The goal of this presentation is to report the latest progress in creation of the next generation of VLBI-based International Celestial Reference Frame, ICRF3. Two main directions of ICRF3 development are improvement of the S/X-band frame and extension of the ICRF to higher frequencies. Another important task of this work is the preparation for comparison of ICRF3 with the new generation optical frame GCRF expected by the end of the decade as a result of the Gaia mission.
In this National Report are given major results of researches conducted by Russian geodesists in 2015-2018 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 XXVII General Assembly of IUGG (Canada, Montreal, 8-18 July 2019), 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.
Several attempts to discover the FICN signal in VLBI nutation series made during last years failed. In this paper, we present some results of our further steps in this direction, unfortunately not successful either. We investigated several VLBI CPO series by means of spectral and wavelet analysis. It has been shown that there are several periodic signals with close amplitude around the expected FICN period without any prevailing one that can be reliably associated with the FICN. The most interesting for further analysis is a relatively stable oscillation with period of about 750–800 days, which is, however, beyond the intervals predicted in other studies. It seems to be necessary to improve theoretical estimates of the FICN period to make its search in the observational data more promising.
The paper presents results of modeling various variations of the Universal Time (UT1). To develop a variation models, UT1 observations from 1901 to 2020 published by the International Earth Rotation and Reference Systems Service (IERS) were used. Using the developed method, the main variations are identified from the diverse spectrum of irregularities in the Earth’s rotation, the models of which are presented as a superposition of a limited number of harmonic components. The results obtained in this paper are important for improving the accuracy of predictions of Universal Time.
Context.Radio source catalogues (RSCs) obtained from very long baseline interferometry (VLBI) observations are recommended by the International Astronomical Union (IAU) as realizations of the International Celestial Reference Frame (ICRF). As the accuracy of the VLBI observations is improving with time, development of more accurate methods of RSC construction is a topical problem.
Investigations of the anomalies in the Earth rotation, in particular, the polar motion components, play an important role in our understanding of the processes that drive changes in the Earth's surface, interior, atmosphere, and ocean. This paper is primarily aimed at investigation of the Chandler wobble (CW) at the whole available 163-year interval to search for the major CW amplitude and phase variations. First, the CW signal was extracted from the IERS (International Earth Rotation and Reference Systems Service) Pole coordinates time series using two digital filters: the singular spectrum analysis and Fourier transform. The CW amplitude and phase variations were examined by means of the wavelet transform and Hilbert transform. Results of our analysis have shown that, besides the well-known CW phase jump in the 1920s, two other large phase jumps have been found in the 1850s and 2000s. As in the 1920s, these phase jumps occurred contemporarily with a sharp decrease in the CW amplitude.
Two methods of prediction of the Pole coordinates and TAI-UTC were tested -- extrapolation of the deterministic components and ARIMA. It was found that each of these methods is most effective for certain length of prognosis. For short-time prediction ARIMA algorithm yields more accurate prognosis, and for long-time one extrapolation is preferable. So, the combined algorithm is being used in practice of IAA EOP Service. The accuracy of prognosis is close to accuracy of IERS algorithms. For prediction of nutation the program KSV-1996-1 by T. Herring is being used.
This report submitted to the International Association of Geodesy (IAG) of the International Union of Geodesy and Geophysics (IUGG) contains results obtained by Russian geodesists in 2007-2010. In the report prepared for the XXV General Assembly of IUGG (Australia, Melbourne, 28 June - 7 July 2011), 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. The period from 2007 to 2010 was still difficult for Russian geodesy mainly due to the permanent reformation of state geodetic administration as well as state education structure and organization. The report is organized as a sequence of abstracts of principal publications and presentations for symposia, conferences, workshops, etc. Each of the report paragraphs includes a list of scientific papers published in 2007-2010 including those prepared in cooperation of Russian scientists and their colleagues from other countries. Some interesting international and national scientific events are reflected in the text too. For some objective reasons not all results obtained by Russian scientists on the problems of geodesy are included in the report.
