L. Zotov - Profile on Academia.edu (original) (raw)

Papers by L. Zotov

Earth's rotation, Russian national geodetic report

Lecture Notes in Electrical Engineering, 2012

The most important factor in getting accurate predictions of Earth orientation parameters (EOP) i... more The most important factor in getting accurate predictions of Earth orientation parameters (EOP) is choosing suitable input data. Also, we must choose a proper statistical model for the noise in these data. The weights of the data are determined on the basis of these models. Finally, we must determine suitable values of parameters in the computation of EOP predictions.

Different methods of geodetic excitation reconstruction from observations of the polar motion are... more Different methods of geodetic excitation reconstruction from observations of the polar motion are compared. Among them Wilson-Jeffreys filter, Tikhonov regularization, Panteleev corrective smoothing. Reconstruction of Chandler excitation is an inverse problem, aggravated by the strong annual oscillation, which is nearby in frequency band. Special attempts to filter annual oscillation out were undertaken, among them the harmonic model subtraction, Singular Spectrum Analysis (SSA) and Panteleev smoothing. Obtained results compared one with another and with geophysical excitations, such as atmospheric and oceanic angular momentum, El Nino event, solar and lunar tides. Amplitude and phase correlation analysis was performed. Phase change of the Chandler oscillation in the 30-th of the XX century found a partial explanation.

Gravity changes over Russian rivers basins from GRACE (Chapter 3)

Water Resources, 2017

Many-year variations of river runoff in the Selenga basin are analyzed along with precipitation, ... more Many-year variations of river runoff in the Selenga basin are analyzed along with precipitation, potential evapotranspiration, and basin water storages. Data of ground-based (1932-2015) and satellite observations, as well as the analysis of literature data suggest the presence of within-century cycles in the series of annual and minimum runoff. Compared with 1934-1975, the Selenga Basin shows a general tendency toward a decrease in the maximum (by 5-35%) and mean annual (up to 15%) runoff at an increase in the minimum runoff (by 30%), a decrease in the mean annual precipitation (by 12%), and an increase in potential evapotranspiration by 4% against the background of a decrease in evaporation because of lesser soil moisture content and an increase in moisture losses for infiltration because of permafrost degradation. The observed changes in water balance may have unfavorable environmental effects.

Astronomy Reports, 2015

Light curves of the eclipsing binary FL Lyr acquired by the Kepler space telescope are analyzed. ... more Light curves of the eclipsing binary FL Lyr acquired by the Kepler space telescope are analyzed. Eclipse timing measurements for FL Lyr testify to the presence of a third body in the system. Preliminary estimates of its mass and orbital period are 4M J and 7 yrs. The times of primary minimum in the light curve of FL Lyr during the operation of the Kepler mission are presented. 1 In other words, to perform timing of the minima of the FL Lyr light curve. 2 Expressed in fractions of the orbital semi-major axis of FL Lyr. 3 Expressed in fractions of the system's combined luminosity.

Achievements of the Earth orientation parameters prediction comparison campaign

Journal of Geodesy, 2010

Artificial Satellites, 2010

Dynamical Modeling and Excitation Reconstruction as Fundamental of Earth Rotation Prediction Thou... more Dynamical Modeling and Excitation Reconstruction as Fundamental of Earth Rotation Prediction Though pure mathematical approximations such as regression models and neural networks show good results in Earth rotation forecasting, dynamical modeling remains the only base for the physically meaningful prediction. That assumes the knowledge of cause-effect relationships and physical model of the rotating Earth. Excitation reconstruction from the observed Earth orientation parameters (EOP) is a crucial stage, needed for comparison with known causes, such as tidal forcing, atmospheric (AAM), oceanic (OAM) angular momentum changes, and uncovering unknown ones. We demonstrate different approaches, which can be used to avoid ill-conditionality and amplification of noises during the inversion. We present amplitude and phase studies of the model and reconstructed excitations of Chandler wobble. We found out, that modulation of Chandler excitation is synchronous with 18-yr tidal effects in the E...

Odessa Astronomical Publications, 2013

Singular Spectrum Analysis (SSA) of Global Mean Sea Level (GMSL) and Global Average Earth Tempera... more Singular Spectrum Analysis (SSA) of Global Mean Sea Level (GMSL) and Global Average Earth Temperature (HadCRUT4) data revealed presence of quasiperiodic components with periods of 60, 20 and 10 years in both time series. 60-year component of sea level is anticorrelated with long-periodic changes in temperature, while 10 and 20-year components are correlated. The question what can be the nature of these common oscillations is discussed.

Chandler Wobble and Lod Anomalyes in 2010-2020S

19th Annual Meeting of the Asia Oceania Geosciences Society

Journal of Geophysical Research: Solid Earth, 2022

• Admittance coefficients defining the Earth's rotational response to zonal tidal components are ... more • Admittance coefficients defining the Earth's rotational response to zonal tidal components are determined from the length of day changes. • This study applies the full hydro-atmospheric corrections to be removed from the LOD before estimating the admittances. • The dispersion between the estimated admittances and their frequency dependent modelled values between 7 and 35 days is reduced substantially.

The works that we carried out during the last ten years lead to significant progress in the knowl... more The works that we carried out during the last ten years lead to significant progress in the knowledge of the Chandler wobble (CW) of the Earth polar motion (PM). In Zotov and Bizouard (2012) we reconstructed the excitation of this resonant mode by using Panteleev’s corrective filtering. Now we are sure, that this filtering is a regularizing algorithm as far as its parameters are consistently selected with the uncertainty affecting the resonance parameters and the observations. The excitation demonstrated a quasi 20-year amplitude modulation. In the framework of the first order differential linear equation describing the polar motion, it is easy to show that this modulation accounts for the 40-year change of the CW amplitude as well as the splitting of the CW spectra. A simple model of the CW, composed of 80 and 40-year harmonics, accounts for the present minimum in Chandler wobble amplitude, like in 1930s, and also predicts that its amplitude will start to increase in the nearest fu...

Journal of Geodynamics, 2012

We derive the Chandler wobble excitation from the polar motion (PM) observations by using the Pan... more We derive the Chandler wobble excitation from the polar motion (PM) observations by using the Panteleev corrective filtering. The latter method is based on inversion of the Euler-Liouville equation, with additional filtering in the Chandler frequency band. The excitation reconstruction reveals amplitude changes different from the one observed in the Chandler wobble itself. Their main feature, well observable over the length of the day (LOD), is the presence of a 18.6-year amplitude modulation synchronous with the lunar orbital precession cycle and tidal effects. The filtering of oceanic and atmospheric excitation in the Chandler frequency band also reveals a coherent 18.6-year oceanic pattern. Most probably the ocean provide a channel for the tidal energy transfer.

Geoinformatics Research Papers, 2015

In this National Report are given major results of researches conducted by Russian geodesists in ... more In this National Report are given major results of researches conducted by Russian geodesists in 2011-2014 on the topics of the International Association of Geodesy (IAG) of the International Union of Geodesy and Geophysics (IUGG). This report is prepared by the Section of Geodesy of the National Geophysical Committee of Russia. In the report prepared for the XXVI General Assembly of IUGG (Czhech Republic, Prague, 22 June-2 July 2015), the results of principal researches in geodesy, geodynamics, gravimetry, in the studies of geodetic reference frame creation and development, Earth's shape and gravity field, Earth's rotation, geodetic theory, its application and some other directions are briefly described. For some objective reasons not all results obtained by Russian scientists on the problems of geodesy are included in the report. В данном Национальном отчете представлены основные результаты исследований, проводимых российскими геодезистами в 2011-2014 гг., по темам, соответветствующим направлениям деятельности Международной ассоциации геодезии (МАГ) Международного геодезического и геофизического союза (МГГС). Данный отчет подготовлен Секцией геодезии Национального геофизического комитета Российской академии наук. В данном отчете, подготовленном к XXVI Генеральной ассамблее МГГС (Чехия, Прага, 22 июня-2 июля 2015 г.), представлены основные результаты исследований в области геодезии, геодинамики, гравиметрии, создания геодезических систем отсчета, формы и гравитационного поля Земли, вращения Земли, теории геодезии и ее приложений. По понятным причинам, в отчет были включены не все результаты, полученные российскими учеными в области геодезии.

Singular spectral analysis of GRACE observations

Singular spectrum analysis of GRACE observations

Multichannel singular spectrum analysis in application to GRACE and Jason-1 satellites data

Multichannel singular spectrum analysis (MSSA) was applied to the Stokes coefficients of the temp... more Multichannel singular spectrum analysis (MSSA) was applied to the Stokes coefficients of the temporal gravity filed solutions obtained from the GRACE twin-satellite gravity mapping mission, and to the 10-days gridded maps of Sea Surface Height (SSH) time series from ...

Precise transformations between the international celestial and terrestrial reference frames are ... more Precise transformations between the international celestial and terrestrial reference frames are needed for many advanced geodetic and astronomical tasks including positioning and navigation on Earth and in space. To perform this transformation at the time of observation, that is for real-M. Kalarus (B) · W. Kosek time applications, accurate predictions of the Earth orientation parameters (EOP) are needed. The Earth orientation parameters prediction comparison campaign (EOP PCC) that started in October 2005 was organized for the purpose of assessing the accuracy of EOP predictions. This paper summarizes the results of the EOP PCC after nearly two and a half years of operational activity. The ultra short-term (predictions to 10 days into the future), short-term (30 days), and medium-term (500 days) EOP predictions submitted by the participants were evaluated by the same statistical technique based on the mean absolute prediction error using the IERS EOP 05 C04 series as a reference. A combined series of EOP predictions computed as a weighted mean of all submissions available at a given prediction epoch was also evaluated. The combined series is shown to perform very well, as do some of the individual series, especially those using atmospheric angular momentum forecasts. A main conclusion of the EOP PCC is that no single prediction technique performs the best for all EOP components and all prediction intervals.