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首页> 外文期刊>Advances in space research >The Role of Accelerometer Data Calibration within GRACE Gravity Field Recovery: Results from ITSG-Grace2016
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The Role of Accelerometer Data Calibration within GRACE Gravity Field Recovery: Results from ITSG-Grace2016

机译：加速度计数据校准在GRACE重力场恢复中的作用：ITSG-Grace2016的结果

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For more than 14 years, the Gravity Recovery and Climate Experiment (GRACE) mission has provided information about Earth's gravity field with unprecedented accuracy. The twin satellites GRACE-A and GRACE-B are both equipped with a three-axis electrostatic accelerometer, measuring the non-gravitational forces acting on the spacecraft. In order to make use of the uncalibrated Level-1B accelerometer (ACC1B) data during gravity field recovery, bias and scale parameters have to be estimated. The proposed calibration method is a two-step approach and makes use of modeled non-conservative accelerations. The simulated non-conservative accelerations serve as reference for the a priori accelerometer calibration, i.e. for the ACC1B data. During gravity field recovery the calibration parameters are re-estimated. Several calibration parameters for the GRACE accelerometers using different methods have already been published. The aim of our study was primarily to analyze the temperature-dependent behavior of the accelerometer scale factors and biases, and the impact of the parametrization of scale factors and biases on the recovered gravity field solutions; but not to obtain calibrated accelerometer data. Within the ITSG-Grace2016 release, the accelerometer biases are estimated daily using uniform cubic basis splines (UCBS), the scale factors are also estimated daily using a fully-populated scale factor matrix. Therefore, not only the scale factors in along-track, cross-track, and radial direction are estimated, but also the non-orthogonality of the accelerometer axes (cross-talk) and the misalignment between the Accelerometer Frame (AF) and Science Reference Frame (SRF) are taken into account. The time evolution of the estimated calibration parameters over the whole GRACE period (2002-04 to 2016-01) shows a clear temperature-dependency for both scale factors and biases. Using this new approach, the estimates of the C20 coefficient significantly improve, with results now comparable to Satellite Laser Ranging (SLR) solutions. Based on the achieved results, we suggest the presence of a clear temperature-dependent behavior and the presence of off-diagonal elements in the accelerometer scale factor matrix.
机译：十四年来，重力恢复和气候实验（GRACE）任务以前所未有的准确性提供了有关地球重力场的信息。双卫星GRACE-A和GRACE-B都配备了三轴静电加速度计，用于测量作用在航天器上的非重力。为了在重力场恢复过程中使用未校准的Level-1B加速度计（ACC1B）数据，必须估算偏差和比例参数。所提出的校准方法是一种两步方法，并利用建模的非保守加速度。模拟的非保守加速度用作先验加速度计校准的参考，即ACC1B数据的参考。在重力场恢复期间，将重新估计校准参数。已经发布了使用不同方法的GRACE加速度计的几个校准参数。我们研究的目的主要是分析加速度计比例因子和偏差的温度相关行为，以及比例因子和偏差的参数化对恢复的重力场解的影响；但无法获得校准的加速度计数据。在ITSG-Grace2016版本中，每天使用统一的三次基样条（UCBS）估算加速度计偏差，还使用完全填充的比例因子矩阵每天估算比例因子。因此，不仅要估算沿航迹，交叉航迹和径向的比例因子，还要估算加速度计轴的非正交性（串扰）以及加速度计框架（AF）与《科学参考》之间的未对准帧（SRF）被考虑在内。估计的校准参数在整个GRACE期间（2002-04至2016-01）的时间演变表明，比例因子和偏差均具有明显的温度依赖性。使用这种新方法，C20系数的估计值显着提高，其结果现在可与卫星激光测距（SLR）解决方案相比。基于获得的结果，我们建议在加速度计比例因子矩阵中存在明确的温度依赖性行为和非对角线元素。

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