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When the Shift from Analogue to Digital Data Occurred: A Case in Geomagnetic Data Services

Toshihiko IyemoriA Blog post by Toshihiko Iyemori (WDS Scientific Committee Member)

The World Data Centre for Geomagnetism, Kyoto (WDS Regular Member) has been collecting worldwide geomagnetic observation data under the ICSU World Data Centre (WDC) system/World Data System since 1957, collaborating with other WDCs for Geomagnetism in the United States (World Data Service for Geophysics), Russia (WDC - Solar-Terrestrial Physics, Moscow), the United Kingdom (WDC - Geomagnetism, Edinburgh), Denmark (WDC - Geomagnetism, Copenhagen), and India (WDC - Geomagnetism, Mumbai).

Figure 1 shows the number of observatories from which we keep data in analogue and digital forms.

Figure 1.

Optical recording on photo paper was originally used for most analogue recording.The digital recording of the data observed by modern electronic magnetometers started to increase from around 1980, and in 1992, finally overtook analogue recording. In 2000, the number of analogue stations had decreased to less than 10% of the total, and now all data are provided in digital form. In mid-1990s, the Internet and World Wide Web became popular, with WDC - Geomagnetism, Kyoto starting its web service in 1995.

The WDCs for Geomagnetism have been exchanging among themselves the data collected at each data centre for 60 years. During the analogue data era, it took money and manpower to collect data from distant observatories and copy them onto microfilms; and the big data centres such as WDC-A in Boulder (now World Data Service for Geophysics) or WDC-B in Moscow (now WDC - Solar-Terrestrial Physics, Moscow) mainly collected the data and distributed them to the other smaller data centres. After shifting to the digital data and Internet era, the situation changed. Collecting data via the Internet is much easier than collecting photo papers from distant stations, and international collaboration is also much easier than before.

Nowadays, more than half of geomagnetic data are provided through an international consortium, INTERMAGNET (WDS Network Member). The transition from analogue to digital recording thus also changed the main player in the provision of geomagnetic data services.