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A Comparative Study of Ionospheric Correction on SAR Interferometry—A Case Study of L’Aquila Earthquake

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Journal of Geodesy and Geoinformation Science 2022年第1期5卷 5-13页

作者： Yufang HE Wu ZHU Yang LEI Qin ZHANG Zhenhong LI Institute of Space Science and Applied Technology Harbin Institute of Technology(Shenzhen)Shenzhen 518055China gfz german research centre for geosciences Department of GeodesySection of Remote SensingPotsdam 14473Germany School of Geology Engineering and Geomatics Chang’an UniversityXi’an 710054China Key Laboratory of Western China’s Mineral Resource and Geological Engineering Ministry of EducationXi’an 710054China

Synthetic Aperture Radar Interferometry(InSAR)has shown its potential on seismic deformation monitoring since it can achieve the accuracy of centimeter level or even the millimeter level.However,the irregular varieties of ionosphere can induce the additional phase delay on SAR interferometry,restricting its further application in high-precision deformation monitoring.Although several methods have been proposed to correct the ionospheric phase delay on SAR interferometry,the performances of them haven't been evaluated and compared.In this study,three commonly used methods,including polynomial fitting,azimuth offset and split-spectrum are applied to L'Aquila Earthquake to correct the ionospheric phase delay on two Phased Array type L-band Synthetic Aperture Radar(PALSAR)onboard the Advanced Land Observing Satellite-1(ALOS-1)images.The result indicates that these three methods can effectively correct the ionospheric phase delay error for SAR interferometry,where the standard deviations of the ionosphere-corrected results have decreased by almost a factor of 1.8 times for polynomial fitting method,4.2 times for azimuth offset method and 2.5 times for split-spectrum method,compared to those of the original phase.Furthermore,the result of the sliding distribution inversion of the seismic fault shows the best performance for split-spectrum method.

关键词： SAR interferometry ionospheric effects split-spectrum method azimuth offset method performance evaluation

Impacts of Soil Additives on Crop Yield and C-Sequestration in Post Mine Substrates of Lusatia,germany

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Pedosphere 2012年第3期22卷 343-350页

作者： A.RODIONOV S.NII-ANNANG O.BENS M.TRIMBORN S.SCHILLEM B.U.SCHNEIDER T.RAAB R.F.HTTL Institute of Crop Science and Resource Conservation University of BonnBonn 53115 (Germany) Faculty of Environmental Science and Process Engineering Brandenburg University of TechnologyCottbus 03046 (Ger-many) german research centre for geosciences gfz Potsdam 14473 (Germany)

Opencast lignite mining in the Lusatia region of germany has resulted in large scale landscape disturbances,which require suitable recultivation techniques in order to promote plant growth and establishment in the remaining nutrient-poor substrates with low water-holding capacity.Thus,the effects of two commercial soil additives (CSA),a hydrophilic polymer mixed with volcanic rock flour and bentonite (a-CSA),and digester solids from biogas plants enriched with humic acids and bentonite (b-CSA),on soil organic carbon (SOC) storage,plant yields and root biomass were assessed after cultivating perennial crops (Dactylis glomerata L.) in monoculture and Helianthus annuus L.-Brassica napus L.in crop rotation systems.The CSA were incorporated into the top 20 cm soil depth using a rotary spader.The results indicated that a-CSA led to a significant increase in plant yield during the first year,and improved root biomass in the following year.As a result,SOC stocks increased,especially in the 0-10 cm soil layer.No significant sequestration of additional SOC was observed on b-CSA-amended plots at the end of both years.Bulk density values decreased in all treatments under the monoculture system.It can be concluded that application of a-CSA enhanced soil water availability for plant uptake and consequently promoted plant growth and organic carbon sequestration.The relative enrichment of organic matter without effects on water-holding capacities of b-CSA treatments suggested that it was not suitable for rapid land reclamation.

关键词：土壤添加剂作物产量封存基板德国土地复垦技术土壤有机碳邮政

Challenges and strategies for the visual exploration of complex environmental data

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International Journal of Digital Earth 2017年第10期10卷 1070-1076页

作者： Carolin Helbig Doris Dransch Michael Böttinger Colin Devey Antonie Haas Mario Hlawitschka Claudia Kuenzer Karsten Rink Christian Schäfer-Neth Gerik Scheuermann Tom Kwasnitschka Andrea Unger Helmholtz centre for Environmental research(UFZ) LeipzigGermany german research centre for geosciences(gfz) PotsdamGermany german Climate Computing centre(DKRZ) HamburgGermany Helmholtz centre for Ocean research Kiel(GEOMAR) KielGermany Helmholtz centre for Polar and Marine research(AWI) BremerhavenGermany Faculty of Computer Science Mathematics and Natural SciencesLeipzig University of Applied Sciences(HTWK)LeipzigGermany german Aerospace centre(DLR) OberpfaffenhofenGermany Institute of Computer Science Leipzig UniversityLeipzigGermany

In this opinion paper,we,a group of scientists from environmental-,geo-,ocean-and information science,argue visual data exploration should become a common analytics approach in Earth system science due to its potential for analysis and interpretation of large and complex spatio-temporal data.We discuss the challenges that appear such as synthesis of heterogeneous data from various sources,reducing the amount of information and facilitating multidisciplinary,collaborative research.We argue that to fully exploit the potential of visual data exploration,several bottlenecks and challenges have to be addressed:providing an efficient data management and an integrated modular workflow,developing and applying suitable visual exploration concepts and methods with the help of effective and tailored tools as well as generating and raising the awareness of visual data exploration and education.We are convinced visual data exploration is worth the effort since it significantly facilitates insight into environmental data and derivation of knowledge from it.

关键词： Digital Earth geoinformatics geospatial data integration visualization

Performance investigation of LAMBDA and bootstrapping methods for PPP narrow-lane ambiguity resolution

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Geo-Spatial Information Science 2021年第4期24卷 604-614页

作者： Omer Faruk Atiz Sermet Ogutcu Salih Alcay Pan Li Ilkay Bugdayci Department of Geomatics Engineering Necmettin Erbakan UniversityKonyaTurkey Department of Geodesy and Remote Sensing German Research Centre for GeosciencesPotsdamGermany

Precise point positioning with ambiguity resolution(PPP-AR)is a powerful tool for geodetic and time-constrained applications that require high precision.The performance of PPP-AR highly depends on the reliability of the correct integer carrier-phase ambiguity estimation.In this study,the performance of narrow-lane ambiguity resolution of PPP using the Least-squares AMBiguity Decorrelation(LAMBDA)and bootstrapping methods is extensively investigated using real data from 55 IGS stations over one-month in 2020.Static PPP with 24-,12-,8-,4-,2-,1-and½-h sessions using two different cutoff angles(7°and 30°)was conducted with three PPP modes:i.***.ambiguity-float and two kinds of ambiguity-fixed PPP using the LAMBDA and bootstrapping methods for narrow-lane AR,respectively.The results show that the LAMBDA method can produce more reliable results for 2 hour and shorter observation sessions com-pared with the bootstrapping method using a 7°cutoff angle.For a 30°cutoff angle,the LAMBDA method outperforms the bootstrapping method for observation sessions of 4 h and less.For long observation times,the bootstrapping method produced much more accurate coordinates compared with the LAMBDA method without considering the wrong fixes cases.The results also show that occurrences of fixing the wrong integer ambiguities using the bootstrapping method are higher than that of the LAMBDA method.

关键词： Ambiguity resolution narrow-lane Precise point positioning(PPP) LAMBDA bootstrapping

Root Exudation of Organic Acids of Herbaceous Pioneer Plants and Their Growth in Sterile and Non-Sterile Nutrient-Poor,Sandy Soils from Post-Mining Sites

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Pedosphere 2019年第1期29卷 34-44页

作者： Katja BOLDT-BURISCH Bernd Uwe SCHNEIDER M.Anne NAETH Reinhard F.HTTL Chair of Soil Protection and Recultivation Brandenburg University of Technology Helmholtz centre Potsdam-german research centre for geosciences Department of Renewable Resources University of Alberta

Nutrient-poor, sandy soils form the prevailing substrate at post-mining sites of the Lusatian region(Brandenburg, germany) and present a challenge for vegetation development. We studied the organic acid quantity and composition of three commonly occurring pioneer plant species, the legumes Lotus corniculatus L. and Trifolium arvense L. and the grass Calamagrostis epigeios(L.) Roth, to determine if plant growth and exudation differed with(non-sterilized soil) and without(sterilized soil) an indigenous soil microbial community. We investigated whether organic acids were found in the rhizosphere and surrounding soil and whether this influenced nutrient mobilization. This study consists of linked field investigations and a greenhouse experiment. Plants were grown in the greenhouse in either sterilized or non-sterilized sandy soil from a reclamation site in the Lusatian mining landscape(Welzow Su¨d, East germany). After seven months, the plant biomass, root morphology, organic acids, and water-soluble nutrients and root colonization with arbuscular mycorrhizal fungi(AMF) and dark septate endophytes(DSE) were analyzed. Roots of all three plants in the field and greenhouse experiments were highly colonized with AMF. Calamagrostis epigeios and T. arvense had a significantly higher colonization frequency with DSE than L. corniculatus. The quantity and composition of organic acids strongly differed among plant species, with the highest number of organic acids found for L. corniculatus and lowest for C. epigeios. The quantity of organic acids was greatly reduced in all plants under sterilized soil conditions. However, the composition of organic acids and plant growth in sterilized soil were reduced for both legumes, but not for C. epigeios, which had a higher biomass under sterilized conditions. Changes in nutrient concentrations in the field rhizosphere soil relative to those in the control were measurable after seven months. While the spectrum of organic acids and the growth of legumes seemed to be dependent on a highly d

关键词： Calamagrostis epigeios indigenous soil microbial community Lotus corniculatus microbial colonization mining landscape nutrient mobilization root symbiotic partner Trifolium arvense

Low-frequency Rayleigh waves excited by the Jan. 15, 2022 eruption of Hunga Tonga-Hunga Ha'apai volcano

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Low-frequency Rayleigh waves excited by the Jan. 15, 2022 er...

Precise Orbit Determination for the FY-3C Satellite Using Onboard BDS and GPS Observations from 2013, 2015, and 2017

2022年中国地球科学联合学术年会

作者： Shenjian ZHANG Rongjiang WANG Xiaofei CHEN Southern University of Science and Technology gfz german research centre for geosciences Potsdam

After the powerful eruption of Hunga Tonga-Hunga Ha’apai volcano on Jan. 15, 2022, low-frequency signals are detected on long period and very long period seismometers worldwide. The amplitude spectrum of this kind of signals consists of three clear peaks locating at 3.72, 4.61 and 6.07 m Hz. The spectrogram analysis shows that this low-frequency energy lasts for several hour and is independent of air wave arrival, while normal-mode analysis relates this signal to the resonances between the atmosphere and the solid earth.

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Engineering 2020年第8期6卷 904-912页

作者： Xingxing Li Keke Zhang Xiangguang Meng Wei Zhang Qian Zhang Xiaohong Zhang Xin Li School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China german research centre for geosciences(gfz) Potsdam 14473Germany National Space Science Center Chinese Academy of SciencesBeijing 100190China Beijing Key Laboratory of Space Environment Exploration Beijing 100190China

Using the FengYun-3C(FY-3C)onboard BeiDou Navigation Satellite System(BDS)and Global Positioning System(GPS)data from 2013 to 2017,this study investigates the performance and contribution of BDS to precise orbit determination(POD)for a low-Earth orbit(LEO).The overlap comparison result indicates that code bias correction of BDS can improve the POD accuracy by 12.4%.The multi-year averaged one-dimensional(1D)root mean square(RMS)of the overlapping orbit differences(OODs)for the GPS-only solution is 2.0,1.7,and 1.5 cm,respectively,during the 2013,2015,and 2017 periods.The 1D RMS for the BDS-only solution is 150.9,115.0,and 47.4 cm,respectively,during the 2013,2015,and 2017 periods,which is much worse than the GPS-only solution due to the regional system of BDS and the few BDS channels of the FY-3C receiver.For the BDS and GPS combined solution(also known as the GC combined solution),the averaged 1D RMS is 2.5,2.3,and 1.6 cm,respectively,in 2013,2015,and 2017,while the GC combined POD presents a significant accuracy improvement after the exclusion of geostationary Earth orbit(GEO)satellites.The main reason for the improvement seen after this exclusion is the unfavorable satellite tracking geometry and poor orbit accuracy of GEO satellites.The accuracy of BDS-only and GC combined solutions have gradually improved from 2013 to 2017,thanks to improvements in the accuracy of International GNSS Service(IGS)orbit and clock products in recent years,especially the availability of a high-frequency satellite clock product(30 s sampling interval)since 2015.Moreover,the GC POD(without GEO)was able to achieve slightly better accuracy than the GPS-only POD in 2017,indicating that the fusion of BDS and GPS observations can improve the accuracy of LEO POD.GC combined POD can significantly improve the reliability of LEO POD,simply due to system redundancy.An increased contribution of BDS to LEO POD can be expected with the launch of more BDS satellites and with further improvements in the accuracy of BDS satellite products in the ne

关键词： FengYun-3C LEO precise orbit determination(POD) Onboard BDS and GPS BDS code bias BDS/GPS combined POD

The contribution of maps to the challenges of risk communication to the public

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International Journal of Digital Earth 2010年第3期3卷 292-311页

作者： Doris Dransch Henry Rotzoll Kathrin Poser Helmholtz centre Potsdam German Research Centre for GeosciencesPotsdamGermany Institute for Geography Humboldt-University BerlinBerlinGermany Center for Disaster Management and Risk Reduction Technology(CEDIM) PotsdamGermany

Risk communication is a significant challenge in risk management.It serves different purposes;an important one is to improve the public risk awareness and mitigation.Because of the strong spatio-temporal component of natural hazards,maps can play a decisive role in communicating risk information.The application and design of maps for risk communication especially to the public has not been investigated comprehensively.Specific constraints and challenges of risk communication have not been considered systematically in the map design process so far.This study aims at developing a frame for the application and design of interactive risk and hazard maps for the public which is based on the specific constraints and challenges of risk communication.In a literature review it introduces concepts and methods from social sciences and psychology,which have been assessed as important for communicating risk information.The concepts and methods are adapted to map-mediated risk communication according to the approaches of Activity Theory.Communication objectives and tasks which are essential to improve risk mitigation are identified and geovisualization methods for information presentation are related according to the degree which they are able to serve them.Based on this,some principles for map-based risk communication are established.

关键词： risk management risk communication risk mitigation risk maps task-oriented geovisualization Digital Earth visualization geoinformatics GIS

The Lower Mantle Minerals in Ophiolite-hosted Diamond

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Acta Geologica Sinica(English Edition) 2015年第A2期89卷 108-109页

作者： YANG Jingsui WIRTH Richard XIONG Fahui TIANYazhou HUANG Zhu ROBINSON Paul T DILEK Yildirim CARMA Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China Helmholtz centre Potsdam GFZ German Research Centre for Geosciences Germany Department of Geology Miami University Oxford Ohio USA

Ophiolites are fragments of ancient ocean lithosphere emplaced on continental margins, in island arcs or in accretionary prisms, and have long been studied to better understand the evolution of ocean basins and collision of tectonic plates, the processes of mountain building and the occurrence of valuable ore bodies, such as podiform chromitites （Dilek and Fumes, 2011）.

关键词： CALCIUM silicates PEROVSKITE DIAMONDS CHROMITE OPHIOLITES