Earth’s gravity field parameters can be derived from the perturbations of Keplerian orbit parameters. For example, even-degree zonal harmonics cause secular rates of the right ascension of the ascending node, whereas odd-degree zonal harmonics cause long-term periodic perturbations of the argument of perigee. The observations of changes in these Keplerian parameters can be used to derive Earth’s potential parameters. We investigate the relationship between the orbit perturbations as a function of the satellite height, inclination angle, and eccentricity to find optimum orbit parameters for the gravity field recovery which maximize the orbit perturbations. We employ the Kaula theorem of orbit perturbations based on the expansion of the gravity potential into trigonometric series and derive inclination F(i) and eccentricity functions G(e) for zonal even and odd-degree spherical harmonics. We also employ the satellite visibility function to find the optimum satellite height for the recovery of the global gravitational constant product GM, degree-1 spherical harmonics corresponding to the geocenter motion, Earth’s oblateness term C20, and other low-degree harmonics.
We found that the optimum heights of satellites for GM, geocenter, and degree-2 are in the areas where no geodetic satellites currently are; i.e., between 1700 and 3500 km. The best inclination angles for the even-degree harmonic recovery are in the range of 20-40 degrees for prograde or 140-160 degrees for retrograde orbits. The best separability of odd-degree harmonics is for critical inclinations (63.4, 116.6 deg) or high eccentricities. C30 can be well determined from a satellite at the inclination of 40 or 140 degrees at the height of 1400 km. To support future GRACE/MAGIC missions with C20 and C30, the best inclination would be about 40 or 140 degrees with a height of about 1500-1700 km. Finally, the best height for superior geocenter recovery and determination of the gravitational constant is about 2300 – 3500 km, which is in between the LAGEOS-1/2&LARES-2 height (5800 km) and LARES-1&Ajisai height (1500 km).
How to cite: Sośnica, K., Zajdel, R., Najder, J., Kur, T., and Gałdyn, F.: Determination of Earth’s gravity field parameters based on orbit perturbations – theoretical approach, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2581, https://doi.org/10.5194/egusphere-egu25-2581, 2025.
Marine gravity anomalies arise from the interaction between seafloor topography and the isostatic adjustment of the lithosphere. The admittance function quantifies the ability to transform seafloor topography into gravity anomalies. By developing various admittance function models, the connection between lithospheric response-induced gravity anomalies and seafloor topography is established, facilitating the inversion of seafloor topography from marine gravity anomalies. Addressing the various geophysical parameters involved in the admittance function approach, this study used the CRUST1.0 model as a priori data and proposed the Moving Windows Admittance Technique, adopting a 40 km moving step and 600 km × 600 km window to invert an effective elastic thickness model at a resolution of 5′×5′. The “remove-restore” technique was also incorporated to enhance accuracy. In the Mariana Trench region, the study revealed that the trench-arc-basin system exhibits anomalously low lithospheric strength (effective elastic thickness around 2 km), whereas the subducting plate demonstrates greater strength. The constructed seafloor topography model was verified with shipborne bathymetric data, demonstrating accuracy comparable to the DTU18 model and outperforming the SIO V23.1 model (about 36.5% improvement). These findings highlight that optimizing geophysical parameters significantly enhances the accuracy of seafloor topography inversion, providing critical insights for future oceanic research.
How to cite: Shen, R. and Zou, X.: Advances in Seafloor Topography Inversion: Integrating Admittance Functions and Geophysical Parameter Optimization, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2645, https://doi.org/10.5194/egusphere-egu25-2645, 2025.
Tidal forces represent a significant external influence on Earth's deformation and have been extensively studied, beginning with Lord Kelvin (W. Thomson, 1862), who first calculated the elastic deformation of a homogeneous, incompressible Earth under tidal forces. Later, Love (1911) extended this work by developing a formalism for a compressible, homogeneous, spherical, non-rotating elastic isotropic Earth (SNREI), introducing the concept of Love numbers to describe tidal effects through dimensionless parameters. The Earth's visco-elastic deformation due to tidal forces is typically modeled using Maxwell, and less frequently, Burgers rheologies in the mantle. In this work, we perform a comparative analysis of four major rheological models—Maxwell, Burgers, Andrade, and Sundberg-Cooper—to evaluate their efficacy in describing Earth's rheological behavior. While Andrade and Sundberg-Cooper models are rarely applied to Earth, they have demonstrated effectiveness in modeling the visco-elastic tidal response of planetary bodies and satellites. We have developed theoretical responses for each of these models from seismic frequencies to very long periods. We first compare the advanced Andrade (1910) and Sundberg-Cooper (2010) models with the more traditional Maxwell and Burgers models. We then focus on tidal responses by comparing predicted gravimetric factors for these models with those observed from long-term gravimetric data collected by superconducting gravimeters within the IGETS (International Geodynamics and Earth Tide Service) network and by SLR (Satellite Laser Ranging).
How to cite: saad, T., Rosat, S., and Boy, J.-P.: Earth’s Tidal Response for Maxwell, Burgers, Andrade and Sundberg-Cooper rheological models of the mantle , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2012, https://doi.org/10.5194/egusphere-egu25-2012, 2025.
The spectral combination method or technique encompasses all procedures to combine heterogeneous datasets by spectral weights, which depend on spherical harmonic degree n. This method was developed primarily to combine a global geopotential model (GGM) with terrestrial gravity data that is transformed into the gravity potential by integral formulas. Later, this method was extended to combine solutions to boundary-value problems (BVPs). The spectral combination method is based on the stochastic characteristics of measured gravity data, i.e., their signal and error degree-order variances. This technique represents the integral transform, in which the integral kernel is modified by spectral weights determined by the least-squares method.
So far, the spectral combination method has been applied only to solutions to spherical BVPs. In this contribution, we extend this method to solutions of vertical and horizontal spheroidal BVPs. Solutions of vertical and horizontal spheroidal BVPs for the gravitational potential have been presented by (Šprlák and Tangdamrongsub, 2018). Here, we derive corresponding solutions of vertical and horizontal spheroidal BVPs for first-, second- and third-order directional derivatives. Secondly, we derive the spectral weights for the corresponding solutions of vertical and horizontal spheroidal BVPs. Finally, we check the numerical correctness of the derived solutions of vertical and horizontal spheroidal BVPs and spectral weights in a closed-loop test with data from GGM.
How to cite: Pitonak, M., Belinger, J., Novak, P., and Sprlak, M.: Downward continuation of the gravitational gradient components to gravitational field quantities by spheroidal spectral combination technique, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4271, https://doi.org/10.5194/egusphere-egu25-4271, 2025.
Accelerometers have been widely used in almost every area of science and engineering. They are supposed to be physical instruments for measuring the acceleration of a moving object. Although huge technological advance is made in hardware of accelerometers over more than one century, accelerometers have been persistently designed and fabricated mechanically under the framework of forward problems of damped mass–spring systems. We show that accelerometers are essentially inverse ill-posed source problems from the mathematical point of view, implying that small measurement errors of equivalent displacements are inherently amplified significantly such that accelerations output from accelerometers can become extremely noisy, numerically incorrect and physically meaningless. The ill-posedness of accelerometers has been always implicitly circumvented approximately for more than one century. As a result, accelerometers theoretically can only produce approximate outputs of acceleration. Here we present the concept of computerized accelerometers, because inverse ill-posed problems, as in the case of accelerometers, cannot be rigorously solved mechanically. The acceleration can only rigorously be reconstructed computationally as a regularized solution to the inverse ill-posed source problem of acceleration from equivalent displacements. The concept of computerized accelerometers theoretically warrants precise measurement of acceleration without approximation, is valid for nonlinear time-dependent damping as well and provides a turning point for accelerometers to become a fully rigorous computerized physical instrument. Simulated examples have confirmed that least squares reconstruction of acceleration can be too extremely noisy to be physically meaningful and shown that elastic acceleration is incorrect by more than 100%.
How to cite: Xu, P.: Concept of computerized accelerometers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7936, https://doi.org/10.5194/egusphere-egu25-7936, 2025.
Recent advancements in geodesy have highlighted the dynamic interplay between theory, science, engineering, technology, and practice-oriented services. The continuous evolution of geodetic science has led to significant progress in both traditional geodetic challenges and emerging issues, often driven by innovations in instrumentation and computational techniques. This paper explores the potential to enhance airborne gravimetry by incorporating data from typically discarded flight segments—such as takeoff, landing, and turning periods—referred to as "preparing time" or "junk periods." While these phases are often excluded due to complexities in modeling aircraft accelerations, this study demonstrates the value of including this data in local gravity field modeling. Through simulations of gravity disturbances and rigorous downward continuation methods, we achieve significant improvements in precision (57%, 17%, and 12%) for data in the bandwidth from spherical harmonic degrees 200 to 1080. Notably, further improvements (55%, 41%, and 30%) are observed when extending the bandwidth from spherical harmonic degrees 1080 to 2160. This research emphasizes the importance of utilizing the entire flight trajectory to improve airborne gravimetry efficiency. The findings have implications for the integration of advanced technologies, such as quantum gravimeters with sub-mGal accuracy, as well as the coupling of various gravimetric systems, including vector gravimetry, to solve complex geodetic problems.
How to cite: Li, X.: Unlocked Potentials in Airborne Gravimetry, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11128, https://doi.org/10.5194/egusphere-egu25-11128, 2025.
In recent years, the number of space objects has been increasing rapidly. It has become crucial to utilize multi-source information fusion techniques for the orbit measurement and cataloguing of numerous objects. This report elaborates on the utilization of ground-based radar, optical, and space-based optical measurements in joint precision orbit determination. Regarding the real-time surveillance of a vast amount of space debris, investigations have been conducted concerning the initial orbit determination upon the first detection of targets, data association, orbit refinement, and the generation of catalogued orbital elements.Space-based technologies assume a particularly crucial role owing to their remarkable advantages in temporal and spatial coverage. To fulfill the data processing requisites for orbit determination of space-based measurement platforms, the onboard GNSS precision orbit determination software, SODA, has been developed, attaining centimeter-level accuracy in orbit determination. In the scenario of long-arc tracking via ground single-station astronomical optical cameras, an orbit determination accuracy within the range of several tens of meters can be accomplished. In the situation where multiple satellites are equipped with optical cameras, a substantial enhancement in the monitoring performance of space debris can be achieved both temporally and spatially.
How to cite: Yezhi, S.: Integrated Space-Based and Ground-Based Space Debris Orbit Determination, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4408, https://doi.org/10.5194/egusphere-egu25-4408, 2025.
Genesis is an ESA-approved mission dedicated to GNSS Science conducted by the ESA Navigation Directorate. Its primary objective is the contribution to the improvement of the International Terrestrial Reference Frame (ITRF) accuracy (1mm) and long-term stability (0.1mm/year). Secondary objectives include the contribution to a high number of other scientific disciplines (geodesy, geodynamics, earth rotation, geophysics, earth gravity field, atmosphere and ionosphere sciences, metrology, relativity…) [1].
The Genesis Space Segment includes a single spacecraft in MEO (6000km altitude, 95° inclination) co-locating for the first time in space the four geodetic instruments used for the realisation of ITRF: a GNSS receiver, an SLR reflector, a VLBI transmitter and a DORIS receiver. The Ground Segment is composed of a Mission Control Centre (including Ground Station) and will make use of the existing ground infrastructure, operated by the Scientific Community: GNSS sensor stations network, SLR stations, VLBI antennas and DORIS beacons. The scientific mission data will be processed, archived, and distributed by ESA’s Data PROcessing, Archiving and Delivery facility (PROAD), under the responsibility of the Navigation Support Office and the GNSS Science Support Centre, in close collaboration with the scientific community.
Genesis mission will implement a unique dynamic space geodetic observatory, allowing an extraordinary combination of innovative technology and fundamental science. As the ITRF is recognised to be the foundation for all space- and ground-based space mission activities, Genesis will have a major impact on almost any space missions and, in particular, on Navigation and Earth Science.
On the industrial side, the company OHB Italia has been contracted by ESA as prime for the development, qualification, launch and 2 years operation of the mission, with a launch date in 2028 [2]. Antwerp Space (B), as the major sub-contractor of OHB-I, oversees the payload and geodetic instruments. Industrial activities were kicked-off in April 2024, the System Requirements Review was successfully closed-out in Q4 2024, and work is on-going towards a Preliminary Design Review in Q4 2025.
In parallel, on the scientific side, after a successful Genesis Workshop held in February 2024 [3], a Genesis Science Team was set-up and members appointed. This structure includes representatives of ESA, a lead Scientific Coordinator and Co-Coordinator, as well as five Working Groups covering the four geodetic techniques and their combination. Genesis Science Team has been actively supporting the mission development (in particular consolidation of requirements) and will play a key role in its future exploitation.
The paper will provide a detailed description of the scientific objectives, mission, and system overview, and a programmatic status of the Genesis Mission.
[1]: Delva et al. Earth, Planets and Space 75, 5 (2023)
[2]: https://www.esa.int/Applications/Satellite_navigation/ESA_kicks_off_two_new_navigation_missions
[3]: https://www.esa.int/Applications/Satellite_navigation/The_geodetic_community_meets_Genesis
How to cite: Fusco, G., Gidlund, S., Waller, P., Morlet, C., Perez Lissi, F., Sakalauskaite, E., Enderle, W., Schoenemann, E., Berton, J.-C., Gini, F., and Navarro, V.: Genesis: A Unique Space Geodetic Observatory, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8240, https://doi.org/10.5194/egusphere-egu25-8240, 2025.
This study develops real-time continuous dynamic vertical reference for quantifying hydrodynamic processes with respect to high-resolution and accurate marine geoid model. In particular, this can now be realised through dynamic topography (DT), which is defined as the instantaneous sea surface height (SSH) deviation from the marine geoid (DT=SSH–geoid) and represents one of the most useful parameters of marine dynamics.
In regions of good quality and dense coverage of gravity data a 5 cm accurate marine geoid modelling is achievable. Due to the underlying accurate geoid model the DT values can now be estimated, eg. from a suitable hydrodynamic model, with the dm level accuracy. This corresponds to the most strict requirement for vertical accuracy at cargo handling in ports, dredging, maritime engineering, hydrography and under-keel clearance (UKC) management. This DT accuracy range also creates pre-conditions for identifying realistic sea level variations and circulation patterns of oceanic currents, seamlessly from the coastline toward the offshore over large basins.
Due to strict safety regulations various maritime and offshore applications require short term realistic sea level forecasts for hours to days in advance. Such near-real time DT estimations create a breakthrough opportunity for advancing from the “static” marine geoid referred vertical datum to the development of a new type vertical datum – a dynamic (both spatially and temporally) vertical reference frame. This continuous (and liquid!) DT field represents (either retrospectively or in the forecasting mode) the realistic sea level in absolute sense. Once DT is solved with sufficient accuracy then this dynamic DT field serves then as a reference (hence the name!) for developing further data products. These continuous DT field estimates are used for computing its spatio-temporal derivatives (eg. horizontal gradient), that might reveal ocean circulation patterns.
The Baltic Sea countries have been fortunate to have access to a wide range of marine data products, including that of a high-resolution marine geoid and hydrodynamic models that allow further capabilities to be explored in terms of sea level accuracy and validation. Accordingly, this study proposes a geodetic methodology that synergizes different sea level data sources by utilization of the marine geoid. The methodology applied utilized mathematical, statistical and machine learning strategies to obtain a spatio-temporally continuous dynamic topography of the Baltic Sea level. Sea level forecasting using DT is examined using machine learning approaches such as Convolution Neural Network. By using deep learning methods a DT modelling accuracy of within 10 cm has been achieved, which appears to better than the traditional data assimilation based forecasting.
Accomplishing this creates a marine dynamic vertical reference frame, which allows novel opportunities for marine digital twins, navigation, oceanographic processes and marine forecasting abilities.
How to cite: Ellmann, A., Delpeche-Ellmann, N., Varbla, S., Rajabi Kiasari, S., Jahanmard, V., and Kupavõh, A.: Development of continuous dynamic vertical reference for maritime and offshore engineering by applying geodetic and machine learning strategies, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20596, https://doi.org/10.5194/egusphere-egu25-20596, 2025.
Specific yield (Sy) is defined as the ratio of the volume of water that saturated rock or soil yields by gravity to the total volume of the rock or soil. Sy is often taken as a constant that when multiplied to groundwater level change provides water volume change, hence it is crucial in validating Gravity Recovery And Climate Experiment (GRACE)-derived groundwater changes, providing estimates of available groundwater resources, and in modelling groundwater aquifers. In this study, we used GRACE data and available quality-controlled in-situ well data to estimate Sy instead. Our hope was that it would match the available Sy, however we observed a time-varying Sy. Upon further investigation we found a negative correlation between water level and Sy. Hence the time-evolution of Sy was due to changes in the water level. We processed available well data and GRACE(-FO) in India, the United States, Europe, and Australia, spanning from January 2004 to December 2022. We also developed a general law/empirical relationship between Sy and groundwater level. All regional-specific empirical relationships exhibit a decrease in Sy as the average groundwater level depth drops, but the decay rate of Sy is notably faster in India (0.17 ± 0.04 m-1) compared to the United States (0.03 ± 0.01 m-1), Australia (0.06 ± 0.02 m-1), and European countries (0.04 ± 0.03 m-1). This empirical expression allows for the estimation of Sy based on readily available groundwater level data, thus supporting large-scale groundwater assessments and modelling efforts. At the global scale, a 50% decrease in Sy results in a groundwater level depletion of ~17 meters. However, in India, due to a faster decay rate, the same 50% reduction in Sy causes a groundwater level depletion of ~4 meters. This relationship can be utilized by hydrologists, water resource managers, and policymakers to predict Sy and assess changes in groundwater levels over time, aiding in more effective and sustainable water resource management.
How to cite: Kumar, K. S., Suryawanshi, M. R., Varadaganahalli Anandagowda, C., Shaw, B., Sukumaran, V., Kochar, A., and Vishwakarma, B. D.: GRACE satellites and in-situ well data reveals that specific yield declines with depleting groundwater levels, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-864, https://doi.org/10.5194/egusphere-egu25-864, 2025.
In this work we present a new method of determining the disturbing potential T and its functionals without using the Laplace equation.
The first step of this method is to solve two Dirichlet boundary value problems on the surface of the geoid related to a new partial differential equation (created by the author) named as G – modified Helmholtz equation. The solutions are formed after spherical approximation and describe gravity anomaly Δg and gravity disturbance δg as series of spherical harmonics.
In the second step we determine the disturbing potential T as a solution of a Dirichlet boundary value problem on the same boundary surface related to a very simple partial differential equation. Its Dirichlet boundary condition is formed with the aid of gravity anomaly, gravity disturbance and the fundamental boundary condition in spherical approximation. The solution is expressed as a series of spherical harmonics. As an epilogue to this work we present some new formulae for normal gravity γ, gravity g, vertical gradient of gravity, and mean curvature for actual equipotential surfaces as series of spherical harmonics.
The difference between known spherical harmonics and the introduced spherical harmonics is that the latter has the polar distance r in irrational powers. The advantage of this method is the simple determination of gravity anomaly, gravity disturbance and disturbing potential since it involves only Dirichlet boundary value problems. Finally this method shows that the determination of gravity anomaly and gravity disturbance can be made without determining the disturbing potential.
How to cite: Manoussakis, G.: Determination of the Earth’s disturbing potential and its functionals as series of spherical harmonics, without using the Laplace equation. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2088, https://doi.org/10.5194/egusphere-egu25-2088, 2025.
The Gravity Recovery and Climate Experiment (GRACE) mission has revolutionized our understanding of Earth’s mass redistribution. However, enhancing the utility of GRACE products remains challenging due to inherent trade-offs between the temporal and spatial resolution, constrained by the mission design. High autocorrelation at the first lag in geoid coefficient time series is a key feature that enables the development of improved forecasting frameworks. Building on this temporal persistence of gravity coefficients, we propose a predictive framework to characterize the relationship between monthly and finer temporal scale-uncertainties of geoid coefficients. The proposed method enables reducing the finer temporal scale-uncertainties to levels comparable with known monthly uncertainties within the ranges of higher spectral degrees. With reduced uncertainties of finer temporal scales for higher spherical harmonic degrees, this predictive framework sets the groundwork for enhancing the analyses of rapid mass variations in the context of regional hydrology.
How to cite: Kankanige, D., Vishwakarma, B., Liu, Y., and Sharma, A.: A forecasting framework for enhancing gravity variations of finer temporal scales., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-280, https://doi.org/10.5194/egusphere-egu25-280, 2025.
Knowledge of the potential difference (altitude above sea level Hγ) or spatial position (ellipsoidal height H) at the measurement point leads to two main types of free-air gravity reduction: anomalies Δg and disturbances δg.
This gives rise to geodetic boundary problems of determining the external anomalous potential T or its transformants (on the Earth's boundary surface S and beyond it), which are solved, in particular, using a family of functions orthogonal on a geometrically regular surface maximally close to the boundary surface (a sphere Ω or an oblate ellipsoid); in a more general case, the apparatus of integral equations should be used (for example, with respect to the density of a simple layer φ, which explains the external anomalous field).
When the anomalous potential is found from the solution of one boundary value problem, it is possible to transform it to a gravity reduction corresponding to another boundary value problem.
In modern conditions, a situation is theoretically and practically possible when both the normal Hγ and geodetic H heights are known, thus, the anomalous potential T itself at a point on the Earth's surface is considered known, the accuracy of its calculation in a linear measure is limited by the accuracy of knowledge of the heights (the first centimeters).
Further, calculations of the elements of the anomalous field can be formally performed based on the solution of the first boundary value problem, but an increase in the order of the derivative of the anomalous potential leads to a loss of accuracy during the next differentiation.
Therefore, as initial data, it is better to have such a derivative whose order is as close as possible to the desired value, so that the relevance of gravity measurements does not decrease.
As a result of such measurements complex, it is possible to calculate separately the Δg and δg.
It is generally believed that calculations using δg lead to a more accurate result due to the known boundary surface (although using the potential difference instead of the spatial position is more justified from a physical point of view).
But which type of gravity reduction would be optimal?
Solution of the geodetic boundary value problem for determining the anomalous potential T at an external point P has a very simple form in the spherical approximation if we introduce a special gravity reduction Πg with the corresponding boundary condition on the Earth's surface S:
The integration kernel 2/r is convenient because it does not contain the natural logarithm.
It is of interest to derive a more accurate boundary condition taking into account Earth's flattening.
Also, in spherical approximation, one can obtain an integral equation (*), which is significantly simpler than the integral equations (**) and (***):
The simplicity of such a gravity reduction was first noted by L.P.Pellinen and O.M.Ostach in their article on some topographic gravity anomalies. See: Stud Geophys Geod 18, 319–328 (1974), https://doi.org/10.1007/BF01627186
How to cite: Popadyev, V. and Alena, D.: Optimal gravity reduction when anomalous potential is known, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6301, https://doi.org/10.5194/egusphere-egu25-6301, 2025.
Modeling the gravitational effects of the topography and other layers of the Earth’s interior is one of the fundamental topics in geodesy and geophysics. Previous formulas of the Gravitational Potential (GP), Gravitational Vector (GV), and Gravitational Gradient Tensor (GGT) of a vertical cylindrical prism were derived from complex conversion relations and were relatively complicated. In this contribution, we derive the optimized formulas through a particular geometrical relation between the computation point and integration point, which are consistent with the previous expressions. The analytical formulas of the GP, GV, and GGT of a cylindrical shell are presented when the computation point is located on the polar axis. Based on these formulas, a cylindrical shell benchmark is put forward to evaluate the numerical properties of the cylindrical prism, that is, to discretize a whole cylindrical shell into cylindrical prisms. Beyond the improved simplicity, our optimized formulas with a second-order 3D Taylor series expansion help to save computation time (particularly for the GGT up to 20%). Numerical results reveal that when the computation point's vertical distance changes, the relative and absolute errors are symmetric with respect to the center vertical distance of the cylindrical shell. Accompanying codes in Python for a vertical cylindrical prism and a cylindrical shell are provided at https://www.github.com/xiaoledeng/optimized-formulas-of-gp-gv-ggt.
How to cite: Deng, X.-L., Sneeuw, N., and Tsoulis, D.: Optimized formulas of the gravitational field of a vertical cylindrical prism, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5583, https://doi.org/10.5194/egusphere-egu25-5583, 2025.
The gravity field of a level oblate spheroid is formulated in this study using various coordinate systems. From the viewpoint of physical characteristics, it is assumed that this ellipsoid of revolution encloses mass, rotates with constant angular velocity and is a level (or equipotential) surface of its own gravity field. First, a spheroidal coordinate system and spheroidal harmonics are introduced. An exterior Dirichlet boundary-value problem is solved to determine the gravitational potential. As a result, the gravity potential is calculated completely and uniquely outside of the ellipsoid. Its closed form is then given in Cartesian, spherical, and geodetic coordinates. The gravity vector is calculated from the gravity potential in the exterior space and on the surface of the level ellipsoid. Additionally, the classical theorems of Clairaut, Pizzetti, and Somigliana are presented. Second, because the Earth's ellipsoid deviates slightly from a sphere, series expansions in terms of eccentricities for the normal gravity field are provided. Finally, the field is expanded in terms of spherical harmonics, which are useful for interpretations and calculations.
How to cite: Panou, G. and Marti, U.: New formulation for the normal gravity field, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5919, https://doi.org/10.5194/egusphere-egu25-5919, 2025.
The structure of the Laplace operator is relatively simple when expressed in terms of spherical or ellipsoidal coordinates. The physical surface of the Earth, however, substantially differs from a sphere or an oblate ellipsoid of revolution, even if optimally fitted. The same holds true for the solution domain and the exterior of a sphere or of an oblate ellipsoid of revolution. The situation is more convenient in a system of general curvilinear coordinates such that the physical surface of the Earth (smoothed to a certain degree) is imbedded in the family of coordinate surfaces. Therefore, a transformation of coordinates is applied in treating the geodetic boundary value problem. The transformation contains also an attenuation function. Subsequently, tensor calculus is used and the Laplace operator is expressed in the new coordinates. Its structure becomes more complicated now. Nevertheless, in a sense it represents the topography of the physical surface of the Earth. For this reason the Green’s function method is used together with the method of successive approximations in the solution of the geodetic boundary value problem expressed in terms of the new coordinates. The structure of iteration steps is analyzed and if possible, it is modified by means of integration by parts. The iteration steps and their convergence are discussed and interpreted. The approach is also compared with the method of analytical continuation.
How to cite: Holota, P.: Divergence of the gradient, solution domain geometry and successive approximations in gravity field studies, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12189, https://doi.org/10.5194/egusphere-egu25-12189, 2025.
To establish the gravity database for the African geoid, it is needed to remove the blunders from the available gravity data set. As the available gravity data for Africa is very limited, including large data gaps, the gross errors detection technique should be smart enough to eliminate only the real blunders. A smart gross error detection technique has been adopted. It is based on the least squares prediction algorithm. The technique works first to estimate the gravity value at the data station using other values than the current data point. It thus compares the estimated value to the data value for possible blunder detection. Hence the technique measures the influence of removing the data value of a current point on the neighbourhood stations. Only if the value of a certain station proves to be blunder, it is then removed from the data base. Another effective technique to estimate the blunder in the gravity database of Africa is designed using the Artificial Intelligence. The results of both gross errors detection techniques are compared and analyzed in order to give a proper judge on both algorithms.
How to cite: Abd-Elmotaal, H. and Kühtreiber, N.: Gross Errors Detection for the African Gravity Database, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6382, https://doi.org/10.5194/egusphere-egu25-6382, 2025.
New devices often come along with new data structures and formats, and new instrument technologies require a new method of data processing. In recent years, BKG and GFZ have operated novel absolute quantum gravimeters (AQG) by Exail (formerly Muquans) in different environments for geodetic and hydrological applications. Here we present a newly released open-source library “gravitools” [1] we have developed for the handling and post-processing of AQG raw data.
The library is designed as a toolbox of data structures for common data handling, but also routines for standardized processing. For this new instrument there is yet no agreed upon standard method for these two aspects. With gravitools, we aim at providing a solid approach to address this topic and actively contribute to the necessary development of such a standard within the gravimetry community. In order to enhance usability, gravitools was developed as a user-friendly, reliable software application both for non-experts and advanced users. To this end, it offers a command-line, scripting and graphical user interface, which provides advanced users the option to precisely define their individual settings and routines. This contribution will provide an overview of implemented key features and their usage (data handling, processing, visualizing, documenting and archiving) as well as an outlook of planned extensions, such as the integration of similar features for CG-6 gravimeters.
The gravitools library It is written purely in Python and released on the Python Package Index (PyPI). It is licensed as open-source to make it freely available to the scientific community and encourage feedback and contributions.
[1] gravitools: https://gitlab.opencode.de/bkg/gravitools
How to cite: Reich, M., Glässel, J., Wziontek, H., and Güntner, A.: gravitools: an open-source toolbox in Python for post-processing Exail Absolute Quantum Gravimeter (AQG) and other terrestrial gravimeter data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11169, https://doi.org/10.5194/egusphere-egu25-11169, 2025.
The least-squares method is commonly utilized to address data processing problems. The "adjustment in steps" technique is used in this study to optimize the "adjustment of measurements only" method. We use an initial set of condition equations of a mathematical model, to compute the initial best estimates of a given set of measurements. Subsequently, we may add or remove conditions from either the same model or a new form of it. The final solution is produced by revising the initial estimations of the measurements without applying the adjustment procedure to the entire system of condition equations. This technique is generalized in several steps. Each stage involves revising measurement estimates. The splitting of the solution system into steps simplifies the adjustment procedure because each step includes the multiplication and inversion of smaller matrices than those used for the complete system. Furthermore, the efficiency of this technique as a function of the number of steps taken is examined. The smallest amount of computations required to handle a large number of measurements yields the best solution. Finally, nonlinear condition equations are investigated. Numerical experiments are used to validate the theoretical concepts.
How to cite: Koci, J. and Panou, G.: Adjustment of a large number of measurements in steps, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4725, https://doi.org/10.5194/egusphere-egu25-4725, 2025.
In our research, we propose a novel numerical approach based on the finite element method applied for modelling time variations of global Earth’s gravity field in the space domain. As input data we use the GRACE-FO satellite gravity data which are prolonged and filtered on the Earth's surface, while the Earth's surface is determined by digital elevation model on lands and mean sea surface obtained by satellite altimetry. Then the surface gravity disturbances on the Earth's surface serve as the boundary condition for the geodetic boundary value problem. Away from the Earth we involve the so-called mapped infinite elements which naturally prescribe the regularity of the disturbing potential at infinity. Afterwards, the obtained solution is determined at every moment when new input data is applied. In this way, we dynamically determine the Earth's gravity field on and above the Earth's topography.
How to cite: Minarechová, Z., Macák, M., Korekáčová, B., and Čunderlík, R.: Modelling time variations of global gravity field by the finite element method, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4804, https://doi.org/10.5194/egusphere-egu25-4804, 2025.
Thanks to existing algorithms for Legendre functions, it is fairly possible to perform spherical harmonic transforms up to degrees as high as a few tens of thousands. In fact, many algorithms are often accurate even well beyond this point. From the practical point of view, however, hardware-related challenges emerge when the truncation degree exceeds, say, 100,000. For instance, to conduct a degree-100,000 spherical harmonic transform, be it forward or backward, it is necessary to store in memory about 75 GBs of spherical harmonic coefficients and about 149 GBs of the signal to be analyzed/synthesized at the Gauss--Legendre grid (with Driscoll--Healy grids, the signal-related memory even doubles). Although systems with that amount of shared memory are not rare, the point becomes clear when further extending harmonic degree to, say, 150,000 (168 GB + 335 GB) or beyond. With such extensive transforms, one has to sooner or later move to systems with distributed memory.
This contribution discusses the implementation of spherical harmonic transforms on distributed-memory systems in CHarm, which is a C/Python library for high-degree spherical harmonic transforms. To this end, CHarm employs the Message Passing Interface (MPI), allowing to distribute both the coefficients and the signal among a number of independent shared-memory systems that can communicate together. These could be, for instance, nodes of high-performance computing clusters or a few ordinary PCs interconnected via some network protocol (e.g., SSH). Since the computation of a signal at any point requires all spherical harmonic coefficients and vice versa, the amount of data transferred is immense. We show how this challenge is tackled in CHarm. Furthermore, we discuss how CHarm combines the MPI parallelization (between shared-memory systems), the OpenMP parallelization (within shared-memory systems) and the SIMD parallelization (within a single CPU core), all at the same time. As a toy example, some spherical harmonic transforms up to degree 100,000 and beyond are shown.
In Physical Geodesy, high-degree spherical harmonic transforms are useful, for instance, to model planetary topographies. More specifically, spherical harmonic degree 100,000 offers 200-meter spatial resolution on the Earth's surface. Systems with distributed memory thus make it feasible for spherical harmonics to capture fine details of the Earth's and other planetary topographies. As another use case, it is known that topography truncated at some finite non-zero harmonic degree generates gravitational field possessing an infinite number of spherical harmonics. Therefore, to accurately describe the gravitation field of, say, a degree-10,800 Earth's topography, the truncation degree of the implied potential series should generally be extended from 10,800 to degree as high as possible, say, 108,000 or so.
CHarm is free software available from https://github.com/blazej-bucha/charm. The documentation with cookbook-style examples can be found at https://www.charmlib.org.
This study was funded by the EU NextGenerationEU through the Recovery and Resilience Plan for Slovakia under the project No. 09I03-03-V04-00273.
How to cite: Bucha, B.: Spherical harmonic transforms up to degree 100,000 and beyond using distributed-memory systems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-67, https://doi.org/10.5194/egusphere-egu25-67, 2025.
The poster discusses the solution of the Poisson equation for the gravitational potential of irregularly shaped bodies by the finite element method (FEM) in ANSYS software. The aim of this research is to study whether the FEM can overcome the limitations of the spherical-harmonic-based approaches, namely their divergence in the vicinity of the gravitating body. The objects of investigation are three asteroids: 433 Eros, 25143 Itokawa and 101955 Bennu. The computational domain is a sphere with a radius 10 times larger than the average radius of the selected asteroid, at the origin of which the given asteroid is located. The input to the computation is the density of the asteroids, while outside the asteroid zero density is considered. The output is the gravitational potential and gravitational acceleration in the vicinity of the asteroids. The results of the computations are compared with the solutions by the spherical and spheroidal harmonic-based approaches.
How to cite: Macák, M. and Minarechová, Z.: Application of the finite element method to the modelling of the gravitational field of asteroids, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4830, https://doi.org/10.5194/egusphere-egu25-4830, 2025.
The standard theoretical framework for the gravitational field determination often relies on spherical approximation. However, Earth’s shape is much closer to a rotational ellipsoid flattened at the poles, as proved by the legendary expeditions of the French Academy of Sciences to South America and Lapland already in the 18th century. Contemporary investigations of solar system planetary bodies have revealed that many resemble prolate or oblate ellipsoids, whereas a high amount of them is flattened more significantly than the Earth. Four such spheroidal bodies have recently been subject to immense research interest: 1) Mars being explored by satellite and lander missions as it represents a potential target for future colonisation, 2) the asteroid Bennu explored by the sample-return satellite mission OSIRIS-REx, 3) the dwarf planet Ceres, and 4) the asteroid Vesta, both explored by the satellite mission Dawn. Moreover, several comets and asteroids with spheroidal (ellipsoidal) shapes have been subjected to intense small-body research. Consequently, there is an urgent need to formulate a modern theoretical framework for the gravitational field determination.
In this contribution, we formulate a mathematical theory for modelling of gravitational fields generated by ellipsoidal bodies. In addition, we present both theory and software considering non-singular solution for derived equations using recurrences instead of classical approach, which depends on reduced spheroidal latitude. Using recurrences, we can eliminate singularities on poles and computational errors in their proximity caused by latitude dependence.
How to cite: Belinger, J., Dohnalova, V., Pitonak, M., Novak, P., and Sprlak, M.: Global gravitational field modelling for spheroidal planetary bodies: non-singular solutions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10368, https://doi.org/10.5194/egusphere-egu25-10368, 2025.
We present 3D numerical modelling of the altimetry-derived marine gravity data with the high horizontal resolution 1 x 1 arc min. The finite volume method (FVM) as a numerical method is used to solve the altimetry-gravimetry boundary-value problem. Large-scale parallel computations result in disturbing potential in every finite volume of the discretized 3D computational domain between an ellipsoidal approximation of the Earth’s surface and upper boundary chosen at altitude of 200 km. Afterwards, the first, second or third derivatives of the disturbing potential in different directions are numerically derived using the finite differences. A process of preparing the Dirichlet boundary conditions over ocean/seas has a crucial impact on achieved accuracy. It is based on nonlinear filtering of the geopotential generated on a mean sea surface (MSS) from a GRACE/GOCE-based satellite-only global geopotential model.
We present different types of the altimetry-derived marine gravity data obtained on the DTU21_MSS as well as at higher altitudes of the 3D computational domain. The altimetry-derived gravity disturbances on the DTU21_MSS are tested by shipborne gravimetry and compared with those from the recent datasets like DTU21_GRAV or SS_v31.1. The obtained altimetry-derived gravity disturbances at higher altitudes are compared with airborne gravity data from the GRAV-D campaign in US. The gravity disturbing gradients as the second derivates or the third derivatives are provided with the same high resolution on the DTU21_MSS as well as at different altitudes.
How to cite: Čunderlík, R., Macák, M., Kollár, M., Minarechová, Z., and Mikula, K.: 3D high-resolution numerical modelling of altimetry-derived marine gravity data using FEM, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5601, https://doi.org/10.5194/egusphere-egu25-5601, 2025.
In regions with complex terrain, terrain correction is essential for accurately computing geoid undulations. The accuracy of Digital Terrain Models (DTMs), which include both terrestrial and marine datasets, has a significant impact on terrain correction and geoid modeling. One striking example is the coastal region of Hualien in eastern Taiwan, located at the land-sea boundary. This area is renowned for its dramatic topographical shifts, where elevations plummet from over 2000 meters above sea level to ocean depths exceeding 2000 meters within just a few kilometers. This study evaluates the effects of various global and regional Digital Elevation Models (DEMs) and Digital Bathymetric Models (DBMs) on geoid modeling in Hualien. The geoid modeling strategy utilizes a remove-restore approach, combining global geopotential models, local gravity observations, and high-resolution DEMs and DBMs. Particular attention is given to the accuracy of these DEMs and DBMs at the critical land-sea interface, where topographic variations are most pronounced. To validate the results, we compare them against high-resolution satellite imagery and the Global Self-consistent, Hierarchical, High-resolution Geography Database (GSHHG) coastline data. Additionally, geoid models derived from different DEM-DBM combinations are assessed using high-precision GNSS-leveling geometric geoid observations at multiple locations within the study area. The primary aim of this research is to improve terrain correction accuracy in areas with complex topography along land-sea boundaries, ultimately enhancing the precision and reliability of geoid modeling results.
How to cite: Yang, Z. Y., Fang, K.-H., and Hsiao, Y.-S.: Assessing the Influence of DEM and DBM Accuracy on Geoid Modeling at the Land-Sea Interface: A Case Study in Eastern Taiwan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2128, https://doi.org/10.5194/egusphere-egu25-2128, 2025.
We use data from the GRAIL and LRO satellite missions to estimate the horizontally varying density of the lunar crust. We determine the density model by parametrising the density using spherical harmonic functions up to degree 400. The density estimate depends on the difference between the data from the global gravitational field model generated by the topography measured by the LOLA sensor and the data from the GL1500E global gravitational field model derived from the GRAIL mission. To reduce the numerical complexity of the calculations, we approximate the topography by a sphere and test the sensitivity of the density estimates to the size of the spherical radius. We further calculate a global gravitational field model generated by the estimated horizontally varying density and the LOLA topography. We analyse the results by admittance, correlation, and Bouguer fields for degrees 150-600. The highest agreement with the input data is obtained for the approximating sphere identical to its Brillouin counterpart. Overall, the horizontally varying density model provides a more realistic gravitational field than the one from the constant crustal density. The advantages of the applied approach lie in the speed of calculation, low requirements on hardware, and ease of implementation.
How to cite: Šprlák, M. and Perkner, V.: Lunar crustal density estimate from the GRAIL and LOLA-based global gravitational field models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2861, https://doi.org/10.5194/egusphere-egu25-2861, 2025.
Taiwan’s terrain is predominantly mountainous, with approximately 73% of its total land area classified as sloped terrain. The region is characterized by complex geological conditions, short yet steep and fast-flowing rivers, and a high susceptibility to natural disasters. During the summer and autumn seasons, typhoons and heavy rainfall frequently trigger landslides in mountainous areas, posing significant risks to infrastructure and communities. While numerous studies have investigated landslide susceptibility in this region, few have examined the impact of different geoid models on these analyses. In Taiwan, geoid models are periodically updated, and these changes can influence key analytical factors in landslide susceptibility assessments, potentially affecting the outcomes. This study utilizes high-resolution digital elevation models (DEMs) based on various global geoid models, such as EGM96 and EGM2008, as well as regional geoid models like TWGEOID2014, TWGEOID2023, and TWGEOID2024, to assess their influence on landslide susceptibility. This study focuses on the mountainous areas of central Taiwan, which also exhibit the largest differences in geoid models. Logistic regression analysis is performed using IBM SPSS statistics software, incorporating terrain factors such as aspect, slope, curvature, relief, and roughness to evaluate landslide susceptibility. Landslide susceptibility maps and receiver operating characteristic (ROC) curves are generated for each geoid model and compared to assess their differences. The findings of this research aim to improve the precision of disaster prediction and provide valuable insights for disaster prevention efforts, soil and water conservation, and integrated risk management strategies. Additionally, this study highlights the importance of geoid model selection in geospatial analyses and its broader implications for environmental and engineering applications.
How to cite: Fang, K. H., Yang, Z. Y., and Hsiao, Y. S.: Evaluating the Impact of Geoid Model Variations on Landslide Susceptibility: A Case Study in Taiwan's Mountainous Regions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1820, https://doi.org/10.5194/egusphere-egu25-1820, 2025.
Geothermal energy is a significant source of clean, renewable energy, and the Bavarian Molasse Basin demonstrates exceptional potential for its development. Over the past two decades, the region has made remarkable progress in harnessing geothermal energy. Between 1998 and 2021, a total of 30 deep geothermal energy projects were implemented in Bavaria, with 24 systems currently in operation. Munich is a leader among European cities in utilizing centralized geothermal systems, with plans to fully cover the city’s energy needs through geothermal resources by 2040.
However, the operation of geothermal power plants can induce seismic activity and alter the stress-strain state of the subsurface, posing potential threats to the environment and population. Induced seismicity is a key issue for geothermal projects worldwide, where its occurrence has caused significant delays in development and, in some cases, damage to buildings and infrastructure.
To evaluate the impact of geothermal activity on surface deformation, we processed a dense network of Sentinel-1 interferograms (2018-2021) using Small Baseline Subset (SBAS) InSAR time-series analysis through NASA's Alaska Satellite Facility (ASF) OpenSARLab. This approach enabled us to generate high-precision cumulative displacement and velocity maps across Munich and its surrounding areas over the three-year period.
Our analysis revealed localized ground uplift throughout the region, with pronounced deformation rates near certain geothermal plants, in some cases reaching a few cm/year. These uplift patterns appear to correlate with geothermal operations, particularly reservoir pressure changes and fluid reinjection. In contrast, areas of subsidence, observed away from geothermal sites, appear to result from natural geological processes such as sediment compaction, groundwater extraction, and karstification.
These findings are vital for seismic hazard assessments, as surface deformation is closely tied to induced seismicity in geothermal environments. The study underscores the importance of advanced geodetic monitoring techniques, such as InSAR, for evaluating seismic risks and ensuring the sustainable development of geothermal energy resources.
How to cite: Semenova, Y., Seitz, M., Bloßfeld, M., and Seitz, F.: Geodetic monitoring of surface deformation for mitigating induced seismicity in Bavarian geothermal operations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4198, https://doi.org/10.5194/egusphere-egu25-4198, 2025.
Seafloor topography prediction plays a crucial role in filling data gaps in regions lacking ship sounding measurements. However, the reliance of prediction algorithms on ship sounding data varies significantly. This study evaluates the impact of ship sounding coverage and distribution on the prediction accuracy of two methods: the gravity–geologic method (GGM) and an analytical algorithm. Simulation experiments reveal that increasing the ship sounding coverage from 5.40% to 31.80% and achieving a more uniform distribution significantly enhance the accuracy of the GGM, reducing the RMS error from 238.68 m to 42.90 m (an improvement of 82.03%). In contrast, the analytical algorithm maintains a stable RMS error of 40.39 m, demonstrating independence from ship sounding data. Further analysis in a 1° × 1° sea area (134.8°–135.8°E, 30.0°–31.0°N) shows that higher ship sounding coverage (33.19%) reduces the GGM RMS error from 204.17 m to 126.95 m compared to lower coverage (8.19%). However, the analytical algorithm's RMS error remains consistent at 167.94 m. These results underscore the GGM's sensitivity to ship sounding data and the analytical algorithm's robustness. The findings highlight the importance of combining algorithms based on ship sounding coverage. For regions where coverage exceeds 30%, the GGM offers superior accuracy. Conversely, the analytical algorithm performs better in low-coverage scenarios. This study provides a basis for integrating multiple algorithms to enhance global seafloor topography models.
How to cite: Tian, Y., Yu, J., and Xu, H.: Comparison of Seafloor Topography Prediction Using the Gravity-Geologic Method and Analytical Algorithm, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8273, https://doi.org/10.5194/egusphere-egu25-8273, 2025.
Accurate monitoring of sea level variations is crucial for understanding climate change impacts and supporting coastal management. However, traditional methods like tide gauges and satellite altimetry face limitations in coverage and precision. This research explores the capabilities of GNSS/IMU buoy systems for enhancing sea surface height measurements and depth datum assessments. By deploying GNSS/IMU buoys near 34 tide gauge stations across Taiwan, a comparative analysis was conducted to examine the reliability and precision of these innovative tools against conventional tide gauge data. Utilizing advanced loosely coupled GNSS/IMU integration of GNSS and IMU data, the study achieves centimeter-level accuracy in dynamic marine conditions. Results reveal that while most tide gauges are consistent with the buoy data, significant discrepancies are observed at a few stations, particularly in subsidence areas and offshore islands. This study underscores the potential of GNSS/IMU buoy systems as a cost-effective and flexible solution to complement tide gauges, especially in regions affected by vertical land motion. The findings advocate for broader adoption of GNSS/IMU technologies to improve coastal and offshore hydrographic observations under changing environmental conditions.
How to cite: Kuo, C.-Y., Lan, W.-H., Lee, C.-M., Kao, H.-C., and Tseng, T.-P.: Enhancing Sea Surface Height Monitoring and Depth Datum Assessment Using GNSS/IMU Buoy Systems: A Case Study of Taiwan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7740, https://doi.org/10.5194/egusphere-egu25-7740, 2025.
Since April 2024 the Conrad observatory, located 60 km SW of Vienna within a karstic area of the Eastern Alps (Austria), operates a superconducting iGrav gravimeter (iGrav050) continuing the previous more than 10 years long gravity time series of GWR C025. Their gravity residuals indicated an extremely complex local hydrology in the surroundings of the observatory. For better understanding the local hydrological processes a geoelectric profile has been installed which monitors a 2D resistivity section each day. The profile runs across the topography just above the gravimeter. The latter is an underground installation. The situation is challenging because the profile runs closely above cavities built up by the observatory’s underground labs and tunnel. In addition, the geoelectric settings are limited by the requirements of the nearby geomagnetic observatory.
In September 2024 an extraordinary rain event happened in Lower Austria with cumulative rain as large as 400 mm within a few days. First results are shown comparing the gravity signal with the time dependent resistivity sections providing insight to the water content within the terrain top layer. In addition, the gravity residual signals are compared to those originating from a snowmelt event in 2009 with similarly large water intrusion during short time as in September 2024.
How to cite: Arneitz, P., Meurers, B., Jochum, B., Ita, A., Ottowitz, D., Leonhardt, R., and Egli, R.: Gravity and 2D time lapse resistivity monitoring at Conrad Observatory for understanding local hydrology – case study of an exceptional rain event in September 2024, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15367, https://doi.org/10.5194/egusphere-egu25-15367, 2025.
