Geomagnetic field, measurement techniques

Abstract

Here, we concentrate primarily, but not exclusively, on geomagnetic instruments and techniques used in a magnetic observatory settings or in a near-Earth magnetic observation. We have briefly described the basic instruments, their mode of operation, their relative and/ or absolute accuracy, and the related sources of error. Currently, the magnetometry is a mature discipline, so something equivalent to the invention of the proton magnetometer would not be achieved very soon. It is more likely that some instrumental advances will be made toward the aim to stabilize vector magnetometers. Advances will be made in power reduction, data storage, and telemetry with the goals of increased automation and cutting costs. The coming age of the automated absolute instruments makes it possible to consider once again the possibility of a true underwater observatory. The future needs of the scientific and commercial users will include ground-and space-based measurements. Increasing resolution and timing accuracy will be crucial. However, to achieve these requirements will demand more efforts from instrument makers and spacecraft designers. The Earth’s magnetic field will remain under observation with the ESA’s forthcoming Swarm mission (Friis-Christensen et al., 2009). Three satellites will be launched in 2011 and will measure the magnetic field and its variations far more accurately than ever before. However, a comprehensive separation and understanding of the internal and external processes contributing to the Earth’s magnetic fields is possible only by joint analysis of satellite and ground-based data, with all difficulties arising in combining such different datasets. Continuous space-borne and ground-based monitoring of the magnetic field aims to address such needs.