Acta Geodaetica et Geophysica最新文献

{"title":"Latitudinal propagation and solar wind drivers of Pc5 pulsations during the June 2015 geomagnetic storm","authors":"J. A. Lazzús,&nbsp;I. Salfate,&nbsp;M. N. Castillo,&nbsp;J. Lorca-Castillo,&nbsp;C. Olivares-Salazar,&nbsp;A. Rivera-Zepeda","doi":"10.1007/s40328-025-00469-y","DOIUrl":"10.1007/s40328-025-00469-y","url":null,"abstract":"<div><p>This study investigates the occurrence of Pc5 pulsations in the 2 to 7 mHz range at mid and low latitudes during the severe geomagnetic storm of June 21–24, 2015. This analysis employs two ground-based magnetic stations from the SAMBA network at magnetic latitudes − 16.55 and − 49.74, located in Chile and Antarctica, respectively, to explore the latitudinal distribution and drivers of Pc5 pulsations throughout the storm. Our results reveal that the intense pulsations recorded at low latitudes are synchronized with those observed at mid-latitudes and coincide with the arrival of the four interplanetary shocks associated with this event. Notably, the amplitudes of Pc5 pulsations exhibit significant latitudinal dependence, decreasing as they propagate from mid to low latitudes. Cross-correlation analyses highlight strong relationships between Pc5 amplitudes and solar wind parameters, indicating that solar wind dynamics played a critical role in the generation and propagation of these pulsations during this storm.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 2","pages":"205 - 217"},"PeriodicalIF":1.8,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145144390","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}

{"title":"Effect of the UNB topographical density model on geoid determination of Sarajevo, Bosnia & Herzegovina","authors":"Dževad Krdžalić,&nbsp;Džanina Omićević,&nbsp;Esad Vrce,&nbsp;Ervin Redžepagić,&nbsp;Jasmin Ćatić,&nbsp;Ramazan Alpay Abbak","doi":"10.1007/s40328-025-00467-0","DOIUrl":"10.1007/s40328-025-00467-0","url":null,"abstract":"<div><p>This study assesses the effect of the UNB Topographical Density Model on the accuracy of geoid determination in Sarajevo, Bosnia &amp; Herzegovina. Using the KTH method, 1020 gravimetric geoid models were developed, incorporating both constant and variable density values, simple and complete Bouguer anomalies. The study found that the model computed by the UNB Topographical Density Model and complete Bouguer anomalies achieved the highest precision, with an RMSE of 1.33 cm. The final geoid model was adjusted to the old vertical datum (Trieste height), resulting in an RMSE of 3.44 cm when tested with static GNSS points. These findings underscore the importance of incorporating variable density models for improving geoid accuracy and suggest further refinement using local geological data could enhance precision.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 2","pages":"219 - 242"},"PeriodicalIF":1.8,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145143051","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}

{"title":"Rapid 3D cross-correlation imaging of potential field data for mapping iron deposits: a case study from the Shavaz region","authors":"Saeed Ghanbarifar,&nbsp;Seyed Hossein Hosseini,&nbsp;Fardin Jokar,&nbsp;Maysam Abedi,&nbsp;Ali Moradzadeh","doi":"10.1007/s40328-025-00462-5","DOIUrl":"10.1007/s40328-025-00462-5","url":null,"abstract":"<div><p>This study explores the application of a rapid 3D cross-correlation imaging technique for analyzing potential field gravity and magnetic data. The approach involves calculating cross-correlation values between observed potential field anomalies and theoretical data, followed by the assessment of correlation coefficients. The method's efficacy was demonstrated through preliminary tests on various synthetic models with differing characteristics, highlighting its ability to detect and accurately locate subsurface sources, even in complex scenarios with inclined and multiple sources. The 3D imaging outcomes provided comprehensive insights into the location and center of anomaly sources. The methodology was then applied to ground magnetic and gravity datasets to evaluate the spatial distribution of underground iron deposits in the Shavaz region. The results closely matched drilling data and prior studies in the area, reinforcing the technique's effectiveness in interpreting real geophysical data. This research emphasizes the advantages of the cross-correlation imaging method in enhancing the understanding of subsurface structures, revealing hidden anomalies, and estimating the depth and arrangement of buried features.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 2","pages":"179 - 204"},"PeriodicalIF":1.8,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145144151","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}

{"title":"Gradient resistivity trends modeling of the Quaternary aquifer and its overlaying and underlying layers in the semi-arid Khanasser valley region, northern Syria","authors":"Jamal Asfahani","doi":"10.1007/s40328-025-00464-3","DOIUrl":"10.1007/s40328-025-00464-3","url":null,"abstract":"<div><p>Vertical electrical sounding (<i>VES</i>) technique is applied in this paper to assess and follow the trends of layered gradient resistivity (<i>GR</i>) variations and aquifer vulnerability to contamination in the Khanasser Valley region, Northern Syria. GR parameter, termed also as longitudinal resistance (<i>LR</i>), having the Ohm unit (Ω) is therefore developed in this paper. <i>GR</i> is by definition the inverse of longitudinal conductance (<i>LC</i>) (one of the second order Dar-Zarrouk geo-electric indices). A model composed of three hydrological layers is used to test and characterize the <i>GR</i> parameter, which are the Quaternary aquifer and its overlaying and underlying layers. Thirty four <i>VES</i> points already carried out in the study area with Schlumberger array, and a maximum half current spacing <i>AB/2</i> of 500 m are used in this research. The one dimensional (<i>1D)</i> quantitative interpretations of those <i>VES</i> show that the first overlaying layer resistivity and thickness ranges are of 0.6–212 <i>Ω.m</i> with an average value of 56 <i>Ω.m</i>, and 1.1–28 m with an average value of 4.64 m respectively. The second Quaternary aquifer layer resistivity and thickness ranges are of 4.3–43 <i>Ω.m</i> with an average value of 15 <i>Ω.m</i>, and 4.5–59.2 m with an average value of 27.5 m respectively. The third underlying layer resistivity and thickness ranges are of 1.7–79.5 <i>Ω.m</i> with an average value of 11.77 <i>Ω.m</i>, and 14.3–283 m with an average value of 82.1 m respectively.<i> The (GR</i>) parameter shows also that the three modeled hydrological units are averagely vulnerable to contaminations.</p><p>Two resistivity reflection coefficients <i>K1</i> and <i>K2 are also developed and used to follow</i> the resistivity distribution trends of the three mentioned modeled hydrological units, where an alternating sequence of clay, alluvial and sandy components of ramel aswad, and marly clay is decided. <i>GR</i> parameter can be therefore employed worldwide to follow the electrical resistivity variations with depth, for several useful applications, such as assessing aquifer vulnerability to contamination, mapping the geologic sequence with depth for evaluating the subsurface for mineral explorations and for locating the engineering sites.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"71 - 96"},"PeriodicalIF":1.4,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879651","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}

{"title":"Ring current local time dependence during geomagnetic storms using equatorial Dst-proxies","authors":"Santiago Pinzon-Cortes,&nbsp;Natalia Gómez-Pérez,&nbsp;Santiago Vargas Domínguez","doi":"10.1007/s40328-024-00459-6","DOIUrl":"10.1007/s40328-024-00459-6","url":null,"abstract":"<div><p>In this paper, we calculate Local Disturbance indices (LDi) using data from two equatorial observatories (Ascension ASC and Fúquene FUQ) to use them as Disturbance Storm-time (Dst) index proxies. We find that the LDi response to geomagnetic storms is different depending on the observatory’s local time at the storm onset. In order to explore this local time influence on the measurements on the ground at low latitudes, we build new proxies using two observatories located at approximately the same longitude, in order to balance measurements in the north and south averaging meridional and measuring only zonal variations. The average of the longitude pairs and Dst-index proxies from single observatories exhibit strong correlation to the Dst index (<span>(ge )</span> 0.88) during active periods and a moderate correlation (<span>(le )</span> 0.5) during quiet periods. We find that the storm intensity is associated with local time. We confirm that the fastest variation in the geomagnetic field during the storm is recorded between dusk and midnight, while the region between dawn and noon records more moderate variations, sometimes missing the storm effects altogether. Our results show an azimuthal asymmetry of the magnetospheric ring current, becoming most intense on the night side of the dusk terminator during active periods. We propose a new configuration for local time Dst proxies including the use of equatorial observatories. This will get insights of the evolution of storms in an area where there are limited geomagnetic observatories.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"97 - 114"},"PeriodicalIF":1.4,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40328-024-00459-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geophysical characterization for dolerite dykes (dimension stone) reserves exploration using electrical resistivity tomography (ERT) in Shergarh Oghi, Mansehra, Pakistan","authors":"Irfan Raza,&nbsp;Hashmat Ullah,&nbsp;Perveiz Khalid,&nbsp;Muhammad Zeerak Iqbal,&nbsp;Sania Rasheed,&nbsp;Muhammad Irfan Ehsan","doi":"10.1007/s40328-025-00465-2","DOIUrl":"10.1007/s40328-025-00465-2","url":null,"abstract":"<div><p>Due to rapid increase in demand of building stones the geophysical prospecting of potential dimension stone (Dolerite Dykes, commonly known as “Black Granite”) deposits is of great significant. Dimension stone is widely distributed in the Hazara Valley of KPK, Pakistan. The primary aim is to characterize subsurface structural features and resistivity values crucial for dimension stone deposits, guiding the selection of viable mining zones. Employing electrical resistivity tomography (ERT), an electric current was introduced through electrodes embedded in the ground, demonstrating efficiency, cost-effectiveness, and data coverage. Conducted with the SuperSting R8/IP/SP instrument from AGI USA, the survey utilized a dipole-dipole array with 56 electrodes spaced at 20-meter intervals along eleven profiles. The 2D-ERT technique, or resistivity imaging, employed EarthImager software from AGI USA for data inversion, revealing distinctive low and high resistivity signatures along all profiles. Shallow high resistivity values indicated boulder material, while shallow low resistivity values pointed to subsurface dolerite dyke material. Profiles exhibited deep high resistivity values, suggesting subsurface granitic soft bedrock. EarthImager™ 3D software enabled inferred resource estimations, identifying a volume of 4,349,744 cubic meters and a total tonnage of 13.04 million tons for dolerite (dimension stone) material. The 3D-ERT inversion results further enhanced the understanding of the spatial distribution of the dolerite deposits, providing high-resolution images of subsurface resistivity, which facilitated the identification of economically significant zones. Based on geophysical study it is recommended to drill six confirmatory boreholes of a minimum 150 m depth to assess and confirm dolerite dyke zones/anomalies for future mine planning in the study area.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"53 - 69"},"PeriodicalIF":1.4,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879706","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}

{"title":"Response of low-latitude lower ionosphere during solar flare events over the complete solar cycle 24","authors":"Gaurish Tripathi,&nbsp;Ashutosh K. Singh,&nbsp;Prashant Singh,&nbsp;Abhay Kumar Singh","doi":"10.1007/s40328-025-00461-6","DOIUrl":"10.1007/s40328-025-00461-6","url":null,"abstract":"<div><p>The lower ionosphere of Earth is greatly impacted by solar flares. During a solar flare event, a sudden enhancement in X-ray flux leads to additional ionization, which increases electron density in the lower ionosphere. In this paper, we first investigated time the behaviour of lower ionosphere during solar flare events (SFE) over the complete solar cycle 24 during the years 2011 to 2018 by using amplitude measurement of very low frequency (VLF) waves and GOES 0.1–0.8 nm X-ray flux. The fixed frequency (19.8 kHz) VLF wave transmitted from the NWC-transmitter, Australia is observed at our low-latitude station Varanasi (geom. lat. 14^o 55^/ N, geom. long. 154^o E), India. The amplitude enhancements associated with solar flares are characterised by the two traditional Wait parameters, virtual reflection height (H^/ in km) and the sharpness factor (<i>β</i> in km^− 1) i.e. electron density gradient. These empirically determined values of H^/ and β were employed in Long Wave Propagation Capability (LWPC) to predict VLF amplitude perturbations induced by the solar flare throughout a wider frequency range than was observable. It is found that the sharpness factor increases with the increasing strength of solar flares, but the virtual reflection height decreases. These observations show a decrease in H^/ from 78 km to 62 km and an increase in <i>β</i> from 0.34 km^− 1 up to a ‘saturation’ level of 0.51 km^− 1. A comparative study of these parameters during different phases of the solar cycle shows that during the rising phase of the solar cycle, <i>β</i> is found to be lower. In contrast, during the declining phase, its value is higher. Also, H^/ decreases more during the decreasing phase of the cycle than during the rising phase. During the peak of the solar cycle, H^/ and β values are found to lie between rising and decreasing phase values, although more dispersed. This indicates that the lower ionosphere behaves differently during different phases of the solar cycle.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"115 - 136"},"PeriodicalIF":1.4,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879655","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}

{"title":"Combined effects of terrain corrections and deterministic modifiers on the Stokes-Helmert geoid over sophisticated topography","authors":"Ramazan Alpay Abbak,&nbsp;Ropesh Goyal,&nbsp;Aydin Ustun,&nbsp;Sevda Olgun","doi":"10.1007/s40328-025-00460-7","DOIUrl":"10.1007/s40328-025-00460-7","url":null,"abstract":"<div><p>This study focuses on analysing the impact of deterministic modifications of the Stokes kernel and terrain correction methods for precise geoid determination using the Stokes-Helmert method over a sophisticated topography. Three deterministic modification methods of Stokes’s kernel (Wong-Gore, Vaníček-Kleusberg, and Featherstone-Evans-Olliver) are tried to minimize the truncation error emanating from the non-availability of gravity data all over the Earth by utilizing two independent satellite only global geopotential models. In parallel to the modified Stokes kernel functions, two terrain correction techniques, i.e., spatial-spectral combined method with mass-prisms and spatial method with mass-cylinders, have also been examined to assess their combined effects on geoid heights over the Konya Closed Basin in Türkiye. The developed geoid models are validated with GNSS-levelling data and inter-compared pixel-wise. The numerical results show that although the overall statistical values depict consistent precision for various combinations of TCs, Stokes kernel modifiers, and GGMs, a holistic validation-comparison analysis reveals significant variations in view of the cm-precise geoid.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"29 - 51"},"PeriodicalIF":1.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879708","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}

{"title":"Predictive diagnosis of El Niño based on empirical sea level anomaly forecasts","authors":"Małgorzata Świerczyńska-Chlaściak,&nbsp;Tomasz Niedzielski,&nbsp;Bartłomiej Miziński","doi":"10.1007/s40328-024-00457-8","DOIUrl":"10.1007/s40328-024-00457-8","url":null,"abstract":"<div><p>The aim of this paper is to present the skills of two statistical models in anticipating the development of El Niño based on sea level anomaly (SLA) forecasts with lead time up to 12 weeks. The models are: (1) the polynomial-harmonic model (PH) combined with the threshold autoregressive model (TAR), known as the PH+TAR, and (2) PH integrated with the multivariate autoregressive model (MAR), referred to as PH+MAR. Five powerful El Niño events are considered: 1997/1998, 2002/2003, 2006/2007, 2009/2010, 2015/2016. The performance of the prediction models is calculated in specific locations in the equatorial Pacific, i.e. centres of Niño 1+2, Niño 3, Niño 3.4 and Niño 4 regions. It is found that the SLA predictions hitting the El Niño peaks reveal different accuracy for dissimilar El Niño events, with the most skillful prognoses for El Niño 1997/1998. Two specific regions are identified in which the model performance fulfils the assumed accuracy limit of 5 cm, namely the Niño 1+2 and Niño 4 regions. In addition, the PH+MAR model performed better than the PH+TAR solution.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"15 - 27"},"PeriodicalIF":1.4,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40328-024-00457-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural based joint inversion of magnetometry and DC resistivity data through cross gradient constraint","authors":"Ali Dehghan Mongabadi,&nbsp;Ahmad Zarean Shirvanehdeh,&nbsp;Aynur Nasseri,&nbsp;Rashed Pourmirzaee","doi":"10.1007/s40328-024-00456-9","DOIUrl":"10.1007/s40328-024-00456-9","url":null,"abstract":"<div><p>When separate inversion of geophysical data set cannot result in desirable reconstruction of subsurface anomalies, joint inversion of geophysical methods is one of the most common ways to overcome the problem. Cross gradient based joint inversion is the only technique allowing to execute joint inversion of magnetometry and DC resistivity data. In this paper, joint inversion of magnetometry and DC resistivity, based on nonlinear equations, is carried out. Smoothness and product of depth weighting and compactness are manipulated as model weighting functions for DC resistivity and magnetometry methods, respectively. The joint inversion is first applied to noise-free synthetic data of a thin dyke to evaluate its productivity which shows that separate inversion of DC resistivity leads to poor reconstruction of the thin dyke, while magnetometry recovers the dyke model very well. After the joint procedure, the magnetic method plays the role of an efficient constraint through cross gradient to improve the resistivity model about satisfactory recovery of the thin dyke. Then, usefulness of the joint inverse algorithm is tested in the presence of the noise demonstrating its productivity for noise levels up to 5%. Ultimately, the joint inversion algorithm is utilized for the real data collected over a relatively thin dyke in Morgenzon Farm in South Africa successfully.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"1 - 14"},"PeriodicalIF":1.4,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879502","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}