Detection of a New Large Free Core Nutation Phase Jump

Zinovy Malkin; Santiago Belda; Sadegh Modiri

doi:10.3390/s22165960

Detection of a New Large Free Core Nutation Phase Jump

Sensors (Basel). 2022 Aug 9;22(16):5960. doi: 10.3390/s22165960.

Authors

Zinovy Malkin¹, Santiago Belda^{2

3}, Sadegh Modiri⁴

Affiliations

¹ Pulkovo Observatory, St. Petersburg 196140, Russia.
² University of Alicante VLBI Analysis Centre (UAVAC), University of Alicante, 03080 Alicante, Spain.
³ Image Processing Laboratory (IPL)-Laboratory of Earth Observation (LEO), University of Valencia, 46980 Valencia, Spain.
⁴ Department Geodesy, Federal Agency for Cartography and Geodesy (BKG), 60322 Frankfurt am Main, Germany.

Abstract

We announce the detection of a new large jump in the phase of the free core nutation (FCN). This is only the second such large FCN phase jump in more than thirty years of FCN monitoring by means of a very long baseline interferometry (VLBI) technique. The new event was revealed and confirmed by analyzing two FCN models derived from a long-time series of VLBI observations. The jump started in 2021 and is expected to last until the late fall of 2022. The amplitude of the phase jump is expected to be approximately 3 rad, which is as much as 1.5 times larger than the first phase jump in 1999-2000. A connection of the new FCN phase jump with the recent geomagnetic jerk started in 2020 is suggested.

Keywords: Earth’s rotation; FCN phase variations; VLBI; celestial pole motion; free core nutation (FCN).

MeSH terms

Time Factors*

Grants and funding

Santiago Belda was partially supported by Generalitat Valenciana (SEJIGENT/2021/001), the European Union–Next Generation EU (ZAMBRANO 21-04) and Ministerio de Ciencia e Innovación (Spanish Project PID2020-119383GB-I00).