Direct ore-mineral U-Pb geochronology of scheelite (CaWO₄), cassiterite (SnO₂), and wolframite ([Fe,Mn]WO₄) using recently-developed reference materials led to new ore-genesis insights for multiple worldwide W-Sn/rare metal deposits. Scheelite from the Yellow Pine epithermal Au-W-Sb deposit in Idaho, USA was age dated using U-Pb via isotope dilution thermal ionization mass spectrometry (TIMS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). These analyses provided both the first age constraints on the tungsten mineralization (ca. 57 Ma) and a scheelite U-Pb reference material (NMNH-107667; 57.52 ± 0.22 Ma). The data reveal ore mineralization occurred in numerous discrete pulses during crustal uplift, which contrasts with the previous two-mineralization-event model.

The Yellow Pine scheelite reference material enabled U-Pb scheelite geochronology via LA-ICP-MS for multiple other deposits worldwide; namely, the polyphase stratabound scheelite-ferberite mineralization hosted within Fe-rich magnesite zones and marbles in two locations around Mount Mallnock, Austria. Two unexpected but geologically meaningful age dates (294 ± 8 Ma) for Mallnock West and (239 ± 3 Ma) for Mallnock North revealed for the first time that ore mineralization occurred during an extensional geodynamic setting as part of the breakup of Pangea, as opposed to the previous model invoking the older compressional tectonics of the Variscan orogeny.

Combining direct-ore geochronology methods for several ore minerals was particularly powerful for Sn- and W-bearing deposits in southeast Australia. A U-Pb cassiterite age date (435 ± 2 Ma) revealed the tin-bearing lithium pegmatites of the Dorchap Dyke Swarm are ca. 15 Ma older than some previous estimates suggesting mineralization was related to the earliest magmatic activity recorded in the Wagga-Omeo Metamorphic Belt. Additionally, a new U-Pb wolframite age date (395 ± 5 Ma) for the Womobi polymetallic (W-Mo-Bi) deposit is ca. 21 million years younger than the host Thologolong granite, suggesting the granite was a passive host that was mineralized by a concealed intrusion. Both instances revealed mineralization ages that were significantly different than previously accepted. More widespread application of these increasingly diverse, direct-ore geochronology methods stand to replace uncertain spatial or textural associations, thereby providing an opportunity to significantly improve ore genesis models.

How to cite: Wintzer, N., Holm-Denoma, C., Altenberger, F., and Waugh, S.: W-Sn Ore-Mineral Geochronology: New Ages Improve Genesis Models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5245, https://doi.org/10.5194/egusphere-egu25-5245, 2025.

The Vemula-Velpula hydrothermal barite deposit is hosted by mafic dykes (ca. 1850 Ma. [1]) intruding into the uppermost part of about 1900 m thick carbonate strata of the Vempalle Formation (ca. 2000 Ma. [2]) in Cuddapah basin and occurs as fracture-fill and breccia-fill veins. The veins dominantly consist of barite with minor quartz. The host mafic rock has undergone various extents of hydrothermal alteration, due to which the primary calcic plagioclase-clinopyroxene assemblage is altered to albite and clinochlore, along with the introduction of secondary epidote, quartz, and calcite. The wide range in Ba concentration of mafic rock (68 to 3012 ppm) associated with the barite mineralization indicates that Ba was mobilized and subsequently leached from the mafic rock by the hydrothermal fluid during this alteration event. The δ³⁴S values of barite range from +16.19 to +23.24‰ which falls within the range of δ³⁴S value of +10 to +30‰ estimated for Proterozoic seawater [3]. At shallow crustal depth where this deposit was formed, direct participation of seawater is unlikely and therefore basinal brine is inferred to be the source of sulphate ion required for barite mineralization. Primary aqueous biphase fluid inclusions in barite have homogenization temperatures ranging from 180 to 300 °C, with most of them clustering in the range 220-250°C, and salinities ranging from 2.4 to 25.8 wt.% NaCl equivalent. The first ice melting temperature of these inclusions was measured between -55 and -37°C, broadly pointing towards an H₂O-NaCl-CaCl₂ fluid system. Petrography and microthermometric data of fluid inclusions indicate the involvement of two fluids of different salinities, which, upon mixing and cooling, led to barite precipitation.

This research work was funded by SERB, New Delhi (Scheme No. CRG/2019/001015).

References

[1] Chakraborty K. et al. (2016), Journal of the Geological Society of India 87, 631–660.

[2] Rai A.K. et al., (2015), Journal of the Geological Society of India 86, 131–136.

[3] Strauss H (1993) Precambrian Research 63(3–4), 225–246.

How to cite: Devanand Sreekala, D. and Muthusamy, S. P.: Insight into the genesis of barite deposit in Vempalle Formation, Cuddapah basin, India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4666, https://doi.org/10.5194/egusphere-egu25-4666, 2025.

Abstract.

The Isiro and Ngayu belts in northeastern Democratic Republic of Congo (DRC) are part of the Congo Craton and among the most poorly known Archean terrains worldwide. These belts consist of metavolcanic and metasedimentary rocks surrounded or intruded by granitoid rocks. minimum age of deposition for the supracrustal formations is defined at ca 2633 Ma (e.g. Allibone et al., 2020), whereas the granitoids were dated between 3200 Ma and 2530 Ma (Allibone et al., 2020; Turnbull et al., 2021) and are strongly deformed with variable proportions of mafic enclaves at outcrop scale (Turnbull et al., 2021). Both Isiros and Ngayu belts host important gold deposits, but the genetic relationships between gold mineralization, deformation and the diverse host rocks remain ambiguous. In this context, the work we present here is part of a multidisciplinary approach, combining the processing of satellite images and field observations using GIS to map the structural lineament that may control gold mineralization in the region. The results show that the strains are large, marked by NW-SE lineaments at low angle to the belt strikes and combined with a secondary ENE-WSW brittle structure. The overall structural pattern, together with the existence of artisanal gold mining in the area, emphasizes that gold mineralization is largely controlled by structures localization along the greenstone belts.

Key words: Congo craton, gold mineralization, field observations, satellites images, structural lineaments.

Reference

Allibone, A., Vargas, C., Mwandale, E., Kwibisa, J., Jongens, R., Quick, S., Komarnisky, N., Fanning, M., Bird, P., MacKenzie, D., Turnbull, R., Holliday, J., 2020. Chapter 9: Orogenic Gold Deposits of the Kibali District, Neoarchean Moto Belt, Northeastern Democratic Republic of Congo, in: Sillitoe, R.H., Goldfarb, R.J., Robert, F., Simmons, S.F. (Eds.), Geology of the World’s Major Gold Deposits and Provinces. Society of Economic Geologists, p. 0. https://doi.org/10.5382/SP.23.09

Turnbull, R.E., Allibone, A.H., Matheys, F., Fanning, C.M., Kasereka, E., Kabete, J., McNaughton, N.J., Mwandale, E., Holliday, J., 2021. Geology and geochronology of the Archean plutonic rocks in the northeast Democratic Republic of Congo. Precambrian Research 358, 106133. https://doi.org/10.1016/j.precamres.2021.106133

How to cite: Birimwiragi Namogo, D., Martial Akame, J., Mbuluyo, M., Debaille, V., Mango Itulamya, A. L., and Hubert-Ferrari, A.: Geology of the Isiro-Ngayu gold-bearing region, western belts of the Kibali granite-greenstone superterrane in the northeastern Congolese craton, Democratic Republic of Congo, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13796, https://doi.org/10.5194/egusphere-egu25-13796, 2025.

Abstract

Urban surface dust and soils serve as a primary source and reservoir of metals that substantially impact human health and urban ecosystems. This study investigates the impact of metal contamination on urban surface soils from diverse land-use locations and their potential risk to human health in Jammu City, India. A total of fifteen surface soil samples were collected to evaluate the total metal concentration (As, Cu, Fe, Mn, Ni and Zn), Contamination Factor (CF), Geo-accumulation Index (Igeo), Pollution Load Index (PLI), and Potential Ecological Risk Index (PERI). The research findings of this study revealed significant variation in metal concentration. In comparison to Upper Continental Crust (UCC, taken as background here), the average concentration of Fe and Mn is lower across all locations, whereas As, Ni, Cu, and Zn are significantly higher over all locations. Elevated levels of Fe and Mn were observed higher near samples collected from industrial zones while Ni, As, Cu and Zn showed wider distribution throughout the study area. Apart from all metals, high As content was observed at near-construction and high-traffic interactions. Higher CF (CF > 6) and PLI values in surface soil samples revealed high contamination of As, Cu, Ni and Zn due to intensive industrial and vehicular emissions in the study area. Igeo values in surface soil samples indicated severe contamination of As, Cu, Ni and ZN in the study area, while Fe and Mn showed no contamination. PERI assessment in surface soil samples revealed extremely high ecological risk for As and Cu in Jammu City. Risk index values indicated that 40% of surface soil samples carried a very high risk (RI > 600) of metal contamination in the study area. The overall findings advised that industrial, transportation, and construction activities need to be improved to protect the region's environment and public health.

Keywords: Heavy metals, geo-accumulation index (IGeo), risk assessment, roadside dust.

How to cite: Gorka, R. and Kumar, R.: Spatial Distribution and Contamination Levels of Heavy Metals (Fe, Mn, Ni, Cu, As, and Zn) in Urban Topsoils of Jammu City, India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14122, https://doi.org/10.5194/egusphere-egu25-14122, 2025.

The Residual Terrain Modeling (RTM) technique is commonly used to recover short-wavelength gravity field signals. However, classical gravity forward modeling methods for RTM gravity field determination face challenges such as series divergence, inefficient computation, and errors induced by tree canopy in Digital Elevation Models (DEMs). In this study, deep learning methods are employed to enhance the quality of the computed RTM gravity field. Experiments are conducted at the Wudalianchi airborne gravity gradiometer test site, which provides a large volume of precise gravity measurements. The Random Forest method is used to estimate and correct tree canopy height errors in DEMs. A fully connected deep neural network (FC-DNN) is introduced to efficiently calculate the RTM gravity field. Additionally, to improve the network’s generalization capability, a novel terrain information fusion regularization method is applied to create an Improved FC-DNN with a refined loss function. The accuracy, computational efficiency, and generalization performance of the deep learning method are evaluated and compared in the Wudalianchi volcanic region. The results demonstrate a significant improvement in the accuracy of the RTM gravity field when based on tree canopy-corrected DEMs. The RTM gravity fields determined using both FC-DNN and Improved FC-DNN achieve mGal-level accuracy, with a remarkable 10,000-fold increase in computational efficiency compared to the classical Newtonian integration method. The Improved FC-DNN exhibits superior generalization, with accuracy enhancements ranging from 7% to 21% compared to the standard FC-DNN.

How to cite: Yang, M., Zhang, B., Wang, L., Feng, W., and Zhong, M.: Deep learning in RTM gravity field modeling: A case study over Wudalianchi area, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20320, https://doi.org/10.5194/egusphere-egu25-20320, 2025.

Zenith Total Delay (ZTD) is a crucial parameter for understanding the effects of atmospheric conditions on satellite signals, constituting a fundamental aspect of precision positioning and atmospheric modeling applications. Traditional methods for ZTD estimation, including GNSS observations, numerical weather prediction models, and interpolation techniques, encounter critical limitations such as generalization constraints, sparse data availability, insufficient spatial coverage, high computational costs, and limited adaptability to dynamic atmospheric changes. Deep learning techniques provide substantial benefits, including processing large and complex datasets, enabling dynamic modeling, and delivering rapid and accurate estimations.

This study integrates real-time GNSS observations with high-resolution atmospheric reanalysis data from the ERA5 dataset to develop deep learning-based methods for ZTD estimation. GNSS data were sourced from 17 IGS tropospheric stations strategically selected to represent diverse geographic and climatic conditions. These stations supplied ZTD values and their temporal variations at 5-minute intervals, spanning February 2023 to January 2024. ERA5 data, offering hourly atmospheric parameters, necessitated the alignment of GNSS temporal resolution with ERA5 for spatial modeling. The spatial distribution of GNSS data was optimized using interpolation techniques to enhance the quality of inputs for deep-learning models.

The findings highlight the potential of deep learning techniques to enhance ZTD estimation processes. Future research will focus on integrating additional datasets, such as InSAR, to achieve higher spatial resolution and improved accuracy. Moreover, advanced deep learning architectures, including attention mechanisms, will be investigated to refine estimation methods and broaden their applications in atmospheric and geospatial studies.

How to cite: Tekin Ünlütürk, N. and Bak, M.: Deep Learning Approaches for Zenith Total Delay Estimation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15605, https://doi.org/10.5194/egusphere-egu25-15605, 2025.

Geodetic VLBI (Very Long Baseline Interferometry) currently consists of two observing networks (legacy S/X and broadband VGOS). Heretofore, the two networks have run rather independently, which is non-ideal. There have been several attempts to combine observations from both networks at sites with co-located antennas using either conventional local-tie surveys or VLBI tie-sessions between S/X and VGOS, or both. Unfortunately, the number of sites with co-located VLBI antennas is rather limited, which hampers progress. To overcome this problem, we proposed an approach, the so-called mixed-mode VLBI tie session, that does not require to have co-located VLBI antennas. Instead, mixed-mode sessions have the S/X and VGOS networks observed simultaneously as a single geodetic VLBI technique to thus obtain global ties between the two networks. Two of the sessions observed in 2020 were already included in the ITRF2020 combination. We hypothesize that the global-tie approach helps preserve the geometry of the networks when aligning with the state-of-art ITRF2020 frame. In this presentation, we will describe the observed mixed-mode sessions, detailing scheduling strategies, correlation techniques, and geodetic processing methods used. We will also demonstrate how mixed-mode sessions can help realize a stable global geodetic reference frame such as the ITRF.

How to cite: Mondal, D. R., Elosegui, P., Ruszczyk, C., Lemoine, F., and Behrend, D.: Global VLBI ties using mixed-mode sessions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12533, https://doi.org/10.5194/egusphere-egu25-12533, 2025.

A Global Geodetic Observing System (GGOS) affiliate is an organization or entity that collaborates with the Global Geodetic Observing System (GGOS) to enhance the global geodetic infrastructure and support the objectives of GGOS in a region.
With this goal, a GGOS affiliate was created to enhance geodetic infrastructure and scientific collaboration across the Iberian Peninsula and the Atlantic region. It is called GGOS IberAtlantic. This project focuses on improving the accuracy and reliability of geospatial data through the co-location and integration of geodetic space techniques to support various scientific and practical applications, including global reference frame maintenance, climate change monitoring, natural hazard assessment, in the perspective of a sustainable development. GGOS IberAtlantic aims to establish a robust network of geodetic stations, facilitate high-accuracy data collection, and promote international cooperation among geodetic institutions, contributing to a better understanding of Earth's dynamic processes. It is also focused on supporting decision-making in the area and bringing geodesy closer to society, specially to young scientists.
The upcoming presentation will outline the steps taken to establish the GGOS IberAtlantic group, as well as its future directions and objectives.

Acknowledgment. This presentation was supported partially by Spanish Project PID2020-119383GB-I00 funded by Ministerio de Ciencia e Innovación (MCIN/AEI/10.13039/501100011033)

How to cite: Azcue, E. and Ferrándiz Leal, J. M. and the GGOS IberAtlantic Governing Board: GGOS IberAtlantic Affiliate: Bringing Geodesy Closer to Society across the Iberian Peninsula and the Atlantic region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17154, https://doi.org/10.5194/egusphere-egu25-17154, 2025.

The Geophysics Section of the Royal Institute and Observatory of the Navy (ROA) is structured into three main services: Seismology, Geomagnetism, and Space Geodesy, in addition to an auxiliary Meteorology service and participation in maritime scientific campaigns. Since its foundation, the ROA has played a pioneering role in Spain, being a member of the Spanish Commission of Geodesy and Geophysics and collaborating with international institutions across all its fields of activity, such as ILRS, IGS, INTERMAGNET, and GEOFON, as well as organizations like NASA and ESA, among others.

The Geomagnetism Service, established in 1879, studies the Earth's magnetic field and its variations to conduct scientific research. After several relocations due to electromagnetic interference, the current geomagnetic observatory is located at Cortijo de Garrapilos (Cádiz) and has been a member of INTERMAGNET since 2006. The Seismology Service dates back to 1898, when one of the 12 seismographs of the first global seismic network, promoted by geologist John Milne, was installed at the ROA. The current infrastructure is distributed across Spain and North Africa, including a short-period network for regional seismicity in the Gulf of Cádiz and the Alboran Sea, long-period stations for global seismicity, and the international Western Mediterranean network, in which prestigious institutions such as UCM and GFZ participate. The ROA has been involved in space geodesy with artificial satellites since the early days of the space era, starting just one year after the launch of the first SPUTNIK (1958) with the Baker-Nunn camera. This technique was followed by laser ranging (SLR) in 1975, when a station capable of tracking collaborative satellites was installed. By 1980, the station was exclusively operated by ROA personnel. Since then, the station has undergone constant upgrades to maintain a high level of operability. Today, it contributes to national and international tracking networks such as ILRS-EUROLAS and EU SST-S3T. Additionally, the ROA adopted GPS in the 1980s for geodetic studies and currently manages a GNSS network comprising 17 permanent stations spanning the southern Iberian Peninsula and North Africa. Maritime campaigns include studies in the Spanish Exclusive Economic Zone (EEZ), with objectives such as hydrographic surveys and geophysical exploration for seabed characterization. Since 1987, the ROA has also participated in Antarctic campaigns.

The Geophysics Section of the ROA combines tradition and advanced technology to contribute to the understanding of the Earth and space, consolidating its position as a national and international benchmark in the study of geophysical and geodetic processes. Evidence of this includes recent or ongoing scientific work over the past years: four doctoral theses (three of them in progress), various articles in high-impact journals, participation in numerous scientific projects, and extensive contributions to conferences. In this way, the ROA, through the Geophysics Section, fosters collaboration in geodesy through its active participation in international networks, addressing global scientific and societal challenges with cutting-edge technology and a multidisciplinary approach.

How to cite: Rodriguez Collantes, D., Sánchez Piedra, M. Á., Cabieces Díaz, R., and Fiz Barreda, J.: Scientific Legacy and Current Contributions of the Royal Institute and Observatory of the Spanish Navy: Impact on Geophysics, Geodesy, and other Scientific and Social Fields., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19802, https://doi.org/10.5194/egusphere-egu25-19802, 2025.

Anelasticity is a type of rheology intermediate between elasticity and viscosity, responsible for rock’s transient creep behaviour. Whether to consider anelasticity in geodynamic processes operating outside the seismic frequency band which likely involve transient mantle creep is still under debate. Here, we focus on the geodynamic process of ocean tide loading (OTL), namely the deformational response of the solid Earth to the periodic ocean water-mass redistributions caused by astronomical tides. By analysing high-precision Global Positioning System (GPS) data from over 250 sites in western Europe and numerical OTL values from advanced three-dimensional Earth models, we unambiguously demonstrate anelastic OTL displacements in both the horizontal and vertical directions. This finding establishes the need to consider anelasticity in geodynamic processes operating at sub-seismic timescales such as OTL, post-seismic movement, and glacial isostatic adjustment (GIA) due to rapid ice melting. Consequently, to construct a uniform viscoelastic law for modelling Earth deformations across multiple timescales anelasticity must be incorporated. Our best-fitting anelastic models reveal the shear modulus in Earth’s upper mantle to be weaker at semi-diurnal tidal frequencies by up to 20% compared to the Preliminary Reference Earth Model (PREM) specified at 1 Hz, and constrain the time dependence of this weakening.

How to cite: Huang, P., Penna, N. T., Clarke, P. J., Klemann, V., Martinec, Z., and Tanaka, Y.: Signature of mantle anelasticity detected by GPS ocean tide loading observations , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9320, https://doi.org/10.5194/egusphere-egu25-9320, 2025.

The Second Earth Orientation Parameters Prediction Comparison Campaign (2nd EOP PCC) aimed to evaluate and compare various methods of Earth Orientation Parameters (EOP) predictions. One of the goals of the 2nd EOP PCC was to prepare a combination of the predictions to obtain one robust and accurate solution for forecasts of individual parameters. This presentation focuses on identifying the most reliable and accurate combination of predictions for polar motion (PMx, PMy), universal time variations (UT1-UTC), and length of day (LOD) among the methods tested during the 2nd EOP PCC.

Two types of experiments were designed for this study: "operational" combinations tailored to real-time comparisons and practical application and "final" combinations designed for comprehensive analysis. Boths approaches incorporated six methods for handling outlier predictions, ranging from no filtration to progressively stricter criteria using the σ+β method (with α values ranging from 5 to 1). All experiments cover the period of 2nd EOP PCC (from September 1, 2021, to December 31, 2022), and each approach includes 70 10-day predictions.

The results show that combining various submissions generally enhances stability and accuracy of EOP forecasts. The σ+β criterion with α = 1 achieved the smallest Mean Absolute Prediction Error, indicating high accuracy of prediction. However, this method of eliminating outliers forecasts is the most restrictive, as it excludes a significant number of predictions. In contrast, operational combinations without filtering proved more practical for real-time applications, albeit with slightly higher errors.

The findings underscore the importance of tailoring combination strategies to specific goals—whether prioritizing maximum accuracy or practical applicability. This research highlights the benefits of prediction combination methods in improving EOP forecasts, offering a foundation for further development of operational strategies and expanding their use in geophysical and astronomical applications.

How to cite: Michalczak, M., Śliwińska-Bronowicz, J., Wińska, M., Partyka, A., Ligas, M., and Nastula, J.: Exploring various approaches to combine Earth Orientation Parameter (EOP) predictions gathered during the Second EOP Prediction Comparison Campaign (2nd EOP PCC), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9658, https://doi.org/10.5194/egusphere-egu25-9658, 2025.

This study introduces a methodology designed to enhance the accuracy of Celestial Pole Offset (dX, dY) prediction, with a focus on a short-term forecast horizon (up to 30-days). IERS EOP final data as well as those published by JPL are used as input for the  prediction algorithms. The prediction procedure is consistent, in the sense that, it does not rely on any external data to fill any latency gaps in the final IERS product. This is handled within the prediction routine itself by enlarging the forecast horizon to the gap filling horizon and proper forecast horizon. In this way, the presented methodology is ready to use under operational settings what makes it well suited for real time applications. Such an approach enables also to asses prediction capabilities of the methods in offline experiments whilst maintaining the operational settings. JPL CPO data serves as supplementary series for prediction and adjusting using Deming regression to align it  with IERS CPO values (attempt to assess fixed and proportional biases between series). The prediction strategy applies also the Whittaker-Henderson smoother to IERS CPO series, which after smoothing is treated as an additional source of information in the prediction process. Separate predictions based on JPL, IERS and smoothed IERS series are also averaged in different combinations giving rise to ensemble data-based prediction model. In this way we show that the overpredictive and underpredictive characteristics of specific input data, even with the application of a single prediction method, can result in a more precise and accurate final forecast. The presented approach was tested against the results obtained within the course of the 2^nd EOPPCC, as well as other contemporary studies. This presentation includes also a comparison of performance of the method in reference to different series, i.e., IERS EOP 14 C04 and IERS EOP 20 C04.

How to cite: Ligas, M., Michalczak, M., Belda, S., Ferrándiz, J. M., Karbon, M., and Modiri, S.: Enhanced Celestial Pole Offset forecast via combination of different data sources, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11708, https://doi.org/10.5194/egusphere-egu25-11708, 2025.

The need to improve Earth rotation theories and models in a consistent and accurate
manner is currently widely recognized. Several researchers and groups at different
institutions have been working on this problem using quite different approaches, either
from the theoretical or computational perspective.
A potential source of the loss of accuracy of celestial pole offsets can be due to the
mismodeling of the planetary component of the IAU2000 nutation series. In fact, as
recognized in Ferrándiz et al. (2018), this component is actually based on a rigid-Earth
solution and does not include the Oppolzer terms that are significantly affected by the
Earth non-rigidity.
Such hypothesis was showed to be realistic by adjusting directly the amplitudes of a
small number of nutation periods of strictly planetary origin that could be reasonably
well separated by analyzing the series of VLBI observations. The results provide
significant fittings and the WRMS was successfully decreased by amounts comparable
to those achieved with lunisolar amplitude rescaling. A further step in this direction
requires the consideration of theoretical developments for the amplitudes of the non-
rigid Earth planetary nutations.
In this contribution, we present preliminary results considering the analytical formulae
of such planetary amplitudes for a two-layer earth model including dissipation effects at
the core-mantle boundary and anelasticity, obtained from a Hamiltonian method. Their
performance is assessed using several series of VLBI observations, with satisfactory
results, and is placed in the general context of the improvement of the precession and
nutation models sought by the IAG and the IAU.
Acknowledgment. This research was supported partially by Spanish Projects PID2020-119383GB-I00 funded by
Ministerio de Ciencia e Innovación (MCIN/AEI/10.13039/501100011033); SEJIGENT/2021/001, funded by
Generalitat Valenciana; and the European Union—NextGenerationEU (ZAMBRANO 21-04).

How to cite: Zerifi, A. Z., Ferrándiz, J. M., Escapa, A., Baenas, T., Juárez, M. A., Belda, S., and Karbon, M.: Performance of a new set of analytical corrections to planetary nutations: preliminary results and outlook, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13099, https://doi.org/10.5194/egusphere-egu25-13099, 2025.

The relationship between the length of day (LOD) and the El Niño-Southern Oscillation (ENSO) has been extensively studied since the 1980s. LOD represents the negative time derivative of UT1-UTC, directly proportional to the Earth Rotation Angle (ERA), a key Earth Orientation Parameter (EOP).

ENSO is a climate phenomenon occurring in the tropical eastern Pacific Ocean that primarily impacts the tropics and subtropics. Extreme ENSO events can lead to severe weather conditions, such as flooding and droughts, across various regions worldwide. ENSO event undergoes a lengthy incubation period, during which the interannual variations in length-of-day (LOD) and atmospheric angular momentum (AAM) are rapidly influenced by the interactions between the ocean and the atmosphere.

The significant characteristics of climate change are the rise of global temperature and sea level, which are driven by ENSO. Interannual oscillations in global mean sea temperature (GMST) and global mean sea level (GMSL) might also impact changes in the Earth’s rotation velocity.

The goal of this study is to explain in more detail connections among the interannual (2-8 years) variations of the LOD, AAM, and different climate indices, like the Southern Oscillation Index SOI, Oceanic Niño Index ONI, GMSL, and GMST. The influence of climate signatures on LOD from January 1976 to December 2024 is assessed using semblance analysis based on continuous wavelet transform. This method evaluates the correlation between climate time series in the time and wavelength domains.

Studying the relationship between LOD, AAM, GMSL, GMST, and ENSO indices enhances our understanding of Earth's dynamic system, improves geophysical models, and increases the precision of applications dependent on accurate timekeeping and Earth rotation measurements.

How to cite: Wińska, M., Śliwińska-Bronowicz, J., Nastula, J., and Staniszewska, D.: Length of the Day changes and climate signatures- their relations in detected ENSO Events, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8007, https://doi.org/10.5194/egusphere-egu25-8007, 2025.

This study investigates the present-day seismotectonic framework of the High Atlas Mountains, Morocco, with a specific focus on the area affected by the devastating Mw 6.8 Al Haouz earthquake of September 8, 2023. Leveraging a high-resolution seismic dataset encompassing over twenty moderate earthquakes (M 3.5-6.8) recorded by regional networks between 2008 and 2024, the research aims to refine earthquake locations and characterize the regional stress field. Initially located using P-wave arrival times, earthquake hypocenters were subsequently relocated using the double-difference method, which yielded more precise locations by minimizing travel-time residuals between pairs of events recorded at common stations. The high degree of agreement between the initial and relocated solutions validates the robustness of the location estimates. Notably, the observed seismicity is confined to shallow crustal depths, consistently shallower than 30 km, corroborating the shallow rupture observed for the Al Haouz earthquake, which occurred at a depth of approximately 31 km. This shallow seismicity suggests a shallow deformation style within the High Atlas.

To determine the state of the present-day tectonic and stress regimes across the western and central segments of the High Atlas, the study uses two complementary approaches: regional seismic moment tensor inversion and P-wave first motion focal mechanism analysis. Fault plane solutions were calculated using P-wave first motion polarities and further constrained through regional moment tensor inversion. The majority of analyzed earthquakes exhibit reverse faulting mechanisms, often with a significant strike-slip component, indicating a complex deformation pattern. Analysis of the principal stress axes (P, B, and T) derived from the focal mechanisms reveals average orientations of 16/189, 39/036, and 08/104 (plunge/azimuth), respectively. Subsequently, tectonic stress tensor properties were derived through inversion of the focal mechanism parameters. The results of this stress inversion indicate a predominantly N-S oriented maximum horizontal stress (σ1) in the Western High Atlas, closely aligned with the faulting style of the Al Haouz earthquake. In contrast, the stress field in the Central High Atlas exhibits a transition to a NW-SE to NNW-NNE orientation of σ1. These spatially varying stress orientations are consistent with independently derived GPS velocities and available neotectonics data, which document ongoing shortening across the High Atlas. This integrated analysis provides a comprehensive understanding of the active tectonic deformation within the High Atlas, shedding light on the complex interplay of faulting styles and stress orientations, and providing crucial insights into the source mechanism and broader tectonic context of the Al Haouz earthquake within the Western High Atlas region.

How to cite: Oujane, B., El Moudnib, L., Zeckra, M., Badrane, S., and Nouayti, A.: Seismotectonics of the Intracontinental High Atlas Mountains, Morocco, Derived from Regional Seismic Moment Tensor Analysis: Insights into tectonics and stress regimes., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9503, https://doi.org/10.5194/egusphere-egu25-9503, 2025.

Tropospheric refraction is one of the major error sources in satellite-based positioning. The delay of radio signals caused by the troposphere ranges from 2m at the zenith to 20m at low elevation angles, depending on pressure, temperature and humidity along the path of the signal transmission. If the delay is not properly modeled, positioning accuracy can degrade significantly. Empirical tropospheric models, with or without meteorological observations, are used to correct these delays but they are limited in accuracy and spatial resolution resulting in up to a few decimeters error in positioning solutions. The present availability of ground-based GNSS networks and the state of the art of GNSS processing techniques enable precise estimation of Zenith Tropospheric Delays (ZTD) with different latency ranging from real time to post-processing.
We present a method for computing ZTD residual fields interpolating, through Ordinary Kriging, the residuals between GNSS-derived and model-computed ZTD at continuously operating GNSS stations. GNSS ZTD estimates, obtained in real time and in PPP mode, are augmented by a multi-prediction model based on a Graph Neural Network model trained using one year of Near Real Time ZTD observations and a model using a polynomial plus harmonic interpolation. A combination strategy is defined to merge GNSS ZTD estimates at sites with the predicted values, where predicted ZTD values act as hole fillers for stations missing from the GNSS network at the current epoch. The residual ZTD field, obtained from PPP/prediction model and ZTD empirical model, is modelled as a random process and for each epoch a variogram is estimated and fitted to characterize the spatial correlation of the process. At a known user location, ZTD value is obtained as the sum of site interpolated ZTD residual and modeled-ZTD value. The algorithm is validated with respect to GNSS ZTD estimates provided by an external provider at a selection of sites not included in the network used to fed the computation. Details about validation and possible improvements will be provided.

How to cite: Basoni, A., Pacione, R., Bagaglini, L., and Lanotte, R.: Real-Time ZTD correction grid based on augmented GNSS network for navigation services, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18280, https://doi.org/10.5194/egusphere-egu25-18280, 2025.

The rapidly changing climate is amplifying both the frequency and severity of extreme weather events in the Azores archipelago, Portugal. Understanding the underlying dynamics of these events is essential for effective mitigation. Atmospheric water vapor data derived from the Global Navigation Satellite System (GNSS) data and reanalysis outputs from an atmospheric general circulation model offer valuable tools for studying the behavior of weather fronts around the Atlantic Ocean environment of the Azores. This research aims to conduct a detailed comparison between GNSS-based measurements and atmospheric reanalysis data, such as those available from ERA/MERRA2, focusing on the detection of small-scale atmospheric structures with high temporal resolution. We utilize atmospheric reanalysis products to decode long-term trends in the frequency and severity of extreme weather events in the Azores. We then apply statistical methods to identify consistencies and differences between these two approaches in capturing atmospheric water vapor patterns. By combining water-vapor estimates from both GNSS data and atmospheric reanalysis, we are able to characterize the dynamics of atmospheric turbulence from small (few meters) to large (few tens of kilometers) scales. 

How to cite: Ramrajvel, N., Mondal, D., Elosegui, P., Paine, S., Mateus, P., and Mendes, V.: Decoding the signal of extreme weather events in the Azores archipelago using GNSS and atmospheric reanalysis products, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13415, https://doi.org/10.5194/egusphere-egu25-13415, 2025.

The neutral atmosphere that extending from the surface of earth to about 80 km overhead is the electrically neutral part (within a certain frequency band which GNSS signals fall) of the atmosphere. There is no doubt that neutral atmosphere has a delaying effect on transmitted radio waves. Spilker (1996) noted that the more precise term of this delaying effect is neutral atmosphere delay, even though this delaying effect has been traditionally referred to as just troposphere delay. At all events, the delaying effect has propagated into satellite observations, and we must deal with it appropriately in order to achieve precise satellite positioning results. There are many geodesists have been making their contributions to treatment of neutral atmosphere delay, and how to get satisfactory supports from numerical weather model data set is one of the efforts making to calibrate this delaying effect more precisely up-to-date. Currently, both Earth observation network and technology have great improvement, which results in wonderful increase of Earth observational data as well as the subsequent numerical weather model data set. Briefly speaking, numerical weather model data set which generally provided by different organizations and/or institutions is a global and/or regional gridded meteorological data set with specific temporal-spatial resolution. Generally, reanalysis data set and forecast data set are usually considered to be the two main data set representations, and they both provide two types of data level, i.e., three-dimensional pressure levels and two-dimensional surface level. The data set contains some usually used meteorological parameters, such as height, temperature, pressure, humidity. With these meteorological parameters, some main terms related to neutral atmosphere delay, such as hydrostatic/wet delay, gradient factors and mapping factors can all be calculated without any difficulty by using computing techniques like raytracing and interpolation. Undoubtedly, the performance of different types of data set that mentioned above in representing neutral atmosphere delay are not all the same. Definitely, some interesting and meaningful comparison results have found and widely propagated by many scholars. In this work, we put more emphasis on evaluation of the forecast data set from neutral atmosphere delay point of view, considering there is an objective fact that satellite positioning industry especially the (near) real-time positioning has vigorous development, in which the calibration of neutral atmosphere delay is required more and more accurate and timely-supported. Besides time-delayed reanalysis data set and time-advanced forecast data set, microwave radiometer data set and radiosonde data set are also employed. The first results show that empirical model such as UNB3 can only state the normal level of delaying effect and the obtained delay values are either larger or smaller; the pressure levels data set performs better than the surface level data set with very high proportion in time domain; even though reanalysis data set generally has good performance, forecast data set can work for the neutral atmosphere delay calibration with relatively satisfactory support in term of accuracy.

This work is supported by the National Natural Science Foundation of China (42304010), the Youth Foundation of Changzhou Institute of Technology (E3-6207-21-060, 31020222007).

How to cite: Wang, M.: First results about evaluation of forecasted numerical weather model data set in view of neutral atmosphere delay, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17506, https://doi.org/10.5194/egusphere-egu25-17506, 2025.

The Crustal Dynamics Data Information System (CDDIS) provides essential support for the Global Geodetic Observing System (GGOS) by operating a data and product archive for the main geodetic techniques.   As GGOS matures and grows, the CDDIS adopts the latest data practices to strengthen its support for the community and ensure quality products are available in a timely manner.  This poster explores the breadth of work done at the CDDIS and provides highlights of the latest developments including new data and product holdings, updates to provide clarity and usability for users, and updates on future works. Statistics on usage will also be provided.

How to cite: Woo, J.: The Crustal Dynamics Data Information System (CDDIS) Updates for 2025, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13924, https://doi.org/10.5194/egusphere-egu25-13924, 2025.

A high-precision Terrestrial Reference Frame (TRF) is essential for accurately monitoring geophysical activities. Currently, India lacks its own Regional Reference Frame (RRF) and relies on the global frame for local applications. With the recent installation of more than 1000 GNSS stations forming the so called CORS (Continuously Operating Reference Stations) network by the Survey of India (SoI), the need for a precise RRF for India has become evident.

The RRF can be realized using either a conventional secular Multi-Year Reference Frame (MRF) or a (geocentric) Epoch-based Reference Frame (ERF). An MRF is realized by aligning the regional network to a global frame such as the ITRF or IGS TRF. However, the accuracy of MRFs diminishes over time as coordinates are extrapolated beyond the observation period using linear velocities. Additionally, MRFs provide limited geophysical information and can’t be utilized with desired accuracy for quasi-instantaneous applications or after large earthquakes.

To address these limitations, this study aims to develop an ERF for the Indian CORS sub-network by adopting the methodology introduced by Kehm (2022) for creating a geocentric ERF in Latin America. The proposed ERF ensures that the frame's origin aligns with the Earth's instantaneous center of mass across all time scales within the observation period.

In this presentation, we will outline the approach to develop the Indian ERF, which involves combining weekly normal equations from global GNSS, SLR, and VLBI networks. Specifically, SLR determines the origin, SLR and VLBI jointly determine the scale, and a homogeneously distributed global GNSS network is used to realise the orientation of the frame. The results will be compared to those obtained using the conventional MRF realization approach. Furthermore, an independent validation strategy will be implemented to evaluate the accuracy of the developed ERF.

How to cite: Kushwaha, R., Bloßfeld, M., Kehm, A., Balasubramanian, N., and Dikshit, O.: Initial Findings on Epoch-Wise Realization of a Regional Reference Frame Using Indian CORS Sub-Network Observations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5046, https://doi.org/10.5194/egusphere-egu25-5046, 2025.