Excitations of Seasonal Polar Motions Derived from Satellite Gravimetry and General Circulation Models: Comparisons of Harmonic and Inharmonic Analyses
Due to the conservation of global angular momentum, polar motion (PM) is dominated by global mass redistributions and relative motions in the atmosphere, oceans and land water at seasonal time scales. Thus, accurately measured PM data can be used to validate the general circulation models (GCMs) for...
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| Format: | Article |
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MDPI AG
2022-07-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/14/15/3567 |
| _version_ | 1797412506577141760 |
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| author | Haibo Liu Yan Zhou Jim Ray Jiesi Luo |
| author_facet | Haibo Liu Yan Zhou Jim Ray Jiesi Luo |
| author_sort | Haibo Liu |
| collection | DOAJ |
| description | Due to the conservation of global angular momentum, polar motion (PM) is dominated by global mass redistributions and relative motions in the atmosphere, oceans and land water at seasonal time scales. Thus, accurately measured PM data can be used to validate the general circulation models (GCMs) for the atmosphere, oceans and land water. This study aims to analyze geophysical excitations and observed excitations obtained from PM observations from both the harmonic and wavelet analysis perspectives, in order to refine our understanding of the geophysical excitation of PM. The geophysical excitations are derived from two sets of GCMs and a monthly gravity model combining satellite gravity data and some GCM outputs using the PM theory for an Earth model with frequency-dependent responses, while the observed excitation is obtained from the PM data using the frequency-domain Liouville’s equation. Our results show that wavelet analysis can reveal the time-varying nature of all excitations and identify when changes happen and how strong they are, while harmonic analysis can only show the average amplitudes and phases. In particular, the monthly gravity model can correct the mismodeled GCM outputs, while the Earth’s frequency-dependent responses provide us with a better understanding of atmosphere–ocean–land water–solid Earth interactions. |
| first_indexed | 2024-03-09T05:03:10Z |
| format | Article |
| id | doaj.art-dccf342e1dc741f7bb78d9f22c648d7c |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-09T05:03:10Z |
| publishDate | 2022-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-dccf342e1dc741f7bb78d9f22c648d7c2023-12-03T12:57:50ZengMDPI AGRemote Sensing2072-42922022-07-011415356710.3390/rs14153567Excitations of Seasonal Polar Motions Derived from Satellite Gravimetry and General Circulation Models: Comparisons of Harmonic and Inharmonic AnalysesHaibo Liu0Yan Zhou1Jim Ray2Jiesi Luo3Institute of Seismology, CEA, Wuhan 430071, ChinaInstitute of Seismology, CEA, Wuhan 430071, ChinaNational Oceanic and Atmospheric Administration, Silver Spring, MD 20910, USAKey Laboratory of Geospace Environment and Geodesy, School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, ChinaDue to the conservation of global angular momentum, polar motion (PM) is dominated by global mass redistributions and relative motions in the atmosphere, oceans and land water at seasonal time scales. Thus, accurately measured PM data can be used to validate the general circulation models (GCMs) for the atmosphere, oceans and land water. This study aims to analyze geophysical excitations and observed excitations obtained from PM observations from both the harmonic and wavelet analysis perspectives, in order to refine our understanding of the geophysical excitation of PM. The geophysical excitations are derived from two sets of GCMs and a monthly gravity model combining satellite gravity data and some GCM outputs using the PM theory for an Earth model with frequency-dependent responses, while the observed excitation is obtained from the PM data using the frequency-domain Liouville’s equation. Our results show that wavelet analysis can reveal the time-varying nature of all excitations and identify when changes happen and how strong they are, while harmonic analysis can only show the average amplitudes and phases. In particular, the monthly gravity model can correct the mismodeled GCM outputs, while the Earth’s frequency-dependent responses provide us with a better understanding of atmosphere–ocean–land water–solid Earth interactions.https://www.mdpi.com/2072-4292/14/15/3567Earth Orientation Parameterssatellite gravimetrytime-variable gravityfrequency-dependent responsesharmonic analysiswavelet analysis |
| spellingShingle | Haibo Liu Yan Zhou Jim Ray Jiesi Luo Excitations of Seasonal Polar Motions Derived from Satellite Gravimetry and General Circulation Models: Comparisons of Harmonic and Inharmonic Analyses Remote Sensing Earth Orientation Parameters satellite gravimetry time-variable gravity frequency-dependent responses harmonic analysis wavelet analysis |
| title | Excitations of Seasonal Polar Motions Derived from Satellite Gravimetry and General Circulation Models: Comparisons of Harmonic and Inharmonic Analyses |
| title_full | Excitations of Seasonal Polar Motions Derived from Satellite Gravimetry and General Circulation Models: Comparisons of Harmonic and Inharmonic Analyses |
| title_fullStr | Excitations of Seasonal Polar Motions Derived from Satellite Gravimetry and General Circulation Models: Comparisons of Harmonic and Inharmonic Analyses |
| title_full_unstemmed | Excitations of Seasonal Polar Motions Derived from Satellite Gravimetry and General Circulation Models: Comparisons of Harmonic and Inharmonic Analyses |
| title_short | Excitations of Seasonal Polar Motions Derived from Satellite Gravimetry and General Circulation Models: Comparisons of Harmonic and Inharmonic Analyses |
| title_sort | excitations of seasonal polar motions derived from satellite gravimetry and general circulation models comparisons of harmonic and inharmonic analyses |
| topic | Earth Orientation Parameters satellite gravimetry time-variable gravity frequency-dependent responses harmonic analysis wavelet analysis |
| url | https://www.mdpi.com/2072-4292/14/15/3567 |
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