Acquisition of the Scandinavian IMS Magnetometer Array Data and Studies of Geomagnetic Rapid Variations

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During the IMS (International Magnetospheric Study) period (1977-1979) high time resolution geomagnetic observations were conducted by two magnetometer networks, North American Magnetometer Network (NAMN) and Scandinavian Magnetometer Array (SMA). While the data from NAMN have been open to the public through the World Data Center (WDC)-A for STP, the data of SMA had been used only within a research group of University of Munster, which took responsibility for the operation of SMA. The WDC-C2 for Geomagnetism, Kyoto University, negotiated about release of the data to the public and a set of th back-up film was transferred to the Center in 1989. The purpose of this research project was to make arrangements for the data release and to make analyses of geomagnetic rapid variations by using the data.The original back-up data were recorded on 35mm cinema film separately rolled in 42 large reels of 40cm diameter. Film length of one continuous recording is approximately 50 meters, which can not be accommodated in a normal smaller reel (9.2cm diameter, 100 feet roll) for usual film reader-printers. Further, it is desirable not to use the original film for daily analyses or data services because this is the only one set of back-up data in the world. Then we decided to copy the original back-up film into special thin film so that 50m of the data can be accommodated in a normal reel.In the first year of this project the whole data on the large reels were copied into 567 small reels of film. In the second year the names of the stations and data periods were labeled on each reel and reference lists for data analysis were prepared. Then the data were analyzed for 2 geomagnetic sudden commencement events and 2 geomagnetic pulsation events by combining the data from NAMN. It was shown that the data can be used effectively for studies of both local fine structure and longitudinal variation of geomagnetic rapid variations.