Correction to “Determination of long‐term changes in the Earth's gravity field from satellite laser ranging observations” by M. K. Cheng, C. K. Shum, and B. D. Tapley

Evaluation of a possible upgrade of the IAU 2006 precession

“…Cheng & Tapley (2004) found from 28-year SLR observational data ) a secular decrease of J 2 at a rate of (−2.7 ± 0.4) × 10 −9 cy −1 , which is close to the value used in the IAU model (cf. Eq.…”

On the measurement of the Lense–Thirring effect using the nodes of the LAGEOS satellites, in reply to “On the reliability of the so-far performed tests for measuring the Lense–Thirring effect with the LAGEOS satellites” by L. Iorio

“…In regard to other conceivable error sources, a possible bias in our measurement of µ might be due to some "imprint" or "memory" of the a priori value of the Lense-Thirring effect used in the determination of the gravity model [see: (Ciufolini et al 1997)]. The author of (Iorio 2005) is mentioning this potential source of error in section 3.2.6 "The a priori "memory" effect of the Lense Thirring signature on the adopted Earth gravity model on the Earth (Cheng, Shum and Tapley 1997) gravity model used". The Earth gravity field model EIGEN-GRACE02S has been obtained using the observations of the GRACE satellites only and by using a set of models and parameters to describe the orbital perturbations, including some a priori, theoretical, value of the Lense-Thirring effect, indeed EIGEN-GRACE02S has been obtained without the Lense-Thirring effect in the data analysis.…”

“…These changes hold information about the dynamics of Earth and its anelastic response to tidal forcing. Estimation of the secular rates for the zonal harmonics therefore has been a high priority research topic of space geodesy for many years now, with a considerable number of independent results in the literature (Yoder et al 1983, Rubincam 1984, Gegout and Cazenave 1991, Nerem et al 1993, Cheng et al 1993, Cazenave, Gegout and Ferbat 1996, Nerem and Klosko 1996, Eanes and Bettadpur 1996, Cheng, Shum and Tapley 1997, Devoti et al 1999, Cox, Klosko and Chao 2000. The majority of these results were obtained from the analysis of long time intervals spanning several decades of data obtained from several satellites including the two LAGEOS, Starlette, Ajisai, Stella, BE-C and the two ETALONs.…”

Commission 19: Rotation of the Earth

“…During the past triennium, investigations in the U.S. of the Earth's time varying rotation followed a number of themes, including theoretical studies (Gross, 2011), tidal variations (Gross, 2009a(Gross, , 2009b(Gross, , 2009cDickman, 2010;Dickman and Gross, 2010;Gross and Dickman, 2011), glacial isostatic adjustment (Matsuyama et al, 2010;Mitrovica and Wahr, 2011), effects of global geophysical fluids (Dey and Dickman, 2010;Dickey et al, 2010;Landerer et al, 2009;Marcus et al, 2010;Nastula et al, 2009;Schindelegger et al, 2011;), effects of earthquakes (Gross and Chao, 2010), effects of the core (Buffett, 2010a(Buffett, , 2010bBuffett et al, 2009;Dickey and de Viron, 2009;Dickey et al, 2011), comparisons with gravity measurements (Cheng et al, 2011;Gross et al, 2009;Jin et al, 2010Jin et al, , 2011, and improving predictions (Chin et al, 2009;Gambis and Luzum, 2011;42 DIVISION I / COMMISSION 19 Gambis et al, 2011;Kalarus et al, 2010;Luzum and Nothnagel, 2010). Attention has been given to the use of atmospheric models to investigate the changes in Earth rotation that might be expected due to climate variability and possible secular changes The most important IAG meetings held in 2009-2011 were:…”