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A possible interrelation between Earth rotation and climatic variability at decadal time-scale

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Geodesy and Geodynamics 2016年第3期7卷 216-222页

作者： Leonid Zotov c.Bizouard c.k.shum National Research University Higher School of Economics Moscow Institute of Electronics and Mathematics Lomonosov Moscow State University Sternberg Astronomical Institute SYRTE Observatoire de Paris PSL Research University CNRS Sorbonne Universités UPMC Univ Division of Geodetic Science School of Earth Sciences The Ohio State University State key Laboratory of Geodesy and Earth's Dynamics Institute of Geodesy & Geophysics Chinese Academy of Sciences

Using multichannel singular spectrum analysis （MSSA） we decomposed climatic time se- ries into principal components, and compared them with Earth rotation parameters. The global warming trends were initially subtracted. Similar quasi 60 and 20 year periodic os- cillations have been found in the global mean Earth temperature anomaly （HadcRUT4） and global mean sea level （GMSL）. Similar cycles were also found in Earth rotation variation. Over the last 160 years multi-decadal change of Earth＇s rotation velocity is correlated with the 60-year temperature anomaly, and chandler wobble envelope reproduces the form of the 60-year oscillation noticed in GMSL. The quasi 20-year oscillation observed in GMSL is correlated with the chandler wobble excitation. So, we assume that Earth＇s rotation and climate indexes are connected. Despite of all the clues hinting this connection, no sound conclusion can be done as far as ocean circulation modelling is not able to correctly catch angular momentum of the oscillatory modes.

关键词： Earth rotation climate change Sea level Multichannel singular spectrumanalysis (MSSA) North Atlantic Oscillation (NAO) Atlantic Multi-decadal Oscillation(AMO)

Antarctic-wide annual ice flow maps from Landsat 8 imagery between 2013 and 2019

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International Journal of Digital Earth 2021年第5期14卷 597-618页

作者： Qiang Shen Hansheng Wang c.k.shum Liming Jiang Houtse Hsu Fan Gao Yingli Zhao State key Laboratory of Geodesy and Earth’s Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhanPeople’s Republic of China Division of Geodetic Science School of Earth SciencesThe Ohio State UniversityColumbusOhioUSA college of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijingPeople’s Republic of China

Ice velocity constitutes a key parameter for quantifying ice-sheet discharge rates and is thus crucial for improving the coupled models of the Antarctic ice sheet towards accurately predict its contribution to future global sea-level ***,in Antarctica,high-resolution and continuous ice velocity estimates remain elusive,which is key to unravel Antarctica’s present-day ice mass balance ***,we present a suite of newly estimated Antarctic-wide,annually-sampled ice velocity products at 105-m grid-spacing observed by Landsat 8 optical images *** first describe a procedure that can automatically calibrate and integrate ice displacement maps to generate Antarcticwide seamless ice velocity *** annual ice velocity mosaics are assembled using a total of 250,000 displacement maps inferred from more than 80,000 Landsat 8 images acquired between December 2013 and April *** new annual Antarctic ice velocity data product exhibits an improved quantification of near-decadal Antarctic-wide ice flow,and an opportunity to investigate ice dynamics at a higher spatial resolution and annual sampling,as compared to existing data *** studies confirmed improved accuracy and consistency of this new data product,when compared with independently estimated optical and radar ice velocity data products,as well as in situ data.

关键词： Antarctica ice velocity Landsat 8

characterizing receiver clock behaviors onboard Low Earth Orbiters:A case study of GRAcE satellites

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Geodesy and Geodynamics 2019年第4期10卷 276-281页

作者： Tzu-Pang Tseng c.k.shum Ting-Yi Yang Geoscience Australia Jerrabomberra Ave&Hindmarsh DriveSymonstonACT2609Australia Division of Geodetic Science School of Earth SciencesThe Ohio State University125 South Oval MallColumbusOH43210USA Institute of Geodesy and Geophysics Chinese Academy of SciencesWuhanHubei430077China

Accurate estimation of clocks, for example for the Gravity Recovery And climate Experiment(GRAcE)twin-satellites, is a critical part of precise orbit determination(POD) that ensures temporal gravity inversion. characterizing the periodic variations of the receiver clocks is critical for precise clock modeling and prediction. In this study, the receiver clock is estimated using two different POD procedure: kinematic and reduced-dynamic approaches. choices and the number of orbital parameters estimated in POD process affect the clock estimates, e.g., there are 8895 and 34,560 total parameters in the reduced-dynamic and kinematic approaches, respectively. In the both cases, the periodic variations of GRAcE receiver clock are mainly dominated by the GPS orbit period, as well as once-(1-pr) and twiceper-revolution(2-pr) effects. Here the 1-pr effect is coupled with the relativistic effect, resulting in a difficulty to separate both signals. The clock amplitudes caused by the GPS orbit period, 1-pr and 2-pr are about 0.1, 0.03 and 0.01 ns, respectively. The GPS orbit period is almost one order magnitude larger than the 1-and 2-pr effect. The 0.1-ns amplitude of the 12-h periodic variation is equivalent to a 3-cm error in range. Such a systematic error should be considered in the receiver clock modeling for both the improvement of positioning accuracy and the reduction of number of unknown parameters, if the precise point positioning(PPP) technique is used for the orbit determination of the GRAcE.

关键词： GPS GRAcE Precision orbit determination clock modeling

The rigorous adjustment of the global mean sea level budget during 2005-2015

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Geodesy and Geodynamics 2021年第3期12卷 175-180页

作者： H.Bâki Iz T.Y.Yang c.k.shum Division of Geodetic Science School of Earth SciencesThe Ohio State UniversityColumbusOHUSA

Global mean sea level budget is rigorously adjusted during the period *** emphasis is to provide the best estimates for the linear rates of changes(trends)of the global mean sea level budget components during this period subject to the constraint:Earth’s hydrosphere conserves *** newly simultaneously adjusted trends of the budget components suggest a larger correction for the global mean sea level trend implicated by the other budget components’trends under the budget *** simultaneous estimation of the linear trends of the budget components subject to the constraint for closure improves their uncertainties and enables a holistic assessment of the global mean sea budget,which has implications for future sea level science studies,including the future Intergovernmental Panel on climate change(IPcc)Assessment Reports,and the US climate Assessment Reports.

关键词： climate change Misclosure Global mean sea level Rigorous adjustment

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利用海洋重力场变化分析洋底板块运动

地球物理学报 2020年第7期63卷 2506-2515页

作者：李倩倩鲍李峰 c.k.shum 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 中国科学院大学北京100049 美国俄亥俄州立大学地球科学学院大地测量科学系美国哥伦布43210

洋底板块运动是地球动力学和全球变化研究的重要内容.本文根据质量迁移与地球外部重力场变化的对应关系,利用不同时期测高资料推算的1995-2019全球海洋重力场变化结果,反演分析全球洋底板块运动特征.研究表明,板块汇聚边界、板块内无震... 详细信息

洋底板块运动是地球动力学和全球变化研究的重要内容.本文根据质量迁移与地球外部重力场变化的对应关系,利用不同时期测高资料推算的1995-2019全球海洋重力场变化结果,反演分析全球洋底板块运动特征.研究表明,板块汇聚边界、板块内无震海岭、海山群、断裂带等区域重力异常变化显著,而在板块离散边界无明显变化趋势;西南印度洋中脊、大西洋中脊、中印度洋中脊等地区重力异常垂直梯度变化显著,且在西太平洋俯冲带、部分海岭区域也存在明显变化,其空间分布与地形基本吻合.海洋重力场变化整体上准确反映了全球洋底板块构造运动.相较于重力异常变化反演结果,重力垂直梯度的变化能够更为准确地反映洋底板块运动特征,特别是在洋中脊区域,扩张速率越小,垂直重力梯度变化越显著.此外,详细讨论了测高海洋重力场不确定因素对洋底板块运动分析结果的影响,海面坡度改正是主要因素之一.

关键词：卫星测高测高重力场重力场变化板块运动垂直重力梯度

Multichannel singular spectrum analysis of the axial atmospheric angular momentum

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Geodesy and Geodynamics 2017年第6期8卷 433-442页

作者： Leonid Zotov N.S.Sidorenkov ch.Bizouard c.k.shum Wenbin Shen National Research University Higher School of Economics Moscow Institute of Electronics and MathematicsRussia Hydro-Meteorological center of Russia Global Atmospheric Circulation LaboratoryRussia SYRTE Observatoire de ParisPSL Research UniversityCNRSSorbonne Universit esUPMC Univ.Paris 06Franced Division of Geodetic Science School of Earth SciencesThe Ohio State UniversityUSA Institute of Geodesy&Geophysics Chinese Academy of SciencesWuhanChina department of geophysics school of geodesy and ceomaticskey Laboratory of Geospace Environment and Geodesy of MinistryWuhan UniversityWuhan 430079China

Earth＇s variable rotation is mainly produced by the variability of the AAM（atmospheric angular momentum）. In particular, the axial AAM component X_3, which undergoes especially strong variations,induces changes in the Earth＇s rotation rate. In this study we analysed maps of regional input into the effective axial AAM from 1948 through 2011 from NcEP/NcAR reanalysis. Global zonal circulation patterns related to the LOD（length of day） were described. We applied MSSA（Multichannel Singular Spectrum Analysis） jointly to the mass and motion components of AAM, which allowed us to extract annual, semiannual, 4-mo nth, quasi-biennial, 5-year, and low-frequency oscillations. Pcs（Principal components） strongly related to ENSO（El Nino southern oscillation） were released. They can be used to study ENSO-induced changes in pressure and wind fields and their coupling to LOD. The Pcs describing the trends have captured slow atmospheric circulation changes possibly related to climate variability.

关键词： Earth's variable rotation Atmospheric circulation AAM(Atmospheric angular momentum) MSSA(Multichannel singular spectrum analysis) ENSO(El Nino southern oscillation) LOD(Length of day)

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精密定轨用地球大气模型误差的补偿方法

天文学报 1997年第3期38卷 303-311页

作者：汤锡生 c.k.shum 北京航天指挥控制中心北京100101 centerforSpaceResearchUniversityofTexasatAustin

本文提出了一种用于精密轨道确定的地球大气模型误差的补偿方法，这种方法采用改进大气周日峰角的技术，有效地补偿了大气密度模型的误差，并具有较好的物理意义．与传统的每圈改进一次加速度的方法比较，轨道确定达到了相当的径向精... 详细信息

本文提出了一种用于精密轨道确定的地球大气模型误差的补偿方法，这种方法采用改进大气周日峰角的技术，有效地补偿了大气密度模型的误差，并具有较好的物理意义．与传统的每圈改进一次加速度的方法比较，轨道确定达到了相当的径向精度，且避免了轨道改进参数间的相关性，同时解算参数的数量也少了一半．

关键词：精密定轨大气模型误差补偿法卫星轨道

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在非球形引力摄动下金星轨道器运动的分析解

中国科学（A辑） 1999年第10期29卷 952-960页

作者：刘林 c.k.shum 南京大学天文系南京210093 TheTexasUniversityatAustincenterforSpaceResearch

给出了行星轨道器在慢自转中心天体 (如金星、水星等 )非球形引力摄动下运动的分析摄动解 ,它适用于 0

关键词：中心天体金星轨道器非球形引力位分析摄动解

Space Geodetic Variables and contributions from the Oceans

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Space Geodetic Variables and Contributions from the Oceans