| 利用运动学轨道提高GRACE时变重力场解算 |
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| 引用本文： | 杨帆,王长青,许厚泽,钟敏,周泽兵.利用运动学轨道提高GRACE时变重力场解算[J].地球物理学报,2017,60(1):37-49. |
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| 作者姓名： | 杨帆 王长青 许厚泽 钟敏 周泽兵 |
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| 作者单位： | 1. 华中科技大学物理学院地球物理研究所, 武汉 430074;2. 中国科学院测量与地球物理研究所大地测量与地球动力学国家重点实验室, 武汉 430077 |
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| 基金项目： | 国家重大科学研究计划（2013CB733305，2012CB957703），国家自然科学基金（41131067，41431070），国家测绘地理信息局测绘基础研究基金（14-01-06）和地理信息工程国家重点实验室开放课题（SKLGIE2015-M-1-3）联合资助. |
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| 摘 要： | 基于变分方程法,本文利用GARCE高精度K波段星间测速数据KBRR,结合德国格拉茨大学发布的运动学轨道和GFZ发布的简动力学轨道作为两种伪观测值,分别解算了2005-2010年60阶全球时变重力场模型Hust-IGG01与Hust-IGG02.通过与GRACE官方机构发布的模型和其他国际主流权威模型进行对比,发现基于运动学轨道结合KBRR解算的模型Hust-IGGO1优于基于简动力学轨道结合KBRR解算的模型Hust-IGG02:在重力场系数C_(20)时间序列的统计数据上,Hust-IGG01比Hust-IGG02更接近SLR结果,在如C_(60)、C_(70)、C_(80)以及C_(90)等重力场低阶项上的数学统计均更接近CSR RL05;Hust-IGG01的重力场系数误差分布和GFZ RL05在同一水平,而Hust-IGG02的误差估计过于乐观;Hust-IGG02在主要质量变化区域上存在5%~10%信号低估,而Hust-IGG01能完全达到国际主流机构利用GPS观测数据的解算水平,Hust-IGG01与官方机构CSR、JPL和GFZ最新模型在格陵兰岛的冰川消融年际趋势分别是-125.4、-125.4、-127.3、-124.3 Gt·a~(-1),在亚马逊流域的平均等效水高周年振幅分别是17.56、17.40、17.46、17.22 cm,在撒哈拉沙漠的平均等效水高均方差分别是0.87、0.77、1.10、0.87 cm;另外在Hust-IGG01的实际应用上,本文分析了全球32个主要流域质量变化的年际趋势、周年振幅和半周年振幅三种信号模式,统计结果显示Hust-IGG01与CSR RL05结果基本吻合.
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| 关 键 词： | GRACE 时变重力场 运动学轨道 简动力学轨道 等效水高 |
| 收稿时间： | 2016-04-18 |
Towards a more accurate temporal gravity model from GRACE observations through the kinematic orbits |
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| YANG Fan,WANG Chang-Qing,HSU Hou-Tse,ZHONG Min,ZHOU Ze-Bing.Towards a more accurate temporal gravity model from GRACE observations through the kinematic orbits[J].Chinese Journal of Geophysics,2017,60(1):37-49. |
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| Authors: | YANG Fan WANG Chang-Qing HSU Hou-Tse ZHONG Min ZHOU Ze-Bing |
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| Institution: | 1. Institute of Geophysics, Huazhong University of Science and Technology, Wuhan 430074, China;2. State Key Laboratory of Geodesy and Earth's Geodynamics Chinese Academy of Sciences, Wuhan 430077, China |
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| Abstract: | Based on the GRACE Level 1b raw data from 2005 to 2010, we have successfully produced an unconstrained monthly gravity field model (Hust-IGG01) up to d/o 60. Unlike the official data-processing centers, we employ the kinematic orbits instead of the GPS measurements as the pseudo observations. Meanwhile, an alternative model (Hust-IGG02) using the reduced-dynamic orbits as the pseudo observations is provided as well. We aim to understand the impacts of orbit pseudo observations on the accuracy of the ultimate gravity products. To this end, Hust-IGG01 and Hust-IGG02 are fully compared to each other, such that we are able to identify which type of orbit pseudo observations is more desired for the gravity inversion. Experiments demonstrate that Hust-IGG01 performs better in terms of signal to noise level than Hust-IGG02 in the following aspects:(a) Hust-IGG01 improves the estimation of geopotential coefficients at low degrees, e.g., C20 C60 C70 C80 C90, which are closer to SLR or CSR RL05 results; (b) the induced formal error of Hust-IGG01 is appropriate and comparable to that of GFZ RL05a, while Hust-IGG02 poses too optimistic formal error; (c) over three typical regions of interest (Amazon, Greenland and Sahara), the mass variation derived from Hust-IGG02 has been under-estimated by about 5%~10% with respect to those from the official products, while Hust-IGG01 has achieved a fairly comparable accuracy. The latter is supported by the numerical results such as:the yearly trend of glacial melting over Greenland derived from Hust-IGG01, CSR RL05, GFZ RL05a and JPL RL05 are -125.4 Gt·a-1, -125.4 Gt·a-1, -127.3 Gt·a-1 and -124.3 Gt·a-1, respectively; the annual amplitude of mass change in terms of EWH (equivalent water height) over Amazon is 17.56 cm, 17.40 cm, 17.46 cm and 17.22 cm, respectively; the RMS of mass change over Sahara desert is 0.87 cm, 0.77 cm, 1.10 cm and 0.87 cm, respectively. An additional validation is undertaken as well, to investigate the performance of Hust-IGG01 on the scale of basins, and the results demonstrate that the induced annual amplitude, semi-annual amplitude and yearly trend of mass variations agree with those of CSR RL05 over the 32 selected major river basins. In summary, our comparisons above suggest that an appropriate kinematic orbit is more beneficial than the reduced-dynamic orbits, for the accurate gravity recovery from the GRACE observations. |
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| Keywords: | GRACE Temporal gravity field Kinematic orbit Reduced-dynamic orbit Equivalent water height |
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