﻿ GRACE时变信号恢复方法对比分析
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 大地测量与地球动力学  2019, Vol. 39 Issue (2): 204-209  DOI: 10.14075/j.jgg.2019.02.018

引用本文

LIU Bingshi, ZOU Xiancai. Comparison and Analysis of GRACE Time-Varying Signal Recovery Methods[J]. Journal of Geodesy and Geodynamics, 2019, 39(2): 204-209.

Foundation support

National Natural Science Foundation of China, No. 41274033, 41874021; National Key Basic Research Program of China, No. 2013CB733301; Civil Aerospace "13th Five-Year" Preliminary Research Project.

About the first author

LIU Bingshi, postgraduate, majors in satellite geodesy, E-mail: bs.liu@whu.edu.cn.

文章历史

GRACE时变信号恢复方法对比分析

1. 武汉大学测绘学院，武汉市珞喻路129号，430079;
2. 武汉大学地球空间环境与大地测量教育部重点实验室，武汉市珞喻路129号，430079

1 数据处理方法 1.1 时变信号损失的成因及影响

 $\begin{array}{l} \;\;\;\;\mathit{\Delta H}\left( {\theta, \lambda } \right) = \frac{{a{\rho _{{\rm{ave}}}}}}{{3{\rho _{\rm{w}}}}}\mathop \sum \limits_{l = 0}^{{l_{{\rm{max}}}}} \mathop \sum \limits_{m = 0}^l {{\bar P}_{lm}}\left( {{\rm{cos}}\theta } \right) \cdot \\ \frac{{2l + 1}}{{1 + {k_l}}}{W_{lm}}\left( {\mathit{\Delta }{{\bar C}_{lm}}{\rm{cos}}\left( {m\lambda } \right) + \mathit{\Delta }{{\bar S}_{lm}}{\rm{sin}}\left( {m\lambda } \right)} \right) \end{array}$ (1)

 图 1 不同平滑半径下，高斯平滑Wl对阶数l的响应 Fig. 1 The response of Gaussian filter Wl on degree l under different smoothing radius

 图 2 等效水柱高空间分布 Fig. 2 The simulated equivalent water height
1.2 尺度因子法

 $\mathop \sum \limits_i^N {\left( {\mathit{\Delta }{h_{ij}}\left( t \right) - {k_{ij}}\mathit{\Delta }{{\tilde h}_{ij}}\left( t \right)} \right)^2} = {\rm{min}}$ (2)

 图 3 基于GLDAS水文数据不同陆地地表模式所获取尺度因子的全球分布 Fig. 3 Spatial distributions of scaling factors derived from GLDAS data
1.3 迭代恢复法

1.4 GRACE数据处理方法

2 时变信号恢复效果对比分析 2.1 不同恢复方法效果的时间序列分析对比

 图 4 不同信号恢复方法获得的区域水储量年际变化、长期趋势和周年振幅 Fig. 4 Interannual variation, long-term trend and annual amplitude of regional storage obtained by different recovery methods

2.2 不同恢复方法效果的空间分布分析对比

 图 5 不同信号恢复方法获得的亚洲部分地区水储量变化长期趋势 Fig. 5 Long-term trends of water storage in parts of Asia obtained by different recovery methods

 图 6 不同信号恢复方法获得的南美地区水储量长期变化趋势 Fig. 6 Long-term trends of water storage in south America obtained by different recovery methods

3 结语

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Comparison and Analysis of GRACE Time-Varying Signal Recovery Methods
LIU Bingshi1     ZOU Xiancai1,2
1. School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China;
2. Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan University, 129 Luoyu Road, Wuhan 430079, China
Abstract: In view of the phenomenon of time-varying signal weakening and leakage in the process of GRACE data preprocessing, the scaling factors method and the forward modeling method are used to recover the lost signals. CSR Mascon products are adopted to compare the effects of the two recovery methods from the perspective of time series and spatial distribution. Results show: 1) The scaling factors method is relatively simple to implement, but the result of the scaling factors is completely dependent on the prior model, and when the reliability of the selected model is poor, the reliability of the GRACE inversion results are affected. 2) The restoration process of the forward modeling method is constrained by the original GRACE observations, and can restore the long-term trend and periodic signals, but there may be signal over-recovery in some areas. In restoring GRACE time-varying signals, we suggest using the forward modeling method.
Key words: GRACE; signal leakage; signal recovery; scaling factors method; forward modeling method