Monitoring climate variability with broadband magnetometers
Thomson, Alan; Flower, Simon. 2007 Monitoring climate variability with broadband magnetometers. [Poster] In: BGS/NERC Climate Change Workshop, BGS Keyworth, Nottingham, 18 January 2007. (Unpublished)Before downloading, please read NORA policies.
The ionosphere acts as a natural 'upper' electrical conducting surface that, together with the conducting Earth below, forms a waveguide within which electromagnetic resonances can be established. Known as Schumann resonances, the amplitude of both the fundamental (~7.8Hz) and harmonics are influenced by upper tropospheric water vapour content and by global temperature. Resonances are of short duration (a few seconds) and are triggered by lightning strikes anywhere on the globe (particularly from equatorial electrical storm activity). The frequency of lightning flashes is therefore a simple measure of changing atmospheric conditions on many time scales. Schumann resonances are, however, only one atmospheric electromagnetic phenomenon. Other more exotic phenomena (only recently discovered) include 'Sprites', which connect tropospheric storm systems upwards to the ionosphere, the upper Atmosphere and to solar-driven 'space weather' and ‘solar climatology’. Magnetometers have been used by a number of researchers to monitor variations in the atmospheric electrical circuit, although observations have typically been made only on short campaign bases. The value of a magnetometer is that one instrument in one location can be used to derive information on the global atmospheric electrical circuit and on changing climatic conditions (particularly global equatorial temperature and tropospheric water vapour changes). Magnetic measurements are also an independent monitor of long-term changes in atmospheric conditions. Because of the scientific and public interest in climate change and the BGS commitment to long term monitoring, the Seismology and Geomagnetism Programme has been testing an induction coil magnetometer system, at Eskdalemuir magnetic observatory (Scottish Borders). The induction coil has been in continuous use since Autumn 2006 and we are currently testing and accumulating data over the long term in support of climate monitoring. In comparison with the requirements on standard observatory geomagnetic measurements for monitoring deep Earth processes, the frequency range of interest (>1Hz) is relatively high. Therefore, in addition to monitoring climate modulated data, we are also learning about this type of magnetometer and are gaining valuable technical experience which may enhance future observatory operations and scientific data products. In this poster we discuss aspects of atmospheric electrical science and climate variability, through examples from the published literature, and we describe the BGS installation at Eskdalemuir.
|Item Type:||Conference or Workshop Item (Poster)|
|Programmes:||BGS Programmes > Seismology and Geomagnetism|
|NORA Subject Terms:||Earth Sciences
Meteorology and Climatology
|Date made live:||01 Nov 2012 16:36|
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