Geomagnetic field declination: from decadal to centennial scales
Declination annual mean time series longer than 1 century provided by 24 geomagnetic observatories worldwide, together with 5 Western European reconstructed declination series over the last 4 centuries, have been analyzed in terms of the frequency constituents of the secular variation at inter-d...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2018-04-01
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| Series: | Solid Earth |
| Online Access: | https://www.solid-earth.net/9/491/2018/se-9-491-2018.pdf |
| _version_ | 1818179521380089856 |
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| author | V. Dobrica C. Demetrescu M. Mandea |
| author_facet | V. Dobrica C. Demetrescu M. Mandea |
| author_sort | V. Dobrica |
| collection | DOAJ |
| description | Declination annual mean time series longer than 1 century provided by 24
geomagnetic observatories worldwide, together with 5 Western European
reconstructed declination series over the last 4 centuries, have been
analyzed in terms of the frequency constituents of the secular variation at
inter-decadal and sub-centennial timescales of 20–35 and
70–90 years. Observatory and reconstructed time series have been processed
by several types of filtering, namely Hodrick–Prescott, running averages, and
Butterworth. The Hodrick–Prescott filtering allows us to separate a
quasi-oscillation at a decadal timescale, which is assumed to be related to external variations and called the <q>11-year constituent</q>, from a long-term trend. The latter has been decomposed into two other oscillations called
<q>inter-decadal</q> and <q>sub-centennial</q> constituents by applying a
Butterworth filtering with cutoffs at 30 and 73 years, respectively. The
analysis shows that the generally accepted geomagnetic jerks occur around
extrema in the time derivative of the trend and coincide with extrema in the
time derivative of the 11-year constituent. The sub-centennial constituent is
traced back to 1600 in the five 400-year-long time series and seems to be a
major constituent of the secular variation, geomagnetic jerks included. |
| first_indexed | 2024-12-11T21:05:12Z |
| format | Article |
| id | doaj.art-41a2225ff70a40cb9cec1ddb1039e7be |
| institution | Directory Open Access Journal |
| issn | 1869-9510 1869-9529 |
| language | English |
| last_indexed | 2024-12-11T21:05:12Z |
| publishDate | 2018-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Solid Earth |
| spelling | doaj.art-41a2225ff70a40cb9cec1ddb1039e7be2022-12-22T00:50:52ZengCopernicus PublicationsSolid Earth1869-95101869-95292018-04-01949150310.5194/se-9-491-2018Geomagnetic field declination: from decadal to centennial scalesV. Dobrica0C. Demetrescu1M. Mandea2Institute of Geodynamics, Romanian Academy, Bucharest, RomaniaInstitute of Geodynamics, Romanian Academy, Bucharest, RomaniaCentre National d'Etudes Spatiales, Paris, FranceDeclination annual mean time series longer than 1 century provided by 24 geomagnetic observatories worldwide, together with 5 Western European reconstructed declination series over the last 4 centuries, have been analyzed in terms of the frequency constituents of the secular variation at inter-decadal and sub-centennial timescales of 20–35 and 70–90 years. Observatory and reconstructed time series have been processed by several types of filtering, namely Hodrick–Prescott, running averages, and Butterworth. The Hodrick–Prescott filtering allows us to separate a quasi-oscillation at a decadal timescale, which is assumed to be related to external variations and called the <q>11-year constituent</q>, from a long-term trend. The latter has been decomposed into two other oscillations called <q>inter-decadal</q> and <q>sub-centennial</q> constituents by applying a Butterworth filtering with cutoffs at 30 and 73 years, respectively. The analysis shows that the generally accepted geomagnetic jerks occur around extrema in the time derivative of the trend and coincide with extrema in the time derivative of the 11-year constituent. The sub-centennial constituent is traced back to 1600 in the five 400-year-long time series and seems to be a major constituent of the secular variation, geomagnetic jerks included.https://www.solid-earth.net/9/491/2018/se-9-491-2018.pdf |
| spellingShingle | V. Dobrica C. Demetrescu M. Mandea Geomagnetic field declination: from decadal to centennial scales Solid Earth |
| title | Geomagnetic field declination: from decadal to centennial scales |
| title_full | Geomagnetic field declination: from decadal to centennial scales |
| title_fullStr | Geomagnetic field declination: from decadal to centennial scales |
| title_full_unstemmed | Geomagnetic field declination: from decadal to centennial scales |
| title_short | Geomagnetic field declination: from decadal to centennial scales |
| title_sort | geomagnetic field declination from decadal to centennial scales |
| url | https://www.solid-earth.net/9/491/2018/se-9-491-2018.pdf |
| work_keys_str_mv | AT vdobrica geomagneticfielddeclinationfromdecadaltocentennialscales AT cdemetrescu geomagneticfielddeclinationfromdecadaltocentennialscales AT mmandea geomagneticfielddeclinationfromdecadaltocentennialscales |