动力法校准GRACE星载加速度计
Calibration of the Accelerometers OnboardGRACE with the Dynamic Method
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摘要: 研究了GRACE星载加速度计的动力法校准。联合精密轨道、星间距离变率同时估计重力场模型参数和加速度计校准参数,获得了SRF(satellite reference frame)下的比例系数和偏差参数时间序列,100阶重力场模型的大地水准面累积误差为4cm,在相应波段上优于CSR(center for space research)同时段的月重力场模型精度。以上述整体解算的结果为参照,对固定重力场模型参数的校准方案进行了检验,发现SRF框架下的非保守力差值最高可达10-8 m·s-2量级,认为固定重力场模型的方法难以充分发挥GRACE加速度计的测量能力。本文研究结果可为后续的大规模卫星重力测量数据处理提供科学的依据,也能为开展相关科学应用提供可靠的非保守力数据。Abstract: A dynamic method for the calibration of the GRACE accelerometers was the focus of this study. The calibration parameters of the accelerometers was estimated using an integrated adjustment combining the precise orbit (PO),K-band range rate(kRR),and the earth gravity model(EGM).The scales and the time series of the biases were derived;the accumulated geoid error of the recovered EGM is 4cm till 100 degrees,which is superior to that from the monthly EUM derived by center for space research(CSR) at the same spatial resolution.These results were used as a reference to check the strategy for calibrating the accelerometer with a fixed EGM background.It iwas found that the magnitude of the differences was on the order of 10-8m·s-2for the non-conservative forces derived from the calibration parameters.Thus,it was concluded that the strategy for fixing the EGM cannot fully utilize the ability of the accelerometer.Our results provide a scientific basis for the further processing of satellite gravimetry data in a routine mode,and can also provide reliable non-conservative forces for interdisciplinary scientific research.