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Evaluating the weekly changes in terrestrial water storage estimated by two different inversion strategies in the Amazon River Basin

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Geodesy and Geodynamics 2023年第6期14卷 614-626页

作者： Bo Zhong Xianpao Li Qiong Li Jiangtao Tan Xianyun Dai School of Geodesy and Geomatics Hubei Luojia LaboratoryWuhan UniversityWuhan 430079China Key laboratory of Geospace Environment and Geodesy Ministry of EducationWuhan UniversityWuhan 430079China School of Civil Engineering and Geomatics Southwest Petroleum UniversityChengdu 610500China

In this study,we estimated the weekly Gravity Recovery and Climate Experiment(GRACE)spherical harmonic(SH)solutions and regional mascon solutions using GRACE-based Geopotential Difference(GPD)data and investigated their abilities in retrieving terrestrial water storage(TWS)changes over the Amazon River Basin(ARB)from January 2003 to February *** performance of the weekly GPD-SH and GPDmascon solutions was evaluated by comparing them with the weekly GFZ-SH solutions,Global Land Data Assimilation Systems(GLDAS)-NOAH hydrological model outputs,and monthly GFZ-SH,GPD-SH,and CSRmascon solutions in the spatio-temporal and spectral *** results demonstrate that the weekly GPD-SH and GPD-mascon present good consistency with the weekly GFZ-SH solutions and GLDAS-NOAH estimates in the spatio-temporal domains,but GPD-mascon presents stronger signal amplitudes and more spatial *** comparison of the monthly average of weekly estimates and monthly solutions demonstrates that the weekly GPD-mascon and GFZ-SH with DDK1 filtering are close to the monthly CSRmascon and GFZ-SH solutions,***,the signal amplitudes of TWS changes from GPD-SH and GFZ-SH with 650 km Gaussian filtering are smaller than the monthly solutions,and the corresponding Root Mean Square Errors between the TWS change time series from the monthly average of weekly solutions and monthly estimates are 18.12 mm(GPD-mascon),18.81 mm(GFZ-SH-DDK1),24.93 mm(GPDSH-G650km),and 33.07 mm(GFZ-SH-G650km),***,the TWS change time series derived from weekly solutions present more high-frequency time-varying information than monthly ***,the 300 km Gaussian filtering can improve the signal amplitudes of TWS changes from the weekly GPD-SH solutions more than those with 650 km Gaussian filtering,but the corresponding noise level is *** weekly GPD-SH and GPD-mascon solutions can extend the application scopes of GRACE and provide good complements to the cu

关键词： Terrestrial water storage change Amazon River Basin GRACE-based geopotential differences Weekly solutions Performance evaluation

Multipath tracking with LTE signals for accurate TOA estimation in the application of indoor positioning

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Geo-Spatial Information Science 2023年第1期26卷 31-43页

作者： Zhaoliang Liu Liang Chen Xin Zhou Nan Shen Ruizhi Chen The State Key laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina

Indoor positioning with high accuracy plays an important role in different application *** a widely used mobile communication signal,the Long-Term Evolution(LTE)network can be well received in indoor and outdoor *** article studies a method of using different reference signals in the LTE downlink for carrier phase time of arrival(TOA)***,a solution is proposed and a multipath tracking Software Defined Receiver(SDR)is developed for indoor *** our SDR indoor positioning system,the pilot signals of the LTE signals are firstly obtained by the coarse synchronization and ***,with the assistance of the pilot signals,the time delay acquisition,the multipath estimating delay lock loop(MEDLL)algorithm,and the multipath anomaly detection are sequentially carried out to obtain navigation observations of received ***,to compare the perfor-mance of different pilot signals,the Secondary Synchronous Signals(SSS)and Cell Reference Signals(CRS)are used as pilot signals for carrier phase-based TOA estimation,***,to quantify the accuracy of our multipath tracking SDR,indoor field tests are carried out in a conference environment,where an LTE base station is installed for commercial *** test results based on CRS show that,in the static test scenarios,the TOA accuracy measured by the 1-σerror interval is about 0.5 m,while in the mobile environment,the probability of range accuracy within 1.0 m is 95%.

关键词： Long-Term Evolution(LTE) indoor positioning multipath estimation delay locked loop(MEDLL) carrier phase time of arrival(TOA)

Revisiting the period and quality factor of the Chandler wobble and its possible geomagnetic jerk excitation

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Geodesy and Geodynamics 2022年第5期13卷 427-434页

作者： Yachong An Hao Ding Department of Geophysics School of Geodesy and GeomaticsKey Laboratory of Geospace Environment and Geodesy of the Ministry of EducationWuhan University430079 WuhanChina hubei Luo Jia laboratory 430079 WuhanChina

The period and quality factor of the Chandler wobble(CW)are useful for constraining the Earth’s internal structure properties,such as the mantle *** has been shown that the CW is mainly excited by a combination of atmospheric and oceanic processes;hence based on a deconvolution method,we can remove them from the excitation sequence of the CW to estimate its period P and quality factor *** finally re-estimate P=432.3±0.8 days and Q=85±15 for the *** on those two estimates,we investigate the relationship between the geomagnetic jerks and the excitation sequences of the *** geomagnetic jerks or jerk bounds are well consistent with the sudden changes of the excitation sequences of the *** demonstrates that the geomagnetic jerks could be a possible excitation source of the *** is crucial for understanding the excitation of the CW and for deeper geophysical insights into the geomagnetic jerks.

关键词： Chandler wobble Quality factor De-convolution Geomagnetic jerks

luojiaAI:A cloud-based artificial intelligence platform for remote sensing image interpretation

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Geo-Spatial Information Science 2023年第2期26卷 218-241页

作者： Zhan Zhang Mi Zhang Jianya Gong Xiangyun Hu Hanjiang Xiong Huan Zhou Zhipeng Cao State Key laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina School of Remote Sensing and Information Engineering Wuhan UniversityWuhanChina Department of Land-Surveying and Geo-Informatics Hong Kong Polytechnic UniversityHong KongChina

The rapid processing,analysis,and mining of remote-sensing big data based on intelligent interpretation technology using remote-sensing cloud computing platforms(RS-CCPs)have recently become a new *** existing RS-CCPs mainly focus on developing and optimizing high-performance data storage and intelligent computing for common visual representation,which ignores remote sensing data characteristics such as large image size,large-scale change,multiple data channels,and geographic knowledge embedding,thus impairing computational efficiency and *** construct a luojiaAI platform composed of a standard large-scale sample database(luojiaSET)and a dedicated deep learning framework(luojiaNET)to achieve state-of-the-art performance on five typical remote sensing interpretation tasks,including scene classification,object detection,land-use classification,change detection,and multi-view 3D *** details of the luojiaAI application experiment can be found at the white paper for luojiaAI industrial *** addition,luojiaAI is an open-source RS-CCP that supports the latest Open Geospatial Consortium(OGC)standards for better developing and sharing Earth Artificial Intelligence(AI)algorithms and products on benchmark *** narrows the gap between the sample database and deep learning frameworks through a user-friendly data-framework collaboration mechanism,showing great potential in high-precision remote sensing mapping applications.

关键词： Artificial intelligence cloud computing platform remote-sensing intelligent interpretation sample database deep learning framework

A newly unraveled 13.6-year oscillation from GPS displacements and its potential implications for the dynamic reference frame

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Science China Earth Sciences 2024年第10期67卷 3204-3212页

作者： Hao DING Weiping JIANG School of Geodesy and Geomatics Hubei Luojia LaboratoryWuhan UniversityWuhan 430079China GNSS Research Center Wuhan UniversityWuhan 430079China

Numerous practical geodetic and geophysical applications necessitate precise measurements of GNSS displacements at the millimeter or sub-millimeter level. To attain such precision, it is imperative to identify and analyze the unidentified decadal signals inherent in the GPS displacements. In this research, we employ the optimal sequence estimation method to effectively detect an about 13.6-year oscillational signal with an excited amplitude of 3.6±1.2 mm in the U-components of the GPS displacements. It is noteworthy that this signal demonstrates a consistent spatial pattern characterized by the spherical harmonic Y_(2,-2). We conduct a comparative analysis with the 13.6-year oscillation observed in length-of-day variations(and geomagnetic records), finding that they are in reverse phase. After eliminating the Earth's external excitation sources through the utilization of two distinct in-situ hydrological records, we suggest that the 13.6-year GPS signal may come from the internal motions within the Earth. However, the specific excitation source and the detailed physical mechanism remain uncertain. Additionally, we develop a mathematical displacement model to explain the 13.6-year signal. Our findings indicate that this signal can result in displacements of up to 1.37 mm and velocity effects of 0.63 mm/yr(for U-component) at maximum. These results underscore the necessity of incorporating this 13.6-year signal into the construction and maintenance of a dynamic reference frame at the millimeter level.

关键词： GPS displacements Decadal changes 13.6-year oscillation Displacement model Dynamic reference frame

Suitable region of dynamic optimal interpolation for efficiently altimetry sea surface height mapping

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Geodesy and Geodynamics 2024年第2期15卷 142-149页

作者： Jiasheng Shi Taoyong Jin School of Geodesy and Geomatics Hubei Luojia LaboratoryWuhan UniversityWuhan 430079China MOE Key laboratory of Geospace Environment and Geodesy Wuhan UniversityWuhan 430079China

The dynamic optimal interpolation(DOI)method is a technique based on quasi-geostrophic dynamics for merging multi-satellite altimeter along-track observations to generate gridded absolute dynamic topography(ADT).Compared with the linear optimal interpolation(LOI)method,the DOI method can improve the accuracy of gridded ADT locally but with low computational ***,considering both computational efficiency and accuracy,the DOI method is more suitable to be used only for regional *** this study,we propose to evaluate the suitable region for applying the DOI method based on the correlation between the absolute value of the Jacobian operator of the geostrophic stream function and the improvement achieved by the DOI *** verifying the LOI and DOI methods,the suitable region was investigated in three typical areas:the Gulf Stream(25°N-50°N,55°W-80°W),the Japanese Kuroshio(25°N-45°N,135°E-155°E),and the South China Sea(5°N-25°N,100°E-125°E).We propose to use the DOI method only in regions outside the equatorial region and where the absolute value of the Jacobian operator of the geostrophic stream function is higher than1×10^(-11).

关键词： Dynamic optimal interpolation Linearoptimal interpolation Satellite altimetry Sea surface height Suitable region

A Data-driven Method for Realistic Covariance Prediction of Space Object with Sparse Tracking Data

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Research in Astronomy and Astrophysics 2023年第8期23卷 220-237页

作者： Hong-Kang Liu Bin Li Yan Zhang Ji-Zhang Sang School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China hubei luojia laboratory Wuhan 430079China Xi'an Satellite Control Center Xi'an 710043China

Covariance of the orbital state of a resident space object(RSO)is a necessary requirement for various space situational awareness tasks,like the space collision *** describes an accuracy envelope of the RSO's ***,in current space surveillance,the tracking data of an individual RSO is often found insufficiently accurate and sparsely distributed,making the predicted covariance(PC)derived from the tracking data and classical orbit dynamic system usually unrealistic in describing the error characterization of orbit *** the fact that the tracking data of an RSO from a single station or a fixed network share a similar temporal and spatial distribution,the evolution of PC could share a hidden relationship with that data *** study proposes a novel method to generate accurate PC by combining the classical covariance propagation method and the data-driven *** popular machine learning algorithms are applied to model the inconsistency between the orbit prediction error and the PC from historical observations,and then this inconsistency model is used for the future *** results with the Swarm constellation satellites demonstrate that the trained Random Forest models can capture more than 95%of the underlying inconsistency in a tracking scenario of sparse *** importantly,the trained models show great generalization capability in correcting the PC of future epochs and other RSOs with similar orbit characteristics and observation ***,a deep analysis of generalization performance is carried out to describe the temporal and spatial similarities of two data sets,in which the Jaccard similarity is *** demonstrates that the higher the Jaccard similarity is,the better the generalization performance will be,which may be used as a guide to whether to apply the trained models of a satellite to other ***,the generalization performance is also evaluated by the classical Cramer v

关键词： celestial mechanics-methods analytical-miscellaneous

Constraint on the focal mechanism of the 2011 Tohoku earthquake from the radial modes

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Geodesy and Geodynamics 2024年第1期15卷 27-32页

作者： Weikun Chen Hao Ding School of Geodesy and Geomatics Hubei LuoJia LaboratoryWuhan UniversityWuhan 430079China

Different from other normal modes of the Earth’s free oscillation that depend on all the six components(M_(rr),M_(tt),M_(pp),M_(rt),M_(rp),and M_(tp))of the centroid moment tensor,the amplitudes of the radial modes depend on the M_(rr)component(e.g.,scalar moment(M_(0)),dip(δ),and slip(λ))and hypocenter depth of the focal mechanism,and hence can be easily used to constrain these parameters of the focal *** this study,we use the superconducting gravimeter(SG)records after the 2011 Tohoku earthquake to analyze the radial modes_(0)S_(0)and_(1)S_(0).Based on the solutions of the focal mechanism provided by the GCMT and USGS,we can obtain the theoretical amplitudes of these two radial *** the theoretical amplitudes with the observation amplitudes,it is found that there are obvious differences between the former and the latter,which means that the GCMT and USGS focal mechanisms cannot well represent the real focal mechanism of the 2011 *** the GCMT solution as a reference and changing the depth and the three parameters of the M_(rr)moment,the scalar moment(M_(0))and the dip(δ)have significant influences,but the effects of the slip(λ)and the depth are *** comparisons,we provide a new constraint(M_(0)=5.8±0.09×10^(22)N·m,δ=10.1±0.08°,λ=88°,and depth=20 km)for the focal mechanism of the 2011 *** addition,we further determine the center frequency(1.631567±2.6e^(-6)mHz)and quality factor(2046.4±50.1)of the_(1)S_(0)mode.

关键词： Focal mechanism Radial modes Gravity observation

luojia-HSSR:A high spatial-spectral resolution remote sensing dataset for land-cover classification with a new 3D-HRNet

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Geo-Spatial Information Science 2023年第3期26卷 289-301页

作者： Yue Xu Jianya Gong Xin Huang Xiangyun Hu Jiayi Li Qiang Li Min Peng School of Remote Sensing and Information Engineering Wuhan UniversityWuhanChina State Key laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina hubei luojia laboratory WuhanChina Institute of Artificial Intelligence in Geomatics Wuhan UniversityWuhanChina Data Center Shenyang Surveying and Mapping Institute Co.LtdShenyangChina

High Spatial and Spectral Resolution(HSSR)remote-sensing images can provide rich spectral bands and detailed ground information,but there is a relative lack of research on this new type of remote-sensing *** there are already some HSSR datasets for deep learning model training and testing,the data volume of these datasets is small,resulting in low classification accuracy and weak generalization ability of the trained *** this paper,an HSSR dataset luojia-HSSR is constructed based on aerial hyperspectral imagery of southern Shenyang City of Liaoning Province in *** our knowledge,it is the largest HSSR dataset to date,with 6438 pairs of 256×256 sized samples(including 3480 pairs in the training set,2209 pairs in the test set,and 749 pairs in the validation set),covering area of 161 km2 with spatial resolution 0.75 m,249 Visible and Near-Infrared(VNIR)spectral bands,and corresponding to 23 classes of field-validated ground *** is an ideal experimental data for spatial-spectral feature ***,a new deep learning model 3D-HRNet for interpreting HSSR images is *** conv-neck in HRNet is modified to better mine the spatial information of the ***,a 3D convolution module with attention mechanism is designed to capture the global-local fine spectral information ***,the 3D convolution is inserted into the HRNet to optimize the *** experiments show that the 3D-HRNet model has good interpreting ability for the luojia-HSSR dataset with the Frequency Weighted Intersection over Union(FWIoU)reaching 80.54%,indicating that the luojia-HSSR dataset constructed in this paper and the proposed 3D-HRnet model have good applicable prospects for processing HSSR remote sensing images.

关键词： High Spatial and Spectral Resolution(HSSR) remotesensing image classification deep learning Convolutional Neural Network(CNN)