Higher frequency ground magnetic field data by merging fluxgate and induction coil magnetometers

Guanren Wang - British Geological Survey, United Kingdom; Ciaran Beggan - British Geological Survey, United Kingdom; llen Clarke - British Geological Survey, United Kingdom; Chris Turbitt - British Geological Survey, United Kingdom

Session: Space Weather Instrumentation

Abstract

Digital magnetic observatories have traditionally aimed at the production of one-minute values, which generate various other outputs/indices used in space weather research and operational models. Whilst the need for these remains, measurements with a higher cadence are also needed in space weather.

Fluxgate magnetometers are widely used at observatories and variometer stations, where their long-term stability is a strength for measuring the spectrum of signals ranging from the Earth’s core field through to variations caused by ionospheric and lower frequency magnetospheric signals. However, they have an inherent instrumental noise floor, large enough to “mask” ambient natural signals of interest in the 0.1-10Hz frequency band.

Induction coil magnetometers are optimised to capture signals at higher-frequencies (0.1-100 Hz) with minimal instrument noise, although stability over a few hours is poor. They are however, capable of capturing the spectral range of signals from the ionosphere and magnetosphere/plasmasphere.

In this research we merge measurements from an induction coil and a fluxgate magnetometer, sited at Eskdalemuir Observatory, to produce "improved" time-series with frequencies 0.1-1Hz for the horizontal components of the magnetic field. The method and results are presented and the potential usage of such unique data sets in space weather discussed.