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An elevation change dataset in Greenland ice sheet from 2003 to 2020 using satellite altimetry data

Big Earth Data 2024年第2期8卷 231-248页

作者： Bojin Yang Shuang Liang Huabing Huang Xinwu Li Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijingChina International Research Center of Big Data for Sustainable Development Goals BeijingChina University of Chinese Academy of Sciences BeijingChina School of Geospatial Engineering and Science Sun Yat-Sen UniversityGuangzhouChina Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) ZhuhaiChina

ABSTRACT A decade-long pronounced increase in temperatures in the Arctic resulted in a global warming hotspot over the Greenland ice sheet(GrIS).Associated changes in the cryosphere were the consequence and led to a demand for monitoring glacier changes,which are one of the major parameters to analyze the responses of the GrIS to climate ***-term altimetry data(***,CryoSat-2,and ICESat-2)can provide elevation changes over different periods,and many methods have been developed for altimetry alone to obtain elevation *** this work,we provided the long-term elevation change rate data of the GrIS in three different periods using ICESat data(from February 2003 to October 2009),Cryosat-2 data(from August 2010 to October 2018)and ICESat-2 data(from October 2018 to December 2020).Optimal methods were applied to the datasets collected by three different altimeters:crossover analysis for ICESat/ICESat-2 and the surface fit method for *** data revealed that the elevation change rates of the GrIS were-12.19±3.81 cm/yr,-19.70±3.61 cm/yr and-23.39±3.06 cm/yr in the three different periods,corresponding to volume change rates of-210.20±25.34 km^(3)/yr,-339.11±24.01 km^(3)/yr and-363.33±20.37 km^(3)/yr,*** general,the obtained results agree with the trends discovered by other studies that were also derived from satellite altimetry *** dataset provides the basic data for research into the impact of climate change over the *** dataset is available at https://***/10.57760/sciencedb.j00076.00121.

关键词： Greenland ice sheet elevation change volume change satellite altimetry

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A VGGNet-based correction for satellite altimetry-derived gravity anomalies to improve the accuracy of bathymetry to depths of 6500 m

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Acta Oceanologica Sinica 2024年第1期43卷 112-122页

作者： Xiaolun Chen Xiaowen Luo Ziyin Wu Xiaoming Qin Jihong Shang Huajun Xu Bin Li Mingwei Wang Hongyang Wan Key Laboratory of Submarine Geosciences Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Ocean College Zhejiang UniversityZhoushan 316021China Key Laboratory of Ocean Space Resources Management Technology Marine Academy of ZhejiangHangzhou 310012China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200240China School of Civil Engineering and Architectures Zhejiang University of Science and TechnologyHangzhou 310023China National Center for Archaeology Beijing 100013China

Understanding the topographic patterns of the seafloor is a very important part of understanding our *** the science involved in bathymetric surveying has advanced much over the decades,less than 20%of the seafloor has been precisely modeled to date,and there is an urgent need to improve the accuracy and reduce the uncertainty of underwater survey *** this study,we introduce a pretrained visual geometry group network(VGGNet)method based on deep *** apply this method,we input gravity anomaly data derived from ship measurements and satellite altimetry into the model and correct the latter,which has a larger spatial coverage,based on the former,which is considered the true value and is more *** obtaining the corrected high-precision gravity model,it is inverted to the corresponding bathymetric model by applying the gravity-depth *** choose four data pairs collected from different environments,i.e.,the Southern Ocean,Pacific Ocean,Atlantic Ocean and Caribbean Sea,to evaluate the topographic correction results of the *** experiments show that the coefficient of determination(R~2)reaches 0.834 among the results of the four experimental groups,signifying a high *** standard deviation and normalized root mean square error are also evaluated,and the accuracy of their performance improved by up to 24.2%compared with similar research done in recent *** evaluation of the R^(2) values at different water depths shows that our model can achieve performance results above 0.90 at certain water depths and can also significantly improve results from mid-water depths when compared to previous ***,the bathymetry corrected by our model is able to show an accuracy improvement level of more than 21%within 1%of the total water depths,which is sufficient to prove that the VGGNet-based method has the ability to perform a gravity-bathymetry correction and achieve outstanding results.

关键词： gravity anomaly bathymetry inversion VGGNet multibeam sonar satellite altimetry

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Mesoscale surface circulation and variability of Southern Indian Ocean derived by combining satellite altimetry and drifter observations

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Acta Oceanologica Sinica 2015年第9期34卷 12-22页

作者： BENNY N.Peter SHENBAKAVALLI Ranjan MAZLAN Hashim MOHD Nadzri Reba MOHD Razali Mahmud Department of Coastal and Offshore Engineering School of Ocean Engineering and Underwater TechnologyKerala University of Fisheries and Ocean Studies Department of Geomatic Engineering Faculty of Geoinformation and Real EstateUniversity of Technology Malaysia Institute of Geospatial Science & Technology Faculty of Geoinformation and Real EstateUniversity of Technology Malaysia

High resoultion Eulerian mean velocity field has been derived by combining the satellite tracked surface drifter data with satellite altimetry and ocean surface winds. The drifter data used in this study includes Argos and surface drifter data from Global Drifter Program. Maps of Sea Level Anomaly （MSLA） weekly files with a resolution of （1/3）° in both Latitude and Longitude for the period 1993-2012 have been used. The Ekman current is computed using ocean surface mean wind fields from scatterometers onboard ERS 1/2, Quikscat and ASCAT. The derived mean velocity field exhibits the broad flow of Antarctic Circumpolar Current with speeds up to 0.6 m/s. Anomalous field is quite significant in the western part between 20~ and 40~E and in the eastern part between 80~E and 100~E with velocity anomaly up to 0.3 m/s. The estimated mean flow pattern well agrees with the dynamic topography derived from in-situ observations. Also, the derived velocity field is consistent with the in-situ ADCP current measurements. Eddy kinetic energy illustrates an increasing trend during 1993-2008 and is in phase coherence with the Southern Annular Mode by three month lag. Periodic modulations are found in the eddy kinetic energy due the low frequency Antarctic Circumpolar Wave propagation.

关键词： Antarctic Ocean circulation satellite altimetry eddy kinetic energy Southern Indian Ocean antarctic circumpolar wave

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Patterns of upper layer circulation variability in the South China Sea from satellite altimetry using the self-organizing map

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Acta Oceanologica Sinica 2008年第Z1期27卷 129-144页

作者： WEISBERG Robert H College of Marine Science University of South Florida

Patterns of the South China Sea (SCS) circulation variability are extracted from merged satellite altimetry data from October 1992 through August 2004 by using the self-organizing map (SOM). The annual cycle, seasonal and inter-annual variations of the SCS surface circulation are identified through the evolution of the characteristic circulation *** annual cycle of the SCS general circulation patterns is described as a change between two opposite basin-scale SW-NE oriented gyres embedded with eddies: low sea surface height anomaly (SSHA) (cyclonic) in winter and high SSHA (anticyclonic) in summer half year. The transition starts from July—August (January—February) with a high (low) SSHA tongue east of Vietnam around 12°~14° N, which develops into a big anticyclonic (cyclonic) gyre while moving eastward to the deep basin. During the transitions, a dipole structure, cyclonic (anticyclonic) in the north and anticyclonic (cyclonic) in the south, may be formed southeast off Vietnam with a strong zonal jet around 10°~12° N. The seasonal variation is modulated by the interannual variations. Besides the strong 1997/1998 event in response to the peak Pacific El Nio in 1997, the overall SCS sea level is found to have a significant rise during 1999~2001, however, in summer 2004 the overall SCS sea level is lower and the basin-wide anticyclonic gyre becomes weaker than the other years.

关键词： circulation patterns self-organizing map satellite altimetry annual cycle inter-annual variation South China Sea

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Feasibility of maintaining satellite altimetry calibration site based on qianliyan islet at the Yellow Sea

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Geodesy and Geodynamics 2023年第3期14卷 223-230页

作者： Bin Guan Zhongmiao Sun Lei Yang Zhenhe Zhai Jian Ma State Key Laboratory of Geo-information Engineering Xi'an 710054China Xi'an Research Institute of Surveying and Mapping Xi'an 710054China First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China

The calibration of the sea surface height(SSH)measured by satellite altimeters is essential to understand altimeter *** factors affects the construction and maintenance of a permanent calibration *** order to calibrate Chinese satellite altimetry missions,the feasibility of maintaining a calibration site based on the Qianliyan islet in Yellow Sea of China is taken into *** related calibration facilities,such as the permanent tide gauge,GNSS reference station and meteorological station,were already operated by the Ministry of Natural Resources of *** data could be fully used for satellite altimeter calibration with small fiscal *** addition,the location and marine environments of Qianliyan were ***,we used the Jason-3 mission to check the possibility of calibration *** result indicates that the brightness temperatures of three channels measured by microwave radiometer(MWR)and the derived wet tropospheric correction varies smoothly,which means the land contamination to MWR could be *** high frequency waveforms at the Qianliyan site present no obvious difference from the normal waveforms received by satellite radar altimeter over the open *** conclusion,the Qianliyan islet will not influence satellite altimetry *** these analyses,a possible layout and mechanism of the Qianliyan calibration site are proposed.

关键词： satellite altimetry Altimeter calibration satellite radar altimeter Microwave radiometer Jason Tide gauge

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Absolute sea level variability of Arctic Ocean in 1993–2018 from satellite altimetry and tide gauge observations

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Acta Oceanologica Sinica 2021年第10期40卷 76-83页

作者： Yanguang Fu Yikai Feng Dongxu Zhou Xinghua Zhou First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China Key Laboratory of Marine Environmental Survey Technology and Application Ministry of Natural ResourcesGuangzhou 510310China College of Ocean Science and Engineering Shandong University of Science and TechnologyQingdao 266590China

Arctic absolute sea level variations were analyzed based on multi-mission satellite altimetry data and tide gauge observations for the period of 1993–*** range of linear absolute sea level trends were found-2.00 mm/a to 6.88 mm/a excluding the central Arctic,positive trend rates were predominantly located in shallow water and coastal areas,and negative rates were located in high-latitude areas and Baffin ***-derived results show that the average secular absolute sea level trend was(2.53±0.42)mm/a in the Arctic *** differences were presented between satellite-derived and tide gauge results,which are mainly due to low satellite data coverage,uncertainties in tidal height processing and vertical land movement(VLM).The VLM rates at 11 global navigation satellite system stations around the Arctic Ocean were analyzed,among which 6 stations were tide gauge colocated,the results indicate that the absolute sea level trends after VLM corrected were of the same magnitude as satellite altimetry *** calculating VLM is the primary uncertainty in interpreting tide gauge measurements such that differences between tide gauge and satellite altimetry data are attributable generally to VLM.

关键词： Arctic Ocean absolute sea level variability sea level anomaly satellite altimetry tide gauge

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Wetland hydrologic application of satellite altimetry-A case study in the Poyang Lake watershed

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Progress in Natural Science:Materials International 2009年第12期19卷 1781-1787页

作者： Xiaobin Cai~(a,b),Wei Ji~(b,*) a State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,Wuhan University,Wuhan 430079,China b Department of Geosciences,University of Missouri,Kansas City,Kansas City,MO 64110,USA State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan 430079 China Department of Geosciences University of Missouri Kansas City Kansas City MO 64110 USA

Hydrologic variation affects many functions of *** and accurately measuring hydrologic dynamics in a wetland watershed has become a fundamental need for estimating functional changes of *** satellite altimeters have become good data sources that can complement the measurements of gauge *** a case project applied in the Poyang Lake watershed,this study has developed a technical approach that integrates the altimeter measurements with the in situ water level *** derived water surface heights with Envisat RA-2 data are compared with the daily observations of in situ water *** average absolute observation difference between the"altimeter station"and its nearest gauge station is 0.307 m,which is comparable to the average differences among the gauge *** results suggest that the derived water surface heights from the altimeter data have a good accuracy,which can be used along with the in situ observations as supplements to fill the ungauged area in Poyang Lake wetlands.

关键词： satellite altimetry Wetland hydrology Poyang Lake

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Bathymetric Inversion of South China Sea from satellite altimetry Data

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Geo-Spatial Information Science 2003年第1期6卷 19-23页

作者： LUO Jia LI Jiancheng CHAO Dingbo School of Geodesy and Geomatics Wuhan University Wuhan China

This paper focuses on the study of ocean bathymetric inversion from satellite altimeter data by using FFT *** this study,the freeair gravity anomalies over the South China Sea are determined by the satellite altimeter data of GEOSAT,ERS1,ERS2 and T/*** the 2.5′×2.5′ bathymetry model in South China Sea is calculated from the gravity anomalies with the inversion model *** the analysis of the inversion and the comparison between the results,some conclusions can be drawn.

关键词： bathymetry satellite altimetry gravity anomaly FFT

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A High-Resolution Earth’s Gravity Field Model SGG-UGM-2 from GOCE,GRACE,satellite altimetry,and EGM2008

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Engineering 2020年第8期6卷 860-878页

作者： Wei Liang Jiancheng Li Xinyu Xu Shengjun Zhang Yongqi Zhao School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China Key Laboratory of Geospace Environment and Geodesy Ministry of EducationWuhan UniversityWuhan 430079China School of Resources and Civil Engineering Northeastern UniversityShenyang 110004China

This paper focuses on estimating a new high-resolution Earth’s gravity field model named SGG-UGM-2 from satellite gravimetry,satellite altimetry,and Earth Gravitational Model 2008(EGM2008)-derived gravity data based on the theory of the ellipsoidal harmonic analysis and coefficient transformation(EHA-CT).We first derive the related formulas of the EHA-CT method,which is used for computing the spherical harmonic coefficients from grid area-mean and point gravity anomalies on the *** derived formulas are successfully evaluated based on numerical ***,based on the derived least-squares formulas of the EHA-CT method,we develop the new model SGG-UGM-2 up to degree 2190 and order 2159 by combining the observations of the Gravity Field and Steady-State Ocean Circulation Explorer(GOCE),the normal equation of the Gravity Recovery and Climate Experiment(GRACE),marine gravity data derived from satellite altimetry data,and EGM2008-derived continental gravity *** coefficients of degrees 251–2159 are estimated by solving the block-diagonal form normal equations of surface gravity anomalies(including the marine gravity data).The coefficients of degrees 2–250 are determined by combining the normal equations of satellite observations and surface gravity *** variance component estimation technique is used to estimate the relative weights of different ***,global positioning system(GPS)/leveling data in the mainland of China and the United States are used to validate SGG-UGM-2 together with other models,such as European improved gravity model of the earth by new techniques(EIGEN)-6C4,GECO,EGM2008,and SGG-UGM-1(the predecessor of SGG-UGM-2).Compared to other models,the model SGG-UGM-2 shows a promising performance in the GPS/leveling *** GOCE-related models have similar performances both in the mainland of China and the United States,and better performances than that of EGM2008 in the mainland of *** to the contribut

关键词： Gravity field model GOCE GRACE satellite altimetry Block-diagonal least-squares

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Determination of Geoid over South China Sea and Philippine Sea from Multi-satellite altimetry Data

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Geo-Spatial Information Science 2007年第1期10卷 27-32页

作者： Isaac Dadzie Civil and Geomatic Engineering Kwame Nkrumah University of Science and TechnologyKumasiGhana

A new computational procedure for derivation of marine geoid on a 2.5′×2.5′grid in a non-tidal system over the South China Sea and the Philippine Sea from multi-satellite altimeter sea surface heights is discussed. Single-and dual-satellite crossovers were performed, and components of deflections of the vertical were determined at the crossover positions using Sand-well's computational theory, and gridded onto a 2.5′×2.5′resolution grid by employing the Shepard's interpolation procedure. 2.5′×2.5′grid of EGM96-derived components of deflections of the vertical and geoid heights were then used as reference global geopotential model quantities in a remove-restore procedure to implement the Molodensky-like formula via 1D-FFT technique to predict the geoid heights over the South China Sea and the Philippine Sea from the gridded altimeter-derived components of deflec-tions of the vertical. Statistical comparisons between the altimeter-and the EGM96- derived geoid heights showed that there was a root-mean-square agreement of ±0.35 m between them in a region of less tectonically active geological structures. However, over areas of tectonically active structures such as the Philippine trench, differences of about -19.9 m were obtained.

关键词： satellite altimetry sea surface height deflection of the vertical geoid height

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