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Solar Activity as a Danger to Ground-based Technological Systems
Published in Olga Sokolova, Nikolay Korovkin, Masashi Hayakawa, Geomagnetic Disturbances Impacts on Power Systems, 2021
Olga Sokolova, Nikolay Korovkin, Masashi Hayakawa
The International Real-Time Magnetic Observatory Network (INTERMAGNET) was founded in late 1980s in order to prompt the operation of magnetic observatories according to modern standards. INTERMAGNET institutes have cooperatively developed infrastructure for data exchange and management as well as methods for data processing and checking [101]. To reliably produce a long-period geomagnetic time series, an observatory must operate under carefully controlled conditions [102]. It was essential to convince the international observatory community that adopting modern technologies and data processing would not comprise the data quality required for secular variation studies. This has been clearly demonstrated. As a result about half of world's observatories were INTERMAGNET members in 2001 [103]. Currently, INTERMAGNET consists of ca. 170 observatories operated by government, academic and commercial institutes. An interface between individual observatories and data users is real-time data collection centers, designated Geomagnetic Information Nodes (GINs). They are connected to the INTERMAGNET observatories by satellite, computer and telephone networks. There are GINs in North America (USGS, Golden and GSC, Ottawa), Europe (BGS, Edinburgh and IPGP, Paris) and Japan (Kyoto and Hiraiso). The Kyoto GIN is run by the World Data Center for Geomagnetism at Kyoto University. The GIN in Hiraiso is operated by the Hiraiso Solar Terrestrial Research Center, Communications Research Laboratory. The picture of GINs and corresponding satellites is presented in Fig. 2.17.
Advances in geodynamo modelling
Published in Geophysical & Astrophysical Fluid Dynamics, 2019
Johannes Wicht, Sabrina Sanchez
Geomagnetic observations from magnetic observatories (INTERMAGNET1) and satellite missions (e.g. Swarm, CHAMP, Ørsted) measure the field at different altitudes. The signal is a convolution of several sources. In addition to the Earth's core dynamo, induced and remnant crustal magnetisation, ionospheric and magnetospheric currents, and currents induced in the ocean also contribute (Hulot et al.2015). Internal and external fields can be separated in the spherical harmonic domain based on the different functional form of the respective potential fields. However, since the internal field remains an entanglement of crustal and core signal, core field models are restricted to the range where the crustal contribution remains subdominant. Notable core field models are the historical gufm1 (Jackson et al.2000), the more observatory-based COV-OBS (Gillet et al.2013), and the more satellite-based CHAOS (Finlay et al.2016).