单加速度计模式下的GOCE卫星重力场建模方法研究

GOCE卫星由于加速度计的特殊安装方式,其非保守力主要由普通模式的组合加速度提供,使得单个加速度计的特征更难提取.本文首次采用实测数据,研究了单加速度计模式下的高低跟踪数据处理.利用GOCE任务2009年(2009-11—2009-12)的实测数据,分别以GOCE卫星梯度仪坐标系三个坐标轴正向的加速度计为研究对象,利用1s间隔的高采样轨道数据,采用动力法同时进行卫星重力场建模和加速度计的精密校准.为了克服两极地区的数据缺失对重力场模型低次系数的影响,即所谓的极空白问题,引入同期GRACE卫星的观测数据,采用方差分量估计方法,建立了GRACE/GOCE卫星跟踪卫星重力场模型WHU-GRGO-SST.该模型完全到100阶次,经6169个美国GPS水准点数据检验,在同阶次上与EGM2008和GGM05S的精度水平相同.分析发现,GOCE卫星的加速度计偏差参数存在显著的漂移,也显示了单加速度计模式处理GOCE高低跟踪数据的优势.本文的研究成果为建立静态高分辨率、高精度的GRACE/GOCE重力场模型提供了更严密的模型与技术方案,同时也为GOCE卫星梯度仪校准,以及梯度数据的深入分析提供了重要的参考信息.

Study on the earth gravity modeling by GOCE in individual accelerometer mode

Because of the special configuration of the accelerometers in the gradiometer onboard GOCE, the non-conservative forces of GOCE is provided by the common mode accelerations, which makes it more difficult to distinguish the characteristics of the accelerometers. In this article, in situ data was used for the first time to study the processing of the high-low satellite-to-satellite tracking data in individual accelerometer mode, including the precise orbit with 1s interval in 2009 (2009-11—2009-12) and the observations of the accelerometers which are on the positive axis of the gradiometer reference frame. The satellite-only earth gravity modeling and precise calibration of the accelerometers are studied with the dynamic method. To overcome the so called polar gap problem, or the data loss in the polar regions and the caused deterioration on the low order spherical coefficients of the earth gravity model, the GRACE data in the same time span are combined with the variance component estimation method, and the model WHU-GRGO-SST is built complete to degree and order 100. It has the same accuracy as the EGM2008 and GGM05S compared to the 6169 GPS/leveling benchmarks in USA when truncated to the same degree. The analysis shows that the bias parameters of the GOCE accelerometers have significant drifts. The results demonstrate the superiority of the methods used in this article and provide a more strict foundation for the building of a combined static GRACE/GOCE satellite gravity model with high resolution and high accuracy, and the auxiliary products server for the calibration of the GOCE gradiometer and profound processing of satellite gravity gradients.