Acknowledgements
The following institutions providing measurements of the magnetic field for the Dcx server from the mentioned stations are gratefully acknowledged:
Geomagnetic observatory Alma-Ata, Institute of the Ionosphere, Almaty, Republic of Kazakhstan: Alma-Ata (AAA)
The USGS Geomagnetism Program, U.S: Stennis (BSL), Honolulu (HON), San Juan (SJG) and Tucson (TUC)
Geomagnetism Project, Geoscience Australia: Canberra (CNB) and Gingin (GNG)
South African National Space Agency (SANSA), South Africa: Hermanus (HER) and Hartebeesthoek (HBK)
Boǧaziçi University, Kandilli Observatory and Earthquake Research Institute: Iznik (IZN)
Japan Meteorological Agency, Kakioka Magnetic Observatory: Kakioka (KAK)
Institut de Physique du Globe de Paris (IPGP), France: Lanzhou (LZH), Mbour (MBO), Pamatai (PPT), and Tamanrasset (TAM)
Chinese Earthquake Administration (CEA), China: Lanzhou (LZH)
Institut de Recherche pour le Développement (IRD), France: Mbour (MBO)
Commissariat à l'Énergie Atomique (CEA), France: Pamatai (Papeete) (PPT)
Centre de Recherche en Astronomie Astrophysique et Géophysique (CRAAG), Algeria: Tamanrasset (TAM)
