Studia Geophysica et Geodaetica最新文献_第10页

Response of the electron density profiles to geomagnetic disturbances in January 2005 2005年1月电子密度剖面对地磁扰动的响应

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-07-02 DOI: 10.1007/s11200-019-0510-6

Rumiana Bojilova, Plamen Mukhtarov

{"title":"Response of the electron density profiles to geomagnetic disturbances in January 2005","authors":"Rumiana Bojilova, Plamen Mukhtarov","doi":"10.1007/s11200-019-0510-6","DOIUrl":"https://doi.org/10.1007/s11200-019-0510-6","url":null,"abstract":"The ionospheric response to geomagnetic storms is usually investigated by considering the variability of the critical frequency of the F2-layer (foF2) or the total electron content (TEC) because these two parameters are directly measured by the ionosonde stations and the Global Navigation Satellite Systems (GNSS). In the present paper, however, the reaction is explored by using the vertical profiles of the electron density, N(h), reconstructed by manually scaled ionosonde measurements at the station Sofia (42.4°N, 23.2°E). The mid-latitude ionosheric response to three geomagnetic storms that occurred in January 2005 is presented as this period has been selected because no major sudden stratospheric warming occurred during this month, and the winter 2005 is given in the literature as an example of a “normal” year. Hence the observed ionospheric response to the considered geomagnetic storms can be attributed mainly to the external forcing. Besides the traditional parameters foF2 and TEC, a particular attention is paid to the variability of the peak electron density height (hmF2). This study reveals for the first time that the main contribution to the response of the midlatitude ionosphere to moderate/intense winter geomagnetic storms is associated with significant enhancements of short-period quasi-diurnal oscillations with period of 6–7 hours observed in both foF2 and hmF2. An explanation of the main mechanisms responsible for the distortion of the diurnal ionospheric variability during these storms is offered. This result is especially important for the ground-based HF radio communications.","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"63 3","pages":"436 - 454"},"PeriodicalIF":0.9,"publicationDate":"2019-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-019-0510-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4086980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

An optimized method to transform the Cartesian to geodetic coordinates on a triaxial ellipsoid 一种将三轴椭球体上的笛卡尔坐标转换为大地坐标的优化方法

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-07-02 DOI: 10.1007/s11200-018-0589-1

Cheng Chen, Shaofeng Bian, Songlin Li

引用次数: 4

Robustness of Msplit(q) estimation: A theoretical approach Msplit(q)估计的稳健性:一种理论方法

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-07-02 DOI: 10.1007/s11200-018-0548-x

Robert Duchnowski, Zbigniew Wiśniewski

{"title":"Robustness of Msplit(q) estimation: A theoretical approach","authors":"Robert Duchnowski, Zbigniew Wiśniewski","doi":"10.1007/s11200-018-0548-x","DOIUrl":"https://doi.org/10.1007/s11200-018-0548-x","url":null,"abstract":"Msplit(q) estimation is a development of M-estimation which is based on the assumption that a functional model of observations can be split into q competitive ones. The main idea behind such an assumption is that the observation set might be a mixture of realizations of different random variables which differ from each other in location parameters that are estimated. The paper is focused on the robustness of Msplit(q) estimates against outlying observations. The paper presents derivatives of the general expressions of the respective influence functions and weight functions which are the main basis for theoretical analysis. To recognize the properties of Msplit(q) estimates in a better way, we propose considering robustness from two points of view, namely local and global ones. Such an approach is a new one, but it reflects the nature of the estimation method in question very well. Thus, we consider the local breakdown point (LBdP) and the global one (GBdP) that are both based on the maximum sensitivities of the estimates. LBdP describes the mutual relationship between the “neighboring” Msplit(q) estimates, whereas GBdP concerns the whole set of the estimates and describes the robustness of the method itself (in more traditional sense). The paper also presents GBdP with an extension, which shows how an outlier might influence Msplit(q) estimates. The general theory proposed in the paper is applied to investigate the squared Msplit(q) estimation, the variant which is used in some practical problems in geodesy, surveying, remote sensing or geostatistics, and which can also be applied in other geosciences.","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"63 3","pages":"390 - 417"},"PeriodicalIF":0.9,"publicationDate":"2019-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-018-0548-x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4084459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

IRG2018: A regional geoid model in Iran using Least Squares Collocation IRG2018:基于最小二乘配置的伊朗区域大地水准面模型

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-05-27 DOI: 10.1007/s11200-018-0116-4

Sabah Ramouz, Yosra Afrasteh, Mirko Reguzzoni, Abdolreza Safari, Abdoreza Saadat

{"title":"IRG2018: A regional geoid model in Iran using Least Squares Collocation","authors":"Sabah Ramouz, Yosra Afrasteh, Mirko Reguzzoni, Abdolreza Safari, Abdoreza Saadat","doi":"10.1007/s11200-018-0116-4","DOIUrl":"https://doi.org/10.1007/s11200-018-0116-4","url":null,"abstract":"The aim of this study is to determine an accurate geoid model for Iran based on the Least Squares Collocation method in the framework of the Remove — Compute — Restore technique. In areas suffering from a lack of homogeneous and accurate gravity anomaly data, as is the case of Iran, the choice of the most compatible global gravity model has a significant impact on the estimated form of the geoid. Different combined and satellite-only global gravity models were therefore analyzed for Iran, and EIGEN6C4 was selected as the best one. The Shuttle Radar Topography Mission height model was used for the residual terrain correction. The covariance modeling, a crucial step in the Least Squares Collocation method, was based on two strategies. In the first, the study area was divided into four sub-areas, and then an individual empirical covariance was computed and a covariance model fitted to each of them. In the second, an empirical covariance was computed using all terrestrial gravity data, and a unique covariance model was fitted to it. Despite some border effects, the former strategy showed slightly better performance according to the resulting statistics, and therefore it was preferred for the estimation of the geoid model called IRG2018. To remove the offset of IRG2018 with respect to GNSS/Leveling-derived geoid heights, two alternative approaches were tested: subtracting a fitting polynomial surface or directly using the GNSS/Leveling data as an input to the IRG2018 computation process. Evaluation of the results, based on an independent control set of approximately half of available GNSS/Leveling points, showed an advantage of the latter approach, with an estimated accuracy of about 20 cm in terms of RMS.","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"63 2","pages":"191 - 214"},"PeriodicalIF":0.9,"publicationDate":"2019-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-018-0116-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5051107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

Transient compression fault slip detected within andesitic rocks of the Casma Group, Lima, Peru 秘鲁利马卡斯玛群安山岩中探测到的瞬时压缩断层滑动

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-05-27 DOI: 10.1007/s11200-018-2912-2

Jan Klimeš, Edmundo Norabuena, Josef Stemberk, Miloš René

{"title":"Transient compression fault slip detected within andesitic rocks of the Casma Group, Lima, Peru","authors":"Jan Klimeš, Edmundo Norabuena, Josef Stemberk, Miloš René","doi":"10.1007/s11200-018-2912-2","DOIUrl":"https://doi.org/10.1007/s11200-018-2912-2","url":null,"abstract":"A fault slip within the ?a?a tunnel Lima, Peru has been monitored since 2012. The data are recorded using an optical-mechanical 3D extensometer, capable of providing very precise long-term three-dimensional measurements of relative displacement across discontinuities. The ?a?a tunnel has an extremely stable environment and cannot possibly be affected by gravitationally-induced mass movements. The host rock of the tunnel is an aphanitic hornblende-bearing basaltic trachyandesite. Several fault and fracture zones detected in the tunnel represent the major discontinuities of the broader surrounding of the monitored site. The recorded fault slip on the NNW-SSE and E-W striking fracture and fault, with inclinations of 76° to WSW and 78° to N respectively, appoint to compressional event (discontinuity contraction) with a maximum horizontal compression stress axis oriented approximately WSW to ENE corresponding to the direction of the Nazca and South America plates convergence. This event resulted in an aseismic slow fault slip between July 2012 and May 2013. The anticipated compression orientation matches the previously published in-situ stress measurements and fault plane solutions, as well as GPS measurements of the movements of the corresponding part of the Peruvian coast. Nevertheless, the presented monitoring results reflect only short-term fault slip dynamics and need to be considered with caution, even though they correspond to the overall tectonic activity driven by continental subduction.","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"63 2","pages":"257 - 272"},"PeriodicalIF":0.9,"publicationDate":"2019-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-018-2912-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5493317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Comparison of ray-matrix and finite-difference methods in a simple 1-D velocity model 简单一维速度模型中射线矩阵法与有限差分法的比较

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-05-27 DOI: 10.1007/s11200-018-1152-9

Ludĕk Klimeš

引用次数: 0

Regional improvement of global geopotential models using GPS/Leveling data 基于GPS/水准数据的全球位势模型的区域改进

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-05-27 DOI: 10.1007/s11200-017-1084-9

Mahdi Mosayebzadeh, Alireza A. Ardalan, Roohollah Karimi

{"title":"Regional improvement of global geopotential models using GPS/Leveling data","authors":"Mahdi Mosayebzadeh, Alireza A. Ardalan, Roohollah Karimi","doi":"10.1007/s11200-017-1084-9","DOIUrl":"https://doi.org/10.1007/s11200-017-1084-9","url":null,"abstract":"Global geopotential models are widely used in the remove-compute-restore technique for local gravity field modeling. In this paper, a method for regional improvement of global geopotential models using GPS/Leveling data is presented. The part of the spherical harmonic expansion degrees that can be subject to the regional improvement is determined depending on the spatial resolution of the GPS/Leveling data and the size of the study region. In this method, a global geopotential model is required as the original model. Using the GPS/Leveling data corrected for the systematic errors, the geoid surface is obtained at the GPS/Leveling points. By expanding the gravity potential of the geoid surface into the spherical harmonics, a mathematical model is made to estimate the spherical harmonic coefficients of the regionally improved geopotential model. To stabilize the mathematical model, pseudo data of the gravitational potential type produced by the original model on the entire Earth’s surface are added to the GPS/Leveling data. The relative weight of the two types of the data, i.e., the GPS/Leveling data and the pseudo data, is selected based on fitting the original model to the GPS/Leveling data. As numerical tests, the regionally improved geopotential model of the USA from degree 8 to 779 and the regionally improved geopotential model of Iran from degree 12 to 339 are developed. To develop both regionally improved geopotential models, the EGM2008 model up to degree 2160 is selected as the original model. The assessments at the GPS/Leveling checkpoints show that the regionally improved geopotential model of the USA has a 23% improvement and the regionally improved geopotential model of Iran has an 8% improvement with respect to the original model. The numerical tests confirm the efficiency of the proposed method for the regional improvement of global geopotential models using the GPS/Leveling data.","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"63 2","pages":"169 - 190"},"PeriodicalIF":0.9,"publicationDate":"2019-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-017-1084-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5053822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Deep lithospheric structure beneath the Polish part of the East European Craton as a result of magnetotelluric surveys 根据大地电磁测量结果，东欧克拉通波兰部分的深层岩石圈结构

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-05-27 DOI: 10.1007/s11200-017-1264-7

Szymon Oryński, Wojciech Klityński, Anne Neska, Katarzyna Ślęzak

引用次数: 9

Earth mantle conductivity beneath the Ukrainian territory 乌克兰领土下的地球地幔电导率

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-05-27 DOI: 10.1007/s11200-018-0347-4

Borys Ladanivskyy, Igor Logvinov, Victor Tarasov

{"title":"Earth mantle conductivity beneath the Ukrainian territory","authors":"Borys Ladanivskyy, Igor Logvinov, Victor Tarasov","doi":"10.1007/s11200-018-0347-4","DOIUrl":"https://doi.org/10.1007/s11200-018-0347-4","url":null,"abstract":"Magnetovariation methods, which are applicable to study the mantle conductivity, require long lasting registration of natural magnetic field variations. Such data usually can be recorded in stationary conditions on geomagnetic observatories. The magnetotelluric and magnetovariation measurements have been carried out at seven semi-permanent sites on Ukrainian territory for approximately 10–15 years by the Ukrainian State Geological Research Institute as well as the S.I. Subbotin Institute of Geophysics of the National Academy of Sciences of Ukraine for monitoring the effects and phenomena related to electromagnetic field. Since the quality of records was acceptable, we used these data to study the Earth’s mantle conductivity peculiarities to obtain the information on sites remote from geomagnetic observatories. The Z-H method was applied to collected data to estimate the magnetovariaton transfer functions, which were concatenated with magnetotelluric ones and further inverted by the 1D OCCAM algorithm to obtain the geoelectrical cross sections for the measuring sites. To extend the region under study and to obtain more reliable results, similar data from three Ukrainian geomagnetic observatories in Kyiv, Lviv and Odessa were included in this study. Obtained conductivity models were related to the known geological structure in the upper and middle mantle beneath the Ukrainian territory.","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"63 2","pages":"290 - 303"},"PeriodicalIF":0.9,"publicationDate":"2019-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-018-0347-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5051109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Employing the bilateral filter to improve the derivative-based transforms for gravity and magnetic data sets 利用双边滤波器改进重磁数据集的导数变换

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2019-05-27 DOI: 10.1007/s11200-018-0162-y

Jun Wang, Xiaohong Meng

{"title":"Employing the bilateral filter to improve the derivative-based transforms for gravity and magnetic data sets","authors":"Jun Wang, Xiaohong Meng","doi":"10.1007/s11200-018-0162-y","DOIUrl":"https://doi.org/10.1007/s11200-018-0162-y","url":null,"abstract":"In the literature, there are numerous derivative-based transforms for gravity and magnetic data sets, with which relevant features can be highlighted. However, almost all of them face the problem of instability in derivative calculation. Therefore, before applying derivative-based transforms, noise reduction is often applied to improve the quality of the data. Nevertheless, the application of conventional filters typically blurs horizontal gradients in the data, which can adversely affect subsequent transforms, for example, the sharp boundaries of the causative bodies may be obscured. To handle the above issue, this study is the first to employ the bilateral filter, used in digital image processing, for improving the derivative-based transforms for gravity and magnetic data sets. The filter replaces each data point by a weighted average of its neighbors. The established weights take into account both the geometric and amplitude closeness between the data points used. Synthetic tests indicate that the proposed method can effectively filter potential field data without distorting the structural features greatly. Thus, the performance of subsequent derivative-based transforms can be improved. The new method was applied to the magnetic data collected over the Dapai polymetallic deposit in Fujian Province, South China. This real example shows that the results obtained from the proposed method contain more pronounced features of existing faults and thus contributes to further geological interpretation.","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"63 2","pages":"215 - 228"},"PeriodicalIF":0.9,"publicationDate":"2019-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-018-0162-y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5056347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4