Conservative evaluation of the uncertainty in the LAGEOS-LAGEOS II Lense-Thirring test

Lorenzo Iorio

doi:10.2478/s11534-009-0060-6

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arXiv · 0710.1022

Conservative evaluation of the uncertainty in the LAGEOS-LAGEOS II Lense-Thirring test

Lorenzo Iorio

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Abstract

We deal with the test of the general relativistic gravitomagnetic Lense-Thirring effect currently ongoing in the Earth's gravitational field with the combined nodes Ωof the laser-ranged geodetic satellites LAGEOS and LAGEOS II. One of the most important source of systematic uncertainty on the orbits of the LAGEOS satellites, with respect to the Lense-Thirring signature, is the bias due to the even zonal harmonic coefficients J_L of the multipolar expansion of the Earth's geopotential which account for the departures from sphericity of the terrestrial gravitational potential induced by the centrifugal effects of its diurnal rotation. The issue addressed here is: are the so far published evaluations of such a systematic error reliable and realistic? The answer is negative. Indeed, if the difference ΔJ_L among the even zonals estimated in different global solutions (EIGEN-GRACE02S, EIGEN-CG03C, GGM02S, GGM03S, ITG-Grace02, ITG-Grace03s, JEM01-RL03B, EGM2008, AIUB-GRACE01S) is assumed for the uncertainties δJ_L instead of using their more or less calibrated covariance sigmas σ_{J_L}, it turns out that the systematic error δμin the Lense-Thirring measurement is about 3 to 4 times larger than in the evaluations so far published based on the use of the sigmas of one model at a time separately, amounting up to 37% for the pair EIGEN-GRACE02S/ITG-Grace03s. The comparison among the other recent GRACE-based models yields bias as large as about 25-30%. The major discrepancies still occur for J_4, J_6 and J_8, which are just the zonals the combined LAGEOS/LAGOES II nodes are most sensitive to.

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BibTeX RIS

Lorenzo Iorio. 2009-03-30. Conservative evaluation of the uncertainty in the LAGEOS-LAGEOS II Lense-Thirring test. https://doi.org/10.2478/s11534-009-0060-6

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