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On the Accuracy Assessment of the Latest Releases of GOCE Satellite-Based Geopotential Models with EGM2008 and Terrestrial GPS/Levelling and Gravity data over Egypt

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International Journal of Geosciences 2016年第11期7卷 1323-1344页

作者： Mohamed El-Ashquer Basem Elsaka Gamal El-Fiky Construction Engineering and Utilities Department Faculty of Engineering Zagazig University Zagazig Egypt National research Institute of Astronomy and Geophysics (NRIAG) Helwan Cairo Egypt Institute of Geodesy and geoinformation University of Bonn Bonn Germany

The Global Geopotential Models (GGMs) of GOCE (Gravity Recovery and steady- state Ocean Circulation Explorer) differ globally as well as regionally in their accuracy and resolution based on the maximum degree and order (d/o) of the fully normalized spherical harmonic (SH) coefficients, which express each GGM. The main idea of this study is to compare the free-air gravity anomalies and quasi geoid heights determined from several recent GOCE-based GGMs with the corresponding ones from the Earth Gravitational Model 2008 (EGM2008) over Egypt on the one hand and with ground-based measurements on the other hand. The results regarding to the comparison of GOCE-based GGMs with terrestrial gravity and GPS/levelling data provide better improvement with respect to EGM2008. The 4th release GOCE-based GGM developed with the use of space-wise solution strategy (SPW_R4) approximates the gravity field well over the Egyptian region. The SPW_R4 model is accordingly suggested as a reference model for recovering the long wavelength (up to SH d/o 200) components of quasi geoid heights when modelling the gravimetric quasi-geoid over the Egypt. Finally, three types of transformation models: Four-, Five- and Seven-parameter transformations have been applied to reduce the data biases and to provide a better fitting of quasi geoid heights obtained from the studied GOCE-based GGMs to those from GPS/levelling data. These models reveal that the standard deviation of vertical datum over Egypt is at the level of about 32 cm.

关键词： GOCE-Based GGMs Free-Air Gravity Anomalies GPS/Levelling data Spectral Enhancement Method (SEM)

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Maintenance of Millimeter-level Geodetic Reference Framework

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测绘学报:英文版 2023年第3期6卷 9-18页

作者： Yamin DANG Hu WANG Fuping SUN Guangwei JIANG Xinhui ZHU Yingyan CHENG Qiang YANG Yingying REN Jing JIAO Chinese Academy of Surveying and Mapping Beijing 100036China Institute of Geospatial Information Information Engi-neering UniversityZhengzhou 450052China Geodetic data Processing Centre of Ministry of Natural Resources Xi’an 710054China College of Surveying and Geo-Informatics Tongji UniversityShanghai 200092China

The high-precision terrestrial reference frame,as the spatial benchmark for geodesy,is an important national ***,due to the influence of nonlinear factors related to geophysical phenomena,the overall maintenance accuracy of the ITRF framework is still at the centimeter ***,accurately characterizing the true trajectories of linear motion,nonlinear motion,and geocentric motion of the reference station is the key to achieve the construction and maintenance technology of a millimeter level terrestrial reference *** on long-term global and regional GNSS observation data,more Chinese geodesy scientists devoted much efforts to the maintenance of millimeter-level geodetic reference *** main contributions of this work included the followings:①Dynamic maintenance of millimeter-level terrestrial reference frame;②research progress on the method of maintenance of regional reference frame based on GNSS;③The progress of CGCS2000 frame maintenance in millimeter level accuracy;④Reprocessing and reanalysis of two-decade GNSS observation in continental China;⑤research on current GNSS velocity field model and deformation in Chinese mainland;⑥The preliminary realization and evaluation of CTRF2020.

关键词： reference framework millimeter level dynamic maintenance repro3 BDS3 CTRF2020

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Insight into Urban Faults by Wavelet Multi-Scale Analysis and Modeling of Gravity data in Shenzhen,China

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Journal of Earth Science 2018年第6期29卷 1340-1348页

作者： Chuang Xu Haihong Wang Zhicai Luo Hualiang Liu Xiangdong Liu MOE Key laboratory of Fundamental Physical Quantities Measurement School of PhysicsHuazhong University of Science and Technology School of Geodesy and Geomatics Wuhan University Key laboratory of Geospace Environment and Geodesy Ministry of EducationWuhan University China Water Resources Beifang Investigation Design and Research Co.Ltd.

Urban faults in Shenzhen are potential threats to city security and sustainable development. In consideration of the importance of the Shenzhen fault zone, the author provide a detailed interpretation on gravity data model. Bouguer gravity covering the whole Shenzhen City was calculated with a 1-km resolution. Wavelet multi-scale analysis（MSA） was applied to the Bouguer gravity data to obtain the multilayer residual anomalies corresponding to different depths. In addition, 2D gravity models were constructed along three profiles. The Bouguer gravity anomaly shows an NE-striking high-low-high pattern from northwest to southeast, strongly related to the main faults. According to the results of MSA, the correlation between gravity anomaly and faults is particularly significant from 4 to 12 km depth. The residual gravity with small amplitude in each layer indicates weak tectonic activity in the crust. In the upper layers, positive anomalies along most of faults reveal the upwelling of high-density materials during the past tectonic movements. The multilayer residual anomalies also yield important information about the faults, such as the vertical extension and the dip direction. The maximum depth of the faults is about 20 km. In general, NE-striking faults extend deeper than NW-striking faults and have a larger dip angle.

关键词： urban faults Bouguer gravity anomaly wavelet multi-scale analysis gravity modeling Shenzhen

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Bathymetry predicting using the altimetry gravity anomalies in South China Sea

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Geodesy and Geodynamics 2018年第2期9卷 156-161页

作者： Zhongmiao Sun Mingda Ouyang Bin Guan Stake Key laboratory of Geo-information Engineering Xi'an research Institute of Surveying and Mapping Xi'an Division of Surveying and Mapping

In South China Sea(112°E-119°E, 12°N-20°N), 81159 ship soundings published by NGDC(National Geophysics data Center) and the altimetry gravity anomalies published by SIO(Scripps Institute of Oceanography) were used to predict bathymetry by GGM(gravity-geologic method) and SAS(Smith and Sandwell) method respectively. The residual 40576 ship soundings were used to estimate precisions of the predicted bathymetry models. Results showed that: the standard deviation of difference between the GGM model and ship soundings was 59.75 m and the relative accuracy was 1.86%. The SAS model is60.07 m and 1.87%. The power spectral densities of the ETOPO1, SIO, GGM and SAS models were also compared and analyzed. At last, we presented an integrated bathymetry model by weighted averaging method, the weighted factors were determined by precisions of the ETOPO1, SIO, GGM, and SAS model respectively.

关键词： Gravity-geologic method Smith and Sandwell method Bathymetry Gravity anomaly Power spectral density analysis

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Exploring nationally and regionally defined models for large area population mapping

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International Journal of Digital Earth 2015年第12期8卷 989-1006页

作者： A.E.Gaughan F.R.Stevens C.Linard N.N.Patel A.J.Tatem Department of Geography and Geosciences University of LouisvilleLouisvilleKYUSA Biological Control and Spatial Ecology UniversitéLibre de BruxellesBrusselsBelgium Department of Geography and geoinformation Science George Mason UniversityFairfaxVAUSA Department of Geography and Environment University of SouthamptonSouthamptonUK Fogarty International Center National Institutes of HealthBethesdaMDUSA Flowminder Foundation StockholmSweden

Interactions between humans,diseases,and the environment take place across a range of temporal and spatial scales,making accurate,contemporary data on human population distributions critical for a variety of *** for disaggregating census data to finer-scale,gridded population density estimates continue to be refined as computational power increases and more detailed census,input,and validation datasets become ***,the availability of spatially detailed census data still varies widely by *** this study,we develop quantitative guidelines for choosing regionally-parameterized census count disaggregation models over country-specific *** examine underlying methodological considerations for improving gridded population datasets for countries with coarser scale census data by investigating regional versus country-specific models used to estimate density surfaces for redistributing census *** is given to the spatial resolution of input census data using examples from East Africa and Southeast *** suggest that for many countries more accurate population maps can be produced by using regionally-parameterized models where more spatially refined data exists than that which is available for the focal *** study highlights the advancement of statistical toolsets and considerations for underlying data used in generating widely used gridded population data.

关键词： human population modeling random forest regression dasymetric mapping gridded population datasets

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The Extent and Effectiveness of Protected Areas in the Russian Federation

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Journal of Geodesy and geoinformation Science 2022年第2期5卷 75-84页

作者： Kseniia SERGEEVA Hui LIN School of Geography and Environment/UNESCO HIST-NB Jiangxi Normal UniversityNanchang 330022China Key laboratory of Poyang Lake Wetland and Watershed research Ministry of Education Nanchang 330022China

To tackle environmental challenges and in particular,the problems associated with the high demand for forests and resources,the consequence of which is the degradation of ecological systems,Russia has developed the biggest network of specially protected natural areas in the *** the scale of SPNA may look impressive,a recent comprehensive study of the period from 2001 to 2018 brought the spotlight on protected areas in Russia experiencing significant tree loss *** Russia is confronting unprecedented fires that break records every year,the problem of preserving rare animal and plant species,their habitats,and natural ecosystems is *** paper is intended to assess the extent and effectiveness of SPNAs with regard to wilderness conservation in the Russian Federation based on the latest data;the main focus being on the period of 2014—2019,before and after the launch of the environmental safety strategies,along with additional analysis of available data for the following year of *** due consideration of unique geographical,economic,and socio-cultural circumstances,as well as historical background and legislative reality of SPNAs in Russia,we have conducted a statistical analysis of data from the official annual reports from the Federal State Statistics Service on SPNAs by territories and significance,expenditures on maintenance and ecotourism,followed by RGB analysis of satellite imagery via means of GIS software for visualization of obtained data and further *** the growth of the SPNA network in Russia,resulting in an astonishing 2402 Mha in 2020,an estimated 4 Mha of tree loss accounted for SPNAs over the period of 2014—2019,and 134 Mha in 2020 *** findings indicate a need for the application of a comprehensive GIS approach for further development and effective management of the SPNA network in ***,the results include recommendations on legislative changes,engagement of locals in SPNA protection,and po

关键词： GIS remote sensing protected area SPNA nature conservation deforestation tree loss

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The diurnal and seasonal characteristics of urban heat island variation in Beijing city and surrounding areas and impact factors based on remote sensing satellite data

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Science China Earth Sciences 2005年第Z2期48卷 220-229页

作者： ZHANG Jiahua, HOU Yingyu, LI Guicai, YAN Hao YANG Limin & YAO Fengmei The Chinese Academy of Meteorological Sciences, Beijing 100081, China The National Meteorological Center, Beijing 100081, China The National Satellite Meteorological Center, Beijing 100081, China Joint laboratory for geoinformation Science, The Chinese University of Hong Kong, Hong Kong, China Department of Geosciences, Graduate School of Chinese Academy of Sciences, Beijing 100039, China The Chinese Academy of Meteorological Sciences Beijing 100081 China The National Meteorological Center Beijing 100081 China The National Satellite Meteorological Center Beijing 100081 China Joint laboratory for geoinformation Science The Chinese University of Hong Kong Hong Kong China

Based on the land surface temperature (LST), the land cover classification map,vegetation coverage, and surface evapotranspiration derived from EOS-MODIS satellite data, and by the use of GIS spatial analytic technique and multivariate statistical analysis method, the urban heat island (UHI) spatial distribution of the diurnal and seasonal variabilities and its driving forces are studied in Beijing city and surrounding areas in 2001. The relationships among UHI distribution and landcover categories, topographic factor, vegetation greenness, and surface evapotranspiration are analyzed. The results indicate that: (i) The significant UHI occur in Beijing city areas in the four seasons due to high heat capacity and multi-reflection of compression building, as well as with special topographic features of its three sides surrounded by mountains,especially in the summer. The UHI spatial distribution is corresponding with the urban geometry structure profile. The LST difference is approximately 4-6℃ between Beijing city and suburb areas, comparatively is 8- 10℃ between Beijing city area and outer suburb area in northwestern regions. (ii) The UHI distribution and intensity in daytime are different from nighttime in Beijing city area, the nighttime UHI is obvious. However, in the daytime, the significant UHI mainly appears in the summer, the autumn takes second place, and the UHI in the winter and the spring seem not obvious. The surface evapotranspiration in suburb areas is larger than that in urban areas in the summer, and high latent heat exchange is evident, which leads to LST difference between city area and suburb area. (iii) The reflection of surface landcover categories is sensitive to the UHI, the correlation between vegetation greenness and UHI shows obviously *** scatterplot shows that there is the negative correlation between NDVI and LST (R2 = 0.6481).The results demonstrate that the vegetation greenness is an important factor for reducing the UHI,and la

关键词： urban heat island, vegetation cover, LST, MODIS, Beijing city and surrounding areas.

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Regional Evaluation of GOCE-Based GGMs with Ground-Based Gravity and GPS/Levelling data over Egypt

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International Journal of Geosciences 2019年第6期10卷 652-668页

作者： Ahmed Saadon Basem Elsaka Mohamed El-Ashquer Gamal El-Fiky Construction Engineering and Utilities Department Faculty of Engineering Zagazig University Zagazig Egypt National research Institute of Astronomy and Geophysics (NRIAG) Cairo Egypt Institute of Geodesy and geoinformation University of Bonn Bonn Germany The Bilbies Higher Institute of Engineering Bilbies Egypt

The gravity field and steady-state ocean circulation explorer (GOCE) satellite mission has provided numerous Global Geopotential Models (GGMs) with different processing methodologies and model accuracies. In the current contribution, the latest releases of GOCE-based GGMs are evaluated on the regional scale using the available terrestrial GPS/Levelling and gravity data collected over Egypt. To overcome the spectral inconsistency between the GOCE-based GGMs and the ground-based data, the spectral enhancement method (SEM) is applied. Five of GOCE-based GGMs have been used, namely GOSG01S, IGGT_R1, IfE_GOCE05s_ GO_CONS_GCF_2_SPW_R5 (SPW_R5 in the following) and NULP-02. The evaluation process of GOCE-based GGMs with the available ground data over Egypt considering the SEM method shows remarkable improvements obtained from the SPW_R5 model. The model provides lower differences of the standard deviations with respect to the EGM2008 and the other applied geopotential gravity models as well as the applied ground-based gravity and GPS/Levelling data. The findings regarding the ground-based data show obvious reductions of about 15.16% and 32.22% achieved by the GOCE-based model in term of standard deviations differences of gravity anomalies and geoid heights, respectively. Therefore, the SPW_R5 model is recommended to be applied as a reference model for compensating the long-to-short wavelength (up to spherical harmonics degree/order 280) components when modelling the gravimetric geoid over Egypt.

关键词： GOCE-Based GGMs Gravity Anomalies GNSS/Levelling Spectral Enhancement Method (SEM)

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An Adaptive and Image-guided Fusion for Stereo Satellite Image Derived Digital Surface Models

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Journal of Geodesy and geoinformation Science 2022年第4期5卷 1-9页

作者： Hessah ALBANWAN Rongjun QIN Department of Civil Engineering Kuwait UniversityKuwait 72504Kuwait Geospatial data Analytics Lab The Ohio State UniversityColumbus 43210USA Department of Civil Environmental and Geodetic EngineeringThe Ohio State UniversityColumbus 43210USA Department of Electrical and Computer Engineering The Ohio State UniversityColumbus 43210USA Translational data Analytics Institute The Ohio State UniversityColumbus 43210USA

The accuracy of Digital Surface Models(DSMs)generated using stereo matching methods varies due to the varying acquisition conditions and configuration parameters of stereo *** has been a good practice to fuse these DSMs generated from various stereo pairs to achieve enhanced,in which multiple DSMs are combined through computational approaches into a single,more accurate,and complete ***,accurately characterizing detailed objects and their boundaries still present a challenge since most boundary-ware fusion methods still struggle to achieve sharpened depth discontinuities due to the averaging effects of different ***,we propose a simple and efficient adaptive image-guided DSM fusion method that applies k-means clustering on small patches of the orthophoto to guide the pixel-level fusion adapted to the most consistent and relevant elevation *** experiment results show that our proposed method has outperformed comparing methods in accuracy and the ability to preserve sharpened depth edges.

关键词： Digital Surface Model(DSM) DSM Fusion adaptive fusion satellite stereo images

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A spatiotemporal data collection of viral cases for COVID-19 rapid response

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big Earth data 2021年第1期5卷 90-111页

作者： Dexuan Sha Yi Liu Qian Liu Yun Li Yifei Tian Fayez Beaini Cheng Zhong Tao Hu Zifu Wang Hai Lan You Zhou Zhiran Zhang Chaowei Yang NSF Spatiotemporal Innovation Center George Mason UniversityFairfaxVAUSA Department of Geography and geoinformation Science George Mason UniversityFairfaxVAUSA Department of Aerospace and Mechanical Engineering University of Notre DameNotre DameINUSA Center for Geographic Analysis Harvard UniversityCambridgeMAUSA School of Resource and Environmental Sciences Wuhan UniversityWuhanHubeiChina

Under the global health crisis of COVID-19,timely,and accurate epi-demic data are important for observation,monitoring,analyzing,modeling,predicting,and mitigating *** case data can be jointly analyzed with relevant factors for various applications in the context of the *** COVID-19 case data are scattered across a variety of data sources which may consist of low data quality accompanied by inconsistent data *** address this short-coming,a multi-scale spatiotemporal data product is proposed as a public repository platform,based on a spatiotemporal cube,and allows the integration of different data sources by adopting various data *** the spatiotemporal cube,a comprehensive data processing workflow gathers disparate COVID-19 epidemic data-sets at the global,national,provincial/state,county,and city *** proposed framework is supported by an automatic update with a 2-h frequency and the crowdsourcing validation team to produce and update data on a daily time *** rapid-response dataset allows the integration of other relevant socio-economic and environ-mental factors for spatiotemporal *** data is available in Harvard dataverse platform(https://***/***?persistentId=doi:10.7910/DVN/8HGECN)and GitHub open source repository(https://***/stccenter/COVID-19-data).

关键词： COVID-19 pandemic public health semi-automatic validation spatiotemporal data set

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