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| Titel |
Non-linear motions of VLBI stations with interannual and decadal periods and their connection with ENSO and sunspot cycles |
| VerfasserIn |
Yavor Chapanov, Harald Schuh, Robert Weber, Johannes Böhm |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037316
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| Zusammenfassung |
| The individual solutions for VLBI station coordinates provide time series of site
displacements with high accuracy for a time interval of more than 25 years for some stations.
These time series contain wide-spectrum signals from various local and global sources as
well as some systematic errors and uncertainties of the used mathematical models. A part of
the interannual and decadal natural signals in Earth surface systems can be related to the well
known El-Niño/Southern Oscillation (ENSO) and to decadal cycles of the solar activity due
to solar-terrestrial influences and the interconnection between the climatic and weather
variations, atmosphere and ocean conditions, hydrological and underground water cycles
and others. The interannual and decadal signals in VLBI site displacements are
investigated using the VLBI solution from Paris Observatory IVS Analysis Center
(OPAR). The variations of the smoothed time series of several VLBI sites (East,
North and Up directions) are compared with the corresponding variations of the
ENSO Index and Wolf sunspot numbers. The 22-year solar magnetic cycles are
represented by extended time series, determined by sign alternation of the even
11-year cycles of the Wolf numbers. The interconnection between solar cycles and
site displacements is investigated by least-squares estimation of the oscillations
with periods of 10.5 and 21 years, which are the mean periods of the Schwabe and
Hale Sun cycles for the last 30 years. These oscillations of the VLBI sites have
amplitudes between 0.2 mm and 1.5 mm and part of them are with phases close
to the corresponding oscillations of the sunspot indices. The spectrum of the site
displacements contains various signals with frequencies which can also be seen in the
ENSO frequency band with periods between 2 and 5 years. All time series of station
coordinates variations show correlation with the ENSO Index for some time intervals. |
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