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| Titel |
Noise Reduction of 1sec Geomagnetic Observatory Data without Information Loss |
| VerfasserIn |
Heinz-Peter Brunke, Monika Korte, Rudolf Widmer-Schnidrig |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143777
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| Publikation (Nr.) |
 EGU/EGU2017-7530.pdf |
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| Zusammenfassung |
| Traditional fluxgate magnetometers used at geomagnetic observatories are optimized towards long-term stability.
Typically, such instruments can only resolve background geomagnetic field variations up to a frequency of approximately 0.04 Hz and are limited by instrumental self-noise above this frequency. However, recently the demand for low noise 1 Hz observatory data has increased. IAGA has defined a standard for definitive 1sec data. Induction coils have low noise at these high frequencies, but lack long-term stability.
We present a method to numerically combine the data from a three axis induction coil system with a typical low-drift observatory fluxgate magnetometer. The resulting data set has a reduced noise level above 0.04 Hz while maintaining the long term stability of the fluxgate magnetometer. Numerically we fit a spline to the fluxgate data. But in contrast to such a low pass filtering process, our method reduces the noise level at high frequencies without any loss of information.
In order to experimentally confirm our result, we compared it to a very low noise scalar magnetometer: an optically pumped potassium magnetometer. In the frequency band from [0.03Hz to 0.5Hz] we found an rms-noise reduction from 80pT for the unprocessed fluxgate data to about 25pT for the processed data.
We show how our method improves geomagnetic 1 sec observatory data for, e.g., the study of magnetospheric pulsations and EMIC waves. |
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