Identifying the causes of the vertical component geomagnetic field anomaly at Eskdalemuir, Scotland

Wang, Guanren ORCID: https://orcid.org/0000-0001-9563-8864; Huebert, Juliane ORCID: https://orcid.org/0000-0003-0526-5609; Kathryn, Whaler ORCID: https://orcid.org/0000-0002-7386-223X. 2022 Identifying the causes of the vertical component geomagnetic field anomaly at Eskdalemuir, Scotland. [Lecture] In: EMIW 2022, Çeşme, Türkiye, 25 Sept 2022. (Unpublished)

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Abstract/Summary

Magnetic field observations in the Scottish Southern Uplands reveal a dampened amplitude in the vertical component variations at Eskdalemuir when compared with the horizontal components for periods less than an hour. This relationship is not observed elsewhere. A high conductivity feature beneath Eskdalemuir has been the focal point of past literature to account for this local anomaly. However, the impact of solar activities on the external field variations at Eskdalemuir has yet to be investigated as a possible cause. This is an important factor to consider because it is assumed that large current systems are uniform at mid-latitude for geomagnetic depth sounding techniques to be applied. When this assumption is violated, the vertical magnetic field is most sensitive to the presence of non-uniform contributions. In this study we aim to characterise the space-weather driven external field contributions at different timescales to the measured vertical field component, using long time series of modern data recorded at the Eskdalemuir magnetic observatory. Vertical magnetic transfer functions (tippers) are estimated using three-month datasets at one-minute and one-second cadences between 2003 and 2019 in order to examine their temporal variations due to the impact from source effects. Our results show that at Eskdalemuir, there are significant variations in the tipper estimates for periods above 1000 seconds between summer and winter months for the same year, especially in the Real Tx component. These findings have implications for data collected during other field campaigns with shorter recording times. Long time series of one-second and minute-mean magnetic field data recorded BGS’ Eskdalemuir geomagnetic observatory are used to analyse and correct for space-weather-driven contributions to observations in southern Scotland. These observations were recorded as part of the Space Weather Instrumentation, Measurement, Modelling and Risk Activities in Ground Effects (SAGE). A key objective of SAGE is to use these long period magnetotelluric data, sampled at 1 second over 4 weeks, to produce a new and accurate 3D ground electric field model of the UK to better understand the impact of geomagnetic induced currents during severe space weather storms.

Item Type:	Publication - Conference Item (Lecture)
Programmes:	BGS Programmes > Seismology and Geomagnetism
NORA Subject Terms:	Earth Sciences Space Sciences
Date made live:	30 Apr 2025 09:30 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/539358

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