Atmospheric and oceanic contributions to Chandler wobble excitation determined by wavelet filtering

Seitz, Florian; Schmidt, Michaël

doi:10.1029/2005jb003826

Cited by 31 publications

(31 citation statements)

References 29 publications

(53 reference statements)

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“…DyMEG allows for the consideration and superposition of various effects which makes the model an ideal tool for the forward simulation and analysis of ERP. It has been shown in several studies that the results of DyMEG agree well with observed ERP on timescales from days to several years [e.g., Seitz and Schmidt, 2005].…”

Section: Dynamic Earth System Model Dymegsupporting

confidence: 65%

“…The annual oscillation is predominantly induced by geophysical processes in the Earth system. The Chandler oscillation is a free rotational mode of the Earth, originating from the misalignment of the polar [Seitz and Schmidt, 2005] of observations provided by the IERS in its C01 and C04 series [Dick and Richter, 2009]. While the annual signal is rather uniform, the Chandler oscillation features strong amplitude variations.…”

Section: Theorymentioning

confidence: 99%

“…Due to energy dissipation in the Earth system, mainly caused by the anelasticity of the Earth's mantle, the Chandler oscillation is damped. Angular momentum variations within the coupled atmosphere-ocean system excite this resonance oscillation and thus counteract its damping [Gross, 2000;Seitz and Schmidt, 2005].…”

Section: Theorymentioning

confidence: 99%

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Determination of the Earth's pole tide Love number k₂ from observations of polar motion using an adaptive Kalman filter approach

2012

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[1] The geophysical interpretation of observed time series of Earth rotation parameters (ERP) is commonly based on numerical models that describe and balance variations of angular momentum in various subsystems of the Earth. Naturally, models are dependent on geometrical, rheological and physical parameters. Many of these are weakly determined from other models or observations. In our study we present an adaptive Kalman filter approach for the improvement of parameters of the dynamic Earth system model DyMEG which acts as a simulator of ERP. In particular we focus on the improvement of the pole tide Love number k 2 . In the frame of a sensitivity analysis k 2 has been identified as one of the most crucial parameters of DyMEG since it directly influences the modeled Chandler oscillation. At the same time k 2 is one of the most uncertain parameters in the model. Our simulations with DyMEG cover a period of 60 years after which a steady state of k 2 is reached. The estimate for k 2 , accounting for the anelastic response of the Earth's mantle and the ocean, is 0.3531 + 0.0030i. We demonstrate that the application of the improved parameter k 2 in DyMEG leads to significantly better results for polar motion than the original value taken from the Conventions of the International Earth Rotation and Reference Systems Service (IERS).

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Section: Dynamic Earth System Model Dymegsupporting

confidence: 65%

Section: Theorymentioning

confidence: 99%

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Determination of the Earth's pole tide Love number k₂ from observations of polar motion using an adaptive Kalman filter approach

2012

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“…Following Aoyama et al (2003), atmospheric and ocean-bottom pressure and winds are comparable sources of excitation, intermittently playing a prominent role. Seitz & Schmidt (2005) conclude that the atmospheric and oceanic bottom pressure fluctuations are the prominent cause of the CW variability. They could account for some features in the band of 400-460 days by wavelet analysis: an amplitude increase between 1980 and 1990 and a decrease after 1993.…”

Section: Introductionmentioning

confidence: 99%

The Earth’s variable Chandler wobble

Bizouard

Remus

Lambert

et al. 2011

A&A

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Aims. We investigated the causes of the Earth's Chandler wobble variability over the past 60 years. Our approach is based on integrating of the atmospheric and oceanic angular momentum computed by global circulation models. We directly compared the result of the integration with the Earth's pole coordinate observed by precise astrometric, space, and geodetic techniques. This approach differs from the traditional approach in which the observed polar motion is transformed into a so-called geodetic excitation function, and compared afterwards with the angular momentum of the external geophysical fluid layers. Methods. In the time domain, we integrated the atmospheric angular momentum time series from the National Center for Environmental Prediction/National Center for Atmospheric Research Reanalysis project and the oceanic angular momentum data from the ECCO consortium. We extracted the Chandler wobble from this modeled polar motion by singular spectrum analysis, and compared it with the Chandler wobble extracted from the observed polar motion given by the International Earth Rotation and Reference Systems Service data. Results. We showed that the combination of the atmosphere and the oceans explains most of the observed Chandler wobble variations, and is consistent with results reported in the literature and obtained with the traditional approach. Our approach allows one to appreciate the separate contributions of the atmosphere and the oceans to the various bumps and valleys observed in the Chandler wobble. Though the atmosphere explains the Chandler wobble amplitude variations between 1949 and 1970, the reexcitation of the Chandler wobble that begins in the 1980s, after a minimum around 1970, and that reaches its maximum in the late 1990s is due to the oceans, while the atmospheric contribution remains stable within the same period.

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“…Some researchers have suggested that the CW is highly variable with respect to its amplitude (e.g., Carter, 1981Carter, , 1982Höpfner, 2003;Chen et al, 2009Chen et al, , 2013a, some have considered it to have double or multiple frequencies (e.g., Chao, 1983;Pan, 2012), and some have considered its frequency to be invariant (e.g., Okubo, 1982;Vicente and Wilson, 1997;Gross et al, 2003;Seitz and Schmidt, 2005). If the CW is frequency modulated as Carter (1981Carter ( , 1982 suggested, namely, the frequency is governed by the magnitude, it will create an infinite number of sidebands, arranged symmetrically about the carrier and spaced at integer multiples of the modulating frequency (Carter, 1981).…”

Section: Introductionmentioning

confidence: 99%

Search for the 531-day-period wobble signal in the polar motion based on EEMD

Ding

Shen

2015

Nonlin. Processes Geophys.

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Abstract. In this study, we use a nonlinear and nonstationary time series analysis method, the ensemble empirical mode decomposition method (EEMD), to analyze the polar motion (PM) time series (EOP C04 series from 1962 to 2013) to find a 531-day-period wobble (531 dW) signal. The 531 dW signal has been found in the early PM series (1962)(1963)(1964)(1965)(1966)(1967)(1968)(1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977), but cannot be found in the recent PM series (1978-2013) using conventional analysis approaches. By virtue of the demodulation feature of EEMD, the 531 dW can be confirmed to be present in PM based on the differences of the amplitudes and phases between different intrinsic mode functions. Results from three sub-series divided from the EOP C04 series show that the period of the 531 dW is subject to variations, in the range of 530.9-524 days, and its amplitude is also time-dependent (about 2-11 mas). Synthetic tests are carried out to explain why the 531 dW can only be observed in recent 30-year PM time series after using EEMD. The 531 dW is also detected in the two longest available superconducting gravimeter (SG) records, which further confirms the presence of the 531 dW. The confirmation of the 531 dW existence could be significant in establishing a more reasonable Earth rotation model and may effectively contribute to the prediction of the PM and its mechanism interpretation.

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Atmospheric and oceanic contributions to Chandler wobble excitation determined by wavelet filtering

Cited by 31 publications

References 29 publications

Determination of the Earth's pole tide Love number k₂ from observations of polar motion using an adaptive Kalman filter approach

Determination of the Earth's pole tide Love number k₂ from observations of polar motion using an adaptive Kalman filter approach

The Earth’s variable Chandler wobble

Search for the 531-day-period wobble signal in the polar motion based on EEMD

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Atmospheric and oceanic contributions to Chandler wobble excitation determined by wavelet filtering

Cited by 31 publications

References 29 publications

Determination of the Earth's pole tide Love number k2 from observations of polar motion using an adaptive Kalman filter approach

Determination of the Earth's pole tide Love number k2 from observations of polar motion using an adaptive Kalman filter approach

The Earth’s variable Chandler wobble

Search for the 531-day-period wobble signal in the polar motion based on EEMD

Contact Info

Product

Resources

About

Determination of the Earth's pole tide Love number k₂ from observations of polar motion using an adaptive Kalman filter approach

Determination of the Earth's pole tide Love number k₂ from observations of polar motion using an adaptive Kalman filter approach