Long-term Earth Orientation Monitoring Using Various Techniques

Abstract

A continuous composite series of polar motion components extending from 1846 until now called EOP (IERS) C01 is available at the Earth Orientation Section of the Central Bureau of the IERS. This series is the basis of the IERS system. It relies on different series derived from optical astrometry until 1972 and geodetic techniques since. It is given at 0.1 year intervals (1846–1889) and 0.05 year intervals (1890-now). Its accuracy has dramatically improved from 100 mas in 1846 to about 0.2 mas at present.Now the IERS combined solutions involve mainly the contributions of VLBI, GPS and SLR techniques. It is regularly recomputed to take advantage of the improvement of the various recent individual contributions and of the refinement of the analyses procedures.The objective of this paper is to describe this long-term polar motion series and to present the evolution and the state of the art of the multi-technique EOP combined solutions and the predictions regularly computed at the IERS/CB.

Low-Frequency Variations, Chandler and Annual Wobbles of Polar Motion as Observed Over One Century

“…Its uncertainty has dramatically improved from 100 mas in 1846 to about 0.2 mas today. A summary of the contributions of observational techniques to Earth rotation monitoring, and the evolution of the increased precision obtained since 1846 can be found in Gambis (2000).…”