Adjustment of EOP and gravity field parameter from SLR observations
Adjustment of EOP and gravity field parameter from SLR observations
复制标题
根据SLR观测调整EOP和重力场参数
DOI：
--
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
D. Angermann
中科院分区：
文献类型：
--
作者：
M. Bloßfeld;H. Müller;D. Angermann
卫星激光测距（SLR）提供了一致估计站位、地球自转参数（ERPs）和低阶重力场参数的潜力。此外，与卫星轨道有关的参数，如开普勒元素或经验加速度，可以在一次共同调整中估计出来。由于这些参数之间存在较高的相关性，因此联合调整是一项很大的工作。虽然SLR提供了高度精确的UT1-UTC的一阶导数，即一天的长度（LOD），但LOD与上升节点之间的相关性系统性地扭曲了估计的参数。估计的UT1-UTC值相对于国际地球自转和参考系统服务（IERS） 08 C04时间序列显示出明显的漂移，该时间序列随时间的变化不是严格的线性。在本研究中，我们利用LAGEOS 1和LAGEOS 2卫星的观测数据量化了对估计UT1-UTC值的系统影响。此外，我们讨论了如何通过首先使用更长的弧长或其次在解决方案中包括对多个卫星的观测来降低高相关性。利用ier08 C04时间序列对得到的UT1-UTC值进行验证。在解内，估计了二阶和二阶重力场参数。为了验证，将估计系数与空间研究中心（CSR）的时间序列进行了比较。1 LOD与卫星激光测距（SLR）相关因子是估计卫星站位、erp和轨道参数与地球重力场低次次球谐波一致的主要技术。一致性估计的主要工作是卫星相关参数的高度相关性，如开普勒元素或经验加速度，UT1-UTC的一阶导数，称为白昼长度（LOD），以及重力场参数。erp与轨道元之间的关系如式(1)所示[Rothacher et al., 1999]。卫星的纬度角变化率是用近地点角变化率和平均异常变化率计算的。是通用时间与恒星时间的比值（）。这些量的长期变化率除其他外，由(i)与（ii）交叉轨迹经验加速度的正弦项或（iii）大地进动或透镜-蒂林效应等相对论性效应引起。根据[Beutler， 2005]计算的长期比率。
Satellite Laser Ranging (SLR) provides the potential to estimate consistently station positions, Earth Rotation Parameters (ERPs) and gravity field parameters of low degree and order. Additionally, parameters which are related to the satellites orbit like the Keplerian elements or empirical accelerations could be estimated within one common adjustment. Since there are high correlations of these parameters among each other, the combined adjustment is a big effort. Although SLR provides highly accurate measurements of the first derivative of UT1-UTC, the Length-of-Day (LOD), the correlation between LOD and the ascending node distorts the estimated parameters systematically. The estimated UT1-UTC values show a significant drift relative to the International Earth Rotation and Reference Systems Service (IERS) 08 C04 time series which is not strictly linear over time. In this study we quantify the systematic effects on the estimated UT1-UTC values using observations of the satellites LAGEOS 1 and LAGEOS 2. Furthermore, we discuss how the high correlations could be reduced by firstly using longer arc lengths or secondly including observations to more than one satellite in the solution. The gained values of UT1-UTC are validated w.r.t. the IERS 08 C04 time series. Within the solution, gravity field parameters of degree and order two are estimated. For validation, the estimated coefficients are compared to a time series of the Center for Space Research (CSR). 1 Correlation factors of LOD, and Satellite Laser Ranging (SLR) is the primary technique to estimate consistently station positions, ERPs and orbit parameters of the satellites together with the spherical harmonics of low degree and order of the Earth gravity field. The big effort of the consistent estimation are the high correlations of the satellite-dependent parameters like Keplerian elements or empirical accelerations, the first derivative of UT1-UTC, called length of day (LOD), and the gravity field parameter . The relationship between the ERPs and the orbital elements are given in equation (1) [Rothacher et al., 1999]. The rate of change of the argument of latitude of a satellite is calculated by with being the rate of change of the argument of perigee and being the rate of change of the mean anomaly. is the ratio of universal time to sidereal time ( ). The secular rate of change of these quantities is caused inter alia by (i) the even zonal spherical harmonics with , (ii) by the sine term of the cross-track empirical acceleration or (iii) by relativistic effects like the Geodetic Precession or the Lense-Thirring Effect. The secular rate of due to is calculated with [Beutler, 2005]