Analysis of limitations on recovery of gravity field based on satellite gravity gradient data
Analysis of limitations on recovery of gravity field based on satellite gravity gradient data
复制标题
基于卫星重力梯度数据恢复重力场的局限性分析
DOI：
10.1016/j.geog.2020.11.005
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发表时间：
2021
影响因子：
2.4
通讯作者：
Annna R.F
中科院分区：
文献类型：
--
作者：
Wan Xiaoyun;Yu Jinhai;Liang Lei;Ran Jiangjun;Annna R.F
尽管卫星重力梯度数据在确定静态重力场模型的短波长部分方面发挥了很大作用，但它们恢复的重力场模型的长波长部分精度较差，导致在时变重力调查中的应用很少。这是由于重力梯度观测值的精度、重力梯度仪的测量带宽、卫星倾角等因素限制了重力梯度数据恢复重力场的精度。本文旨在分析这些限制因素对重力场恢复的影响，并探讨利用重力梯度观测值进行时变重力场探测的可能性。首先，对于任意卫星轨道倾角，给出了重力梯度各分量（即Txx，Tyy，Tzz，Txy，Txz和Tyz）的频率分布。结果表明，重力梯度各分量的最大频率相同，即l/Ts（l为重力场模型的阶数，Ts为轨道周期），且不受卫星轨道倾角的影响。其次，从理论上证明了极性带隙只影响低阶系数的原因。对大极隙进行了倾角为45°的数值试验。最后，考虑到超导重力梯度仪（SGG）与重力场梯度仪和稳态海洋环流探测仪（GOCE）相比，可以扩展测量带宽，提高梯度观测精度，讨论了利用重力梯度观测探测时变重力场的可能性。结果表明，SGG对MBW产生的误差为0.014 mE，小于GRACE重力场模型的时变重力梯度信号的误差（0.02 mE）。这表明SGG在时变重力探测中的潜力。
Although satellite gravity gradient data plays a great role in determining short-wavelength part of static gravity field model, accuracy of the long-wavelength part of gravity field model recovered by them are poor, which leads to only a few applications in time-variable gravity investigation. The reason is that some factors limit the accuracy of the gravity field recovered using gradient data, including accuracy of the gravity gradient observations, measurement bandwidth (MBW) of gradiometer, satellite inclination, etc. This paper aims at analyzing the influence of these limitations on gravity field recovery and discusses the possibility of time-variable gravity field detection by using gravity gradient observations. Firstly, for arbitrary satellite orbit inclination, we give the frequency distributions of all the components of gravity gradients (ie T x x, T y y, T z z, T x y, T x z and T y z,). The results show that the maximum frequency of each component of the gravity gradients is the same, ie l/T s (l is degree of the gravity field model, T s is the orbital periods), and it is not influenced by the inclination of the satellite orbits. Secondly, the paper gives a theory proof to explain why only the low orders of the coefficients are influenced by polar gaps. Big polar gaps are experimented by a numerical test with inclination of 45°. Finally, considering that the measurement bandwidth can be expanded and accuracy of gradient observations can be improved by superconducting gravity gradiometer (SGG) compared to gradiometer used in Gravity field and steady-state Ocean Circulation Explorer (GOCE), the possibility of detecting time-variable gravity using gravity gradient observations is discussed. The results show that the SGG creates errors in MBW with magnitude of 0.014 mE, which is smaller than the magnitude of the time-variable gravity gradient signals (ie, 0.02 mE) derived from Gravity Recovery and Climate Experiment (GRACE) gravity field models. This indicates the potential of SGG in time-variable gravity detection.