China
Africa
Explore chapters and articles related to this topic
Co-ordinates of heaven and Earth
Published in Martin Vermeer, Antti Rasila, Map of the World, 2019
Together, all these quantities go by the name of Earth Orientation Parameters (EOP). Their changes over time are continuously monitored, and measured values published, by the International Earth Rotation and Reference Systems Service (IERS) on the Internet. The geophysical causes of the temporal changes in these parameters are well understood and can be modelled; one of the main causes of the Chandler wobble are the changes in pressure in the world's oceans and atmosphere (Gross, 2000).
Analysis on the differences between EOP 08C04 and EOP 14C04 related to the Earth rotation characteristics
Published in Journal of Spatial Science, 2022
Zhangzhen Sun, Tianhe Xu, Shi'e Zhou, Nan Jiang, Chunhua Jiang, Yuguo Yang
The Earth’s rotational movement characterises the situation of the whole Earth state, as well as the interaction between the various spherical layers forming the Earth’s core, mantle, crust and atmosphere (Zheng and Yu 1996). The Earth Orientation Parameters (EOP) are often used to reflect changes in the Earth’s rotation, including precession-nutation, Polar Motion (PM), Universal Time (UT1-UTC) and Length-of-Day (LOD, the derivative of UT1-UTC). The PM and UT1-UTC/LOD are called Earth Rotation Parameters (ERP). With the rapid development of modern space navigation and deep space exploration, the highest requirements are urged for the accuracy of ERP monitoring and prediction (Kong et al. 2010). Researchers have established a large number of high-precision prediction algorithms based on the existing observations and the characteristics of ERP (Schuh et al. 2002, Niedzielski and Kosek 2008, Kalarus et al. 2010, Kosek 2012, Sun et al. 2015, Lei 2016, Jia et al. 2017, Dill et al. 2019, Modiri et al. 2018). With the improvement of space and geodetic techniques (VLBI, SLR, GNSS and DORIS), the measurement accuracy of the Earth’s rotation has increased by 1–2 orders of magnitude. The ERP product is currently published by the International Earth Rotation Service (IERS), and the formal accuracy of PM x component is 27, PM y component is 25, UT1-UTC is 3.4 and LOD is 10 (Bizouard 2018b).
One-step method for predicting LOD parameters based on LS+AR model
Published in Journal of Spatial Science, 2021
Fei Wu, Guobin Chang, Kazhong Deng
Earth orientation parameters (EOP) characterise the state of motion of Earth and reflect the coupling process between the solid Earth and the atmosphere, oceans, mantle, and the Earth’s core at various temporal and spatial scales (Lambeck 1980). EOP include Earth rotation parameters (ERP), and precession and nutation parameters. ERP include parameters that describe changes in the Earth’s rotation rate (change of length of day and UT1 − UTC) and parameters that represent Earth’s instantaneous spin axis relative to its surface or epoch-horizontal polar motion. Many excitation sources produced by geophysical processes (movement of matter within Earth, seismic activity, movement of the atmosphere and oceans, etc.) affect the Earth’s rotation. Thus, EOP contain a wealth of geodynamics information (McCarthy 1996). It plays a significant role in several applications, including the determination of high-precision satellite orbits, spacecraft tracking, laser measurements, and deep space exploration. These parameters are required to achieve mutual conversion between celestial and terrestrial reference frames. The development of modern geodetic techniques has substantially facilitated the acquisition of high-precision ERP. However, due to complex data processing, there is a certain delay in calculating high-precision EOP. In some practical applications, real-time EOP must be acquired in advance. For example, when a satellite enters autonomous orbit determination mode, the ground control system can no longer upload the latest EOP data to complete conversion between the GCRS and ITRS, and can only guarantee conversion between the two systems by forecasting EOP data. The level of precision of EOP forecasting directly affects the analytical accuracy of scientific applications, such as space tracking measurements and precision orbit determination (Gambis and Luzum 2011, Wang et al. 2017) and is the main factor affecting autonomous orbit determination. Therefore, the study of EOP forecasting algorithms has great significance.