been left there for the use of future expeditions.
"Haudegen" transmissions were not heard by Jan Mayen until the end of November 1944 and bearings indicated that the station was located on northwest Spitzbergen rather than on North East Land, the northeastern island of the group, as previously planned. Presumably the change in the location of the station came as a result of the failure of both "Edelweiss" expeditions to Greenland, since advance weather information from the western Arctic was much more valuable than that from the eastern Arctic. This station continued to operate until the end of the war.
GC&CS was immediately informed by dispatch of Jan Mayen's findings.
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