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Tidal modeling based on satellite altimetry observations of TOPEX/Poseidon, Jason1, Jason2, and Jason3 with high prediction capability:A case study of the Baltic Sea

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Geodesy and Geodynamics 2024年第4期15卷 404-418页

作者： Alireza A.Ardalan Asiyeh Hashemifaraz School of Surveying and geospatial Engineering College of Engineering University of Tehran

This research aims to optimize the utilization of long-term sea level data from the TOPEX/Poseidon,Jason1, Jason2, and Jason3 altimetry missions for tidal modeling. We generate a time series of along-track observations and apply a developed method to produce tidal models with specific tidal constituents for each location. Our tidal modeling methodology follows an iterative process: partitioning sea surface height(SSH) observations into analysis/training and prediction/validation parts and ultimately identifying the set of tidal constituents that provide the best predictions at each time series location. The study focuses on developing 1256 time series along the altimetry tracks over the Baltic Sea, each with its own set of tidal constituents. Verification of the developed tidal models against the SSH observations within the prediction/validation part reveals mean absolute error(MAE) values ranging from 0.0334 m to0.1349 m, with an average MAE of 0.089 m. The same validation process is conducted on the FES2014 and EOT20 global tidal models, demonstrating that our tidal model, referred to as BT23(short for Baltic Tide2023), outperforms both models with an average MAE improvement of 0.0417 m and 0.0346 m,respectively. In addition to providing details on the development of the time series and the tidal modeling procedure, we offer the 1256 along-track time series and their associated tidal models as supplementary materials. We encourage the satellite altimetry community to utilize these resources for further research and applications.

关键词： Satellite altimetry Baltic Sea Ocean tide modeling Jason3 Jason2 Jason1 TOPEX/Poseidon EOT20 FES2014

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Full-domain collaborative deployment method of multiple interference sources and evaluation of its deployment effect

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Defence Technology（防务技术） 2024年第2期32卷 572-595页

作者： Yue Wang Fuping Sun Xian Wang Jinming Hao Kai Xiao School of geospatial Information The PLA Information Engineering UniversityZhengzhou 450001HenanChina

This paper realizes the full-domain collaborative deployment of multiple interference sources of the global satellite navigation system(GNSS)and evaluates the deployment effect to enhance the ability to disturb the attacker and the capability to defend the GNSS during navigation countermeasures.Key evaluation indicators for the jamming effect of GNSS suppressive and deceptive jamming sources are first created,their evaluation models are built,and their detection procedures are sorted out,as the basis for determining the deployment principles.The principles for collaboratively deploying multi-jamming sources are developed to obtain the deployment structures(including the required number,structures in demand,and corresponding positions)of three single interference sources required by collaboratively deploying.Accordingly,simulation and hardware-in-loop testing results are presented to determine a rational configuration of the collaborative deployment of multi-jamming sources in the set situation and further realize the full-domain deployment of an interference network from ground,air to space.Varied evaluation indices for the deployment effect are finally developed to evaluate the deployment effect of the proposed configuration and further verify its reliability and rationality.

关键词： Jamming effect Multiple interference sources Collaborative deployment Effect evaluation Defense capability

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Representation of three-dimensional mass distribution of the Earth's interior by biorthogonal series and its use for studying internal structure of the planet

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Geodesy and Geodynamics 2024年第3期15卷 264-275页

作者： Mykhailo Fys Mariana Yurkiv Andrii Brydun Andrii Sohor Department of Cartography and geospatial Modelling Lviv Polytechnic National UniversityLviv 79013Ukraine

This paper utilizes the mathematical concept of approximation within an ellipsoid from a single viewpoint to present the spatial mass distribution function of the Earth's interior and its internal potential.The primary focus lies in constructing the volume distribution of masses in the planet's interior, with the expansion coefficients being linear combinations of the Stokes constants. Several possible approaches are suggested for determining accurately these coefficients employing three-dimensional(biorthogonal)polynomials. By expressing the mass distribution function of the Earth's interior and its internal potential as a series, an algorithm is introduced for the calculation of gravitational energy. It allows us to estimate fluctuations in gravitational energy. The implementation of this algorithm offers the means of establishing the extent to which the Earth deviates from a state of hydrostatic equilibrium as a celestial body.Due to the aforementioned method, calculations have been conducted to validate its effectiveness and reliability. This example is given as an illustration of a given method for studying the internal structure of planets.

关键词： Mass distribution function Potential Stokes constants Biorthogonal polynomials

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Performance evaluation of HY-2 series satellites in marine gravity field recovery

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Geodesy and Geodynamics 2024年第4期15卷 397-403页

作者： Ruijie Hao Xiaoyun Wan Keyan Zhang School of Land Science and Technology China University of Geosciences (Beijing) School of geospatial Engineering and Science Sun Yat-Sen University

China has successfully launched four Haiyang-2(HY-2) series altimetry satellites. HY-2A has attracted significant attention in gravity field recovery, but the performance of other HY-2 series satellites,including HY-2B/C/D, is seldom discussed. This study evaluated the performance of all the HY-2 series satellites in recovering marine gravity field. First, the crossover discrepancies in sea surface height of the four satellites, HY-2A, HY-2B, HY-2C, and HY-2D, were analyzed to assess their altimetry stability. It was found that HY-2B had the best altimetry quality, followed by HY-2D. Subsequently, different combinations of altimetry data were used to calculate vertical deflections and gravity anomalies in the South China Sea(112°E-119°E, 12°N-20°N). The results showed that combining data from HY-2B, HY-2C, and HY-2D improved the inversion accuracy of gravity anomalies by 0.3 m Gal compared to using HY-2A data alone. HY-2C and HY-2D contributed to enhancing the accuracy of the east component of vertical deflections.

关键词： Satellite altimetry HY-2 Sea surface height Marine gravity field

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Characterization of Small-Scale Farmers and Assessment of Their Access to Crop Production Information in Selected Counties of Kenya

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Agricultural Sciences 2024年第5期15卷 565-589页

作者： Anastasia Mumbi Wahome John B. K. Kiema Galcano C. Mulaku Isaac Mukoko Department of geospatial & Space Technology University of Nairobi Nairobi Kenya Department of Public health Kenya Methodist University Nairobi Kenya

Small-scale farming accounts for 78% of total agricultural production in Kenya and contributes to 23.5% of the country’s GDP. Their crop production activities are mostly rainfed subsistence with any surplus being sold to bring in some income. Timely decisions on farm practices such as farm preparation and planting are critical determinants of the seasonal outcomes. In Kenya, most small-scale farmers have no reliable source of information that would help them make timely and accurate decisions. County governments have extension officers who are mandated with giving farmers advisory services to farmers but they are not able to reach most farmers due to facilitation constraints. The mode and format of sharing information is also critical since it’s important to ensure that it’s timely, well-understood and usable. This study sought to assess access to geospatial derived and other crop production information by farmers in four selected counties of Kenya. Specific objectives were to determine the profile of small-scale farmers in terms of age, education and farm size;to determine the type of information that is made available to them by County and Sub-County extension officers including the format and mode of provision;and to determine if the information provided was useful in terms of accuracy, timeliness and adequacy. The results indicated that over 80% of the farmers were over 35 years of age and over 56% were male. Majority had attained primary education (34%) or secondary education (29%) and most farmers in all the counties grew maize (71%). Notably, fellow farmers were a source of information (71%) with the frequency of sharing information being mostly seasonal (37%) and when information was available (43%). Over 66% of interviewed farmers indicating that they faced challenges while using provided information. The results from the study are insightful and helpful in determining effective ways of providing farmers with useful information to ensure maximum benefits.

关键词： Small Scale Farmers Farmers Crop Production Information Services geospatial Information Information Access

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Coseismic Coulomb stress changes induced by a 2020-2021 M_(W)>7.0 Alaska earthquake sequence in and around the Shumagin gap and its influence on the Alaska-Aleutian subduction interface

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Geodesy and Geodynamics 2024年第1期15卷 1-12页

作者： Lei Yang Jianjun Wang Caijun Xu School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China Collaborative Innovation Center of geospatial Technology Wuhan 430079China Key Laboratory of Geospace Environment and Geodesy Ministry of EducationWuhan UniversityWuhan 430079China

Three M_(W)>7.0 earthquakes in 2020-2021 occurred in the Shumagin seismic gap and its adjacent area of the Alaska-Aleutian subduction zone,including the Mw7.8 Simeonof thrust earthquake on July 22,2020,the M_(W)7.6 Sand Point strike-slip earthquake on October 19,2020,and the M_(W)8.2 Chignik thrust earthquake on July 29,2021.The spatial and temporal proximity of these three earthquakes prompts us to probe stress-triggering effects among them.Here we examine the coseismic Coulomb stress change imparted by the three earthquakes and their influence on the subduction interface.Our results show that:(1)The Simeonof earthquake has strong loading effects on the subsequent Sand Point and Chignik earthquakes,with the Coulomb stress changes of 3.95 bars and 2.89 bars,respectively.The Coulomb stress change caused by the Sand Point earthquake at the hypocenter of the Chignik earthquake is merely around 0.01 bars,suggesting the negligible triggering effect on the latter earthquake;(2)The triggering effects of the Simeonof,Sand Point,and Chignik earthquakes on aftershocks within three months are not well pronounced because of the triggering rates of 38%,14%,and 43%respectively.Other factors may have played an important role in promoting the occurrence of these aftershocks,such as the roughness of the subduction interface,the complicated velocity structure of the lithosphere,and the heterogeneous prestress therein;(3)The three earthquakes caused remarkable coseismic Coulomb stress changes at the subduction interface nearby these mainshocks,with an average Coulomb stress change of 3.2 bars in the shallow region directly inwards the trench.

关键词： The 2020-2021 Alaska earthquake sequence Coseismic Coulomb stress change Mainshock-aftershock triggering The Alaska-Aleutian subduction interface The Shumagin gap

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Analysis of the effect of the 2021 Semeru eruption on water vapor content and atmospheric particles using GNSS and remote sensing

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Geodesy and Geodynamics 2024年第1期15卷 33-41页

作者： Mokhamad Nur Cahyadi Arizal Bawasir Syachrul Arief Amien Widodo Meifal Rusli Deni Kusumawardani Yessi Rahmawati Ana Martina Putra Maulida Hilda Lestiana Department of Geomatics Engineering Institut Teknologi Sepuluh NopemberSurabaya 60111Indonesia Research Center of Marine and Earth Science-Technology Directorate of Research and Community ServiceInstitut Teknologi Sepuluh NopemberSurabaya 60111Indonesia geospatial Education and Training Division Geospatial Information Agency(BIG)Cibinong 16911Indonesia Department of Geophysics Engineering Institut Teknologi Sepuluh NopemberSurabaya 60111Indonesia Department of Mechanical Engineering Andalas UniversityPadang City 25175Indonesia Department of Economics Airlangga UniversitySurabaya 60286Indonesia Research Center for Geological Resources National Research and Innovation AgencyJakarta 10340Indonesia

Mount Semeru,an active volcano in East Java,Indonesia,erupted on December 4,2021,following extreme rainfall that caused an avalanche of hot pyroclastic flows and lava.The tropospheric conditions and dominant particle components in the atmosphere can be monitored using Global Navigation Satellite System(GNSS)technology and remote sensing satellites.GNSS signal propagation delay in Precise Point Positioning(PPP)processing can be used to determine Zenith Tropospheric Delay(ZTD)and Precipitable Water Vapor(PWV)variables so that atmospheric conditions can be generated.In addition,by using remote sensing satellite data,it is possible to obtain rainfall data with high temporal resolution as well as the dominant particle and gas content values during eruptions.During the eruption period,the high value of PWV was dominated by the high intensity of precipitation during the rainy season.High rainfall before the eruption caused activity inside the mountain to increase,which occurred in avalanche type eruption.Apart from that,the atmosphere around Semeru was also dominated by SO_(2)content,which spreaded for tens of kilometers.SO_(2)content began to be detected significantly by remote sensing sensors on December 7,2021.In this study,deformation and atmospheric monitoring were also carried out using low-cost GNSS at the Semeru Monitoring Station on September 9-15,2022.The results of the ZTD and ZWD values show the dominance of the wet component,which is directly proportional to rainfall activity in this period.

关键词： Semeru GNSS Water vapor Rainfall SO_(2)

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Variations of sediment organic phosphorus and organic carbon during the outbreak and decline of algal blooms in Lake Taihu,China

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Journal of Environmental Sciences 2024年第5期139卷 34-45页

作者： Jiehua Wang Xiuling Bai Wenchao Li Pingping Zhang Mengdi Zhang Haoran Wang Yingge Bai College of Geography and Environmental Science Henan UniversityKaifeng 475004China Key Laboratory of geospatial Technology for the Middle and Lower Yellow River Regions(Henan University) Ministry of EducationKaifeng 475004China National Demonstration Center for Environment and Planning Henan UniversityKaifeng 475004China Surrey International Institute Dongbei University of Finance and EconomicsDalian 116000China

In this study,sediment organic phosphorus(OP)and organic carbon(OC)in Lake Taihu,China,as well as their relationships,were analyzed during the outbreak and decline of algal blooms(ABs)over a five-month field study.The results showed synchronous temporal changes in the sediment OP and OC contents with the development of ABs.In addition,there was a significant positive correlation between the sediment OP and OC(p<0.01),suggesting simultaneous deposition and consumption during the ABs outbreak.The sediment OP and OC contents decreased significantly at the early and last stages of the ABs outbreak and increased at the peak of the ABs outbreak and during the ABs decline.These temporal variation patterns suggest that the sediment OC and OP contents did not consistently increase during the ABs outbreak,even though algae are an important source of organic matter in sediments.The depletion or enrichment of OC and OP in sediments may also depend on the scale of the ABs outbreak.The obtained results revealed significant differences in the sediment OC and OP contents between the months(p<0.05).In addition,OP in the sediments was dominated by orthophosphate diester(phospholipids and DNA-P)and orthophosphate monoester during the ABs outbreak and decline,respectively.The active OC contents and proportions in the sediments in the ABs outbreak were significantly lower than those observed in the ABs decline period,demonstrating the significant impacts of the ABs outbreak and decline on the sediment OC and OP in Lake Taihu.

关键词： Algal blooms Organic phosphorus Organic carbon Sediment ^(31)P NMR Lake Taihu

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An improved algorithm for retrieving thin sea ice thickness in the Arctic Ocean from SMOS and SMAP L-band radiometer data

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Acta Oceanologica Sinica 2024年第3期43卷 127-138页

作者： Lian He Senwen Huang Fengming Hui Xiao Cheng School of geospatial Engineering and Science Sun Yat-Sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Key Laboratory of Comprehensive Observation of Polar Environment(Sun Yat-Sen University) Ministry of EducationZhuhai 519082China

The aim of this study was to develop an improved thin sea ice thickness(SIT)retrieval algorithm in the Arctic Ocean from the Soil Moisture Ocean Salinity and Soil Moisture Active Passive L-band radiometer data.This SIT retrieval algorithm was trained using the simulated SIT from the cumulative freezing degree days model during the freeze-up period over five carefully selected regions in the Beaufort,Chukchi,East Siberian,Laptev and Kara seas and utilized the microwave polarization ratio(PR)at incidence angle of 40°.The improvements of the proposed retrieval algorithm include the correction for the sea ice concentration impact,reliable reference SIT data over different representative regions of the Arctic Ocean and the utilization of microwave polarization ratio that is independent of ice temperature.The relationship between the SIT and PR was found to be almost stable across the five selected regions.The SIT retrievals were then compared to other two existing algorithms(i.e.,UH_SIT from the University of Hamburg and UB_SIT from the University of Bremen)and validated against independent SIT data obtained from moored upward looking sonars(ULS)and airborne electromagnetic(EM)induction sensors.The results suggest that the proposed algorithm could achieve comparable accuracies to UH_SIT and UB_SIT with root mean square error(RMSE)being about 0.20 m when validating using ULS SIT data and outperformed the UH_SIT and UB_SIT with RMSE being about 0.21 m when validatng using EM SIT data.The proposed algorithm can be used for thin sea ice thickness(<1.0 m)estimation in the Arctic Ocean and requires less auxiliary data in the SIT retrieval procedure which makes its implementation more practical.

关键词： Arctic sea ice sea ice thickness remote sensing Soil Moisture Active Passive(SMAP) Soil Moisture Ocean Salinity and Soil(SMOS)

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Analysis of GPS Technology in Surveying and Mapping Engineering Technology

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Journal of World Architecture 2024年第2期8卷 84-89页

作者： Hanyu Zhao Institute of geospatial Information Information Engineering UniversityZhengzhou 450001Henan ProvinceChina

With the rapid advancement of digital and information technology,global positioning system(GPS)technology has seen increasing utilization in surveying and mapping engineering,extending its application across land,ocean,and various other domains.By analyzing the technical means of GPS in surveying and mapping engineering,understanding the characteristics and key technologies in different application environments,and exploring the application process and key technical means,accurate control can be effectively realized.Based on this,this paper mainly analyzes the specific application of GPS technology in surveying and mapping engineering technology for reference.

关键词： Surveying and mapping engineering technology GPS technology

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