Detection of a New Large Free Core Nutation Phase Jump

Malkin, Zinovy; Belda, Santiago; Modiri, Sadegh

doi:10.3390/s22165960

Cited by 5 publications

(8 citation statements)

References 27 publications

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“…For a better representation of the FCN phase variations, the linear trend corresponding to the FCN frequency was removed from the FCN phase seb https://ivscc.gsfc.nasa.gov/products-data/product-tables/bkgproducts-eops.html ries. The results of the previous analysis [18] are also shown in these plots. Note that the IVS EOP series [18] ended in February 2022 (epoch 2022.…”

Section: Free Core Nutationmentioning

confidence: 87%

“…Like CW, the FCN is an oscillation with highly variable amplitude and phase that was investigated in many studies [12][13][14][15][16][17] and papers cited therein. In a recent paper [18] , a new minimum of the FCN amplitude and simultaneous large jump in the FCN phase was preliminary detected at the epoch around 2022.…”

Section: Introductionmentioning

confidence: 93%

“…The FCN amplitude and phase variations were studied using the ZM3 FCN model in the same way as it was done [18] . First, the ZM2 celestial pole offset (CPO) model was constructed by the Gaussian smoothing and interpolation at daily intervals of the combined EOP series maintained by the International VLBI Service for Geodesy and Astron-omy b (IVS).…”

Section: Free Core Nutationmentioning

confidence: 99%

“…It should be noted that the CW and FCN amplitude and phase variations [4,18] were obtained from analysis of the series of Earth orientation parameters (EOP) ended near the epochs of the investigated minima of the amplitude and phase jumps. Besides, both series used in these works are smoothed, the CW series to a lesser extent, and the FCN series to a larger extent.…”

Section: Introductionmentioning

confidence: 99%

“…Under these circumstances, today's behavior of the CW and FCN could not be accurately predicted when these papers were published. Therefore, it is very desirable to revise the results [4,18] using the latest available observations, which is the primary goal of this study.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Revisiting Recent Amplitude and Phase Variations of the Chandler Wobble and Free Core Nutation

Malkin

2023

eps

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The paper is devoted to the analysis of two components of the Earth’s rotation, Chandler wobble (CW) and free core nutation (FCN). They are oscillations with near-constant periods but variable amplitude and phase. The variations of the amplitude and phase of the CW and FCN have already been considered in the literature, and both showed similar behavior such as a recent significant decrease of the amplitude and large phase change. However, the CW and FCN amplitude and phase variations are, to a large extent, predicted for the current epochs, and their today’s variations need regular updates with obtaining new observations. In this work, the CW and FCN parameters have been re-computed using the latest data and compared with the data published earlier. It was found that the currently obtained amplitude and phase variations generally agreed with the data published earlier. The main difference is that the epochs of the current minimum of amplitude and phase jump or both CW and FCN happened somewhat later than was predicted in previous publications. The delay is about two years for the CW relative to the prediction made in 2010 and about one year for the FCN with respect to the prediction made in 2022.

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Section: Free Core Nutationmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 93%

Section: Free Core Nutationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Revisiting Recent Amplitude and Phase Variations of the Chandler Wobble and Free Core Nutation

Malkin

2023

eps

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EOP Prediction Based on Multi and Single Technique Space Geodetic Solution

Modiri,

Thaller,

Belda

et al. 2024

International Association of Geodesy Symposia

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Real-time Earth Orientation Parameters (EOP) are crucial in various space geodetic applications, from satellite navigation to weather forecasting. This study introduces a refined prediction package leveraging diverse EOP series from the Federal Agency of Cartography and Geodesy (BKG), including rapid and final series, Satellite Laser Ranging (SLR) series, and International Earth Rotation and Reference Systems Service (IERS) C04. Our approach yields substantial improvements in EOP prediction accuracy. Results highlight superior performance in critical parameters such as Polar Motion, (UT1-UTC) dUT1, and Length of Day (LOD) predictions. Notably, our predictions surpass benchmarks from the Second EOP Prediction Comparison Campaign (2nd EOP-PCC)” organized by International Association of Geodesy (IAG) and IERS, showcasing the effectiveness of our methodology. Additionally, BKG’s Rapid EOP stands out with remarkable accuracy, featuring a shorter latency of 1 to 2 days. This study contributes to our understanding of Earth’s rotational dynamics. It provides practical advancements in real-time EOP predictions, demonstrating the potential impact on a wide range of scientific and operational applications.

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Revisiting the Excitation of Free Core Nutation

Kiani Shahvandi,

Schindelegger,

Börger

et al. 2024

JGR Solid Earth

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Earth possesses a Poincaré mode called Free Core Nutation (FCN) due to the misalignment of the rotation axes of the mantle and fluid outer core. FCN is the primary signal in the observations of Celestial Pole Offsets (CPO) and maintained by geophysical mechanisms that are yet to be understood. Earlier studies suggested an origin in Atmospheric Angular Momentum (AAM)—and to a lesser degree Oceanic Angular Momentum (OAM)—but discrepancies between these geophysical excitations and the geodetic (CPO‐based) excitation were too large to reach definite conclusions. Here we use newly calculated, 3‐hourly AAM and OAM series for the 1994–2022 period, in conjunction with the latest CPO series from the International Earth Rotation and Reference Systems Service (IERS 20 C04 series), to demonstrate a markedly lower power ratio (4.6) of geophysical over geodetic excitation at the FCN frequency compared to previous works (ratio 10). Among all excitation sources, the AAM pressure term exhibits the highest coherence (0.56) and correlation (0.48) with the geodetic excitation, whereas the coherence with OAM is smaller by a factor of 3. Similar analyses using existing angular momentum series give comparable, albeit smaller coherence and correlation results. We attribute the relevant AAM pressure term signal to Northern Hemispheric landmasses and further show consistent temporal variations in the amplitude of geophysical and geodetic excitations around the FCN band. Our results thus corroborate evidence for large‐scale atmospheric mass redistribution to be the main cause of continuous FCN excitation.

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Detection of a New Large Free Core Nutation Phase Jump

Cited by 5 publications

References 27 publications

Revisiting Recent Amplitude and Phase Variations of the Chandler Wobble and Free Core Nutation

Revisiting Recent Amplitude and Phase Variations of the Chandler Wobble and Free Core Nutation

EOP Prediction Based on Multi and Single Technique Space Geodetic Solution

Revisiting the Excitation of Free Core Nutation

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