Earth rotation and global change

Wilson, Clark R.

doi:10.1029/95rg00104

Cited by 15 publications

(3 citation statements)

References 67 publications

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“…As pointed out by Wilson (1995), LOD changes are inherently broad‐band power spectra processes. Moreover, it was shown by Kuehne et al .…”

Section: Discussionmentioning

confidence: 98%

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Detectability of deterministic non-linear processes in Earth rotation time-series-I. Embedding

Frède¹,

Mazzéga²

2002

Geophysical Journal International

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Summary Atmospheric and oceanic flows generate the main perturbations in the Earth’s rotation for periods shorter than about 100 days. Both their own dynamics and the Earth’s response being non‐linear, we expect to find non‐linear low‐dimensional deterministic signatures in filtered time‐series of Earth orientation parameters (EOP). Starting from daily observations of the length of day (LOD) and polar motion components (PMX, PMY) spanning more than 27 years, we apply non‐linear time‐series analysis techniques based on the embedding theory in order to determine the dimensional (this paper) and dynamic (Paper II) characteristics of the sought signal source. Estimates of the time delays required to embed the scalar data time‐series in a pseudo‐phase space E* are obtained from the average mutual information function. They are of 10 days for LOD, 15 days for PMX and 18 days for PMY. The dimension DE* of the embedding space E* then has to be determined to unfold the expected source attractor. We try two independent determinations, based on the percentage of global false neighbours and on the correlation integrals. We obtain embedding dimensions between 5 and 7 for the three EOP time‐series. The robustness of the results with regard to various data contaminations and series degradations is checked throughout. Finally, 3‐D projections of delayed coordinate data vectors are drawn. They are clearly different from stochastic power‐law noise and seem to issue from a smooth dynamical system whose dynamical characteristics are investigated in Paper II.

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“…As pointed out by Wilson (1995), LOD changes are inherently broad‐band power spectra processes. Moreover, it was shown by Kuehne et al .…”

Section: Discussionmentioning

confidence: 98%

“…As pointed out by Wilson (1995), LOD changes are inherently broad-band power spectra processes. Moreover, it was shown by Kuehne et al (1993) that the non-seasonal polar motion in response to atmospheric excitations (down to about 24 cycles yr À1 ) is non-stationary.…”

Section: Discussionmentioning

confidence: 99%

Detectability of deterministic non-linear processes in Earth rotation time-series-I. Embedding

Frède¹,

Mazzéga²

2002

Geophysical Journal International

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“…A review of relevant results can be found in Wahr (1988), Hide & Dickey (1991). Rosen (1993), Wilson (1995) and references therein. For our purposes, a summary of findings pertaining to scales from several days to seasons will suffice.…”

Section: Introductionmentioning

confidence: 99%

Oceanic excitation of daily to seasonal signals in Earth rotation: results from a constant-density numerical model

Ponte¹

1997

Geophysical Journal International

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S U M M A R YVelocity and mass fields from a constant-density, near-global ocean model, driven with observed twice-daily surface wind stresses and atmospheric pressures for the period October 1992-September 1993, are used to calculate oceanic excitation functions for the length of day (LOD) and for polar motion (PM), and results are analysed as a function of the frequency band. Variable currents and mass redistributions are both important in determining oceanic excitation functions. For bands with periods longer than one month, wind-driven variability is the primary cause of oceanic excitation signals. At higher frequency bands, larger deviations from the inverted barometer response occur, and pressure-driven signals contribute more significantly to the variance in the excitation functions. Oceanic LOD excitation is generally small compared to that of the atmosphere, except for the 2-10 day band. At these scales, adding oceanic to atmospheric excitation series does not lead to better agreement with the observed LOD, although this result may be related to data quality issues. With regard to the excitation of PM, the ocean is in general as important as the atmosphere at most time scales. Combined oceanic and atmospheric excitation series compare visibly better with geodetic series than do atmospheric series alone, pointing to the ocean as a source of measurable signals in PM.

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Excitation of non-atmospheric polar motion by the migration of the Pacific Warm Pool

Zhou¹,

Yan²,

Ding³

et al. 2004

Journal of Geodesy

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Earth rotation and global change

Cited by 15 publications

References 67 publications

Detectability of deterministic non-linear processes in Earth rotation time-series-I. Embedding

Detectability of deterministic non-linear processes in Earth rotation time-series-I. Embedding

Oceanic excitation of daily to seasonal signals in Earth rotation: results from a constant-density numerical model

Excitation of non-atmospheric polar motion by the migration of the Pacific Warm Pool

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