Integrating NGS GRAV-D gravity observations into high-resolution global models

2021 ◽  
Author(s):  
Philipp Zingerle ◽  
Xiaopeng Li ◽  
Martin Willberg ◽  
Roland Pail ◽  
Dan Roman
Keyword(s):  
High Resolution ◽  
Gravity Data ◽  
Equation System ◽  
Normal Equation ◽  
Global Models ◽  
Gravity Field Model ◽  
Computational Performance ◽  
Global Gravity ◽  
Actual Observation ◽  
Collocation Approach

<p>Within this contribution we present a method that allows a smooth integration of in-situ ground gravity observations into high-resolution global models up to d/o 5400 (2’ global resolution). The functionality is shown on the example of the airborne GRAV-D gravity dataset which is integrated into a global satellite-topographic spherical harmonic model.</p><p>Conceptually, the method is divided into three steps: firstly, since the processing is based on residuals, a precursor model needs to be identified which is used for reducing the observations. In the actual example a combination between a satellite-only model (GOCO06s) and topographic model (EARTH2014) is chosen (named SATOP2) to ensure independency to the observations. Secondly, the previously reduced (GRAV-D) observations are gridded onto a regular geographic grid making use of the recently developed partition-enhanced least squares collocation approach (PE-LSC). PE-LSC allows an efficient collocation of virtually arbitrary large datasets using a partitioning technique that is optimized for computational performance and for minimizing fringe effects. As a third and last step, the obtained regular grid gets analyzed and combined with a satellite-only model (GOCO06s) on the normal equation level up to d/o 5400. This can be achieved efficiently by using a so-called kite-normal equation system which emerges when combining dense and block-diagonal normal equation systems (assuming equal accuracies for the ground gravity grid).</p><p>The herby obtained global gravity field model, named SGDT, is dominated by the satellite information in the lower frequencies (up to d/o 200), by GRAV-D in the mid-frequencies (d/o 200-2000) and by the topographic information in the high frequencies (above d/o 2000). The main purpose of the SGDT model is to validate the method itself and to allow a comparison of GRAV-D observations to pre-existing ground-gravity data by synthesizing SGDT to actual observation sites.</p>

High-resolution combined global gravity field modelling – The d/o 5,400 XGM2020 model

2020 ◽  
Author(s):  
Philipp Zingerle ◽  
Roland Pail ◽  
Thomas Gruber
Keyword(s):  
High Resolution ◽  
Gravity Field ◽  
Gravity Anomalies ◽  
Normal Equation ◽  
Terrestrial Gravity ◽  
Gravity Field Modelling ◽  
Field Modelling ◽  
Global Gravity ◽  
Very High ◽  
Block Diagonal

<p>Within this contribution we present the new experimental combined global gravity field model XGM2020. Key feature of this model is the rigorous combination of the latest GOCO06s satellite-only model with global terrestrial gravity anomalies on normal equation level, up to d/o 2159, using individual observation weights. To provide a maximum resolution, the model is further extended to d/o 5400 by applying block diagonal techniques.</p><p>To attain the high resolution, the incorporated terrestrial dataset is composed of three different data sources: Over land 15´ gravity anomalies (by courtesy of NGA) are augmented with topographic information, and over the oceans gravity anomalies derived from altimetry are used.  Corresponding normal equations are computed from these data sets either as full or as block diagonal systems.</p><p>Special emphasis is given to the novel processing techniques needed for very high-resolution gravity field modelling. As such the spheroidal harmonics play a central role, as well as the stable calculation of associated Legendre polynomials up to very high d/o. Also, a new technique for the optimal low-pass filtering of terrestrial gravity datasets is presented.</p><p>On the computational side, solving dense normal equation systems up to d/o 2159 means dealing with matrices of the size of about 158TB. Handling with matrices of such a size is very demanding, even for today’s largest supercomputers. Thus, sophisticated parallelized algorithms with focus on load balancing are crucial for a successful and efficient calculation.</p>

scholarly journals Signal and error assessment of GOCE-based high resolution gravity field models

2019 ◽  
Vol 9 (1) ◽  
pp. 71-86 ◽  
Author(s):  
T. Gruber ◽  
M. Willberg
Keyword(s):  
High Resolution ◽  
Gravity Field ◽  
Gravity Data ◽  
Geoid Height ◽  
Harmonic Series ◽  
Regional Data ◽  
Data Set ◽  
Global Models ◽  
The Impact ◽  
Gravity Field Models

Abstract The signal content and error level of recent GOCE-based high resolution gravity field models is assessed by means of signal degree variances and comparisons to independent GNSS-levelling geoid heights. The signal of the spherical harmonic series of these models is compared to the pre-GOCE EGM2008 model in order to identify the impact of GOCE data, of improved surface and altimetric gravity data and of modelling approaches. Results of the signal analysis show that in a global average roughly 80% of the differences are due to the inclusion of GOCE satellite information, while the remaining 20% are contributed by improved surface data. Comparisons of the global models to GNSS-levelling derived geoid heights demonstrate that a 1 cm geoid from the global model is feasible, if there is a high quality terrestrial gravity data set available. For areas with less good coverage an accuracy of several centimetres to a decimetre is feasible taking into account that GOCE provides now the geoid with a centimetre accuracy at spatial scales of 80 to 100 km. Comparisons with GNSS-levelling geoid heights also are a good tool to investigate possible systematic errors in the global models, in the spirit levelling and in the GNSS height observations. By means of geoid height differences and geoid slope differences one can draw conclusions for each regional data set separately. These conclusions need to be considered for a refined analysis e.g. to eliminate suspicious GNSS-levelling data, to improve the global modelling by using full variance-covariance matrices and by consistently weighting the various data sources used for high resolution gravity field models. The paper describes the applied procedures, shows results for these geoid height and geoid slope differences for some regional data sets and draws conclusions about possible error sources and future work to be done in this context.

scholarly journals Validation of GOCE global gravity field models using terrestrial gravity data in Norway

2012 ◽  
Vol 2 (2) ◽  
pp. 134-143 ◽  
Author(s):  
M. Šprlák ◽  
C. Gerlach ◽  
B. Pettersen
Keyword(s):  
Harmonic Analysis ◽  
Gravity Field ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Gravity Field Model ◽  
Terrestrial Gravity ◽  
Free Air ◽  
Global Gravity ◽  
Free Air Gravity ◽  
Gravity Field Models

Validation of GOCE global gravity field models using terrestrial gravity data in NorwayThe GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite gravity gradiometry mission maps the Earth's gravity field. Harmonic analysis of GOCE observations provides a global gravity field model (GGFM). Three theoretical strategies, namely the direct, the space-wise and the time-wise approach, have been proposed for GOCE harmonic analysis. Based on these three methods, several GGFMs have been provided to the user community by ESA. Thereby different releases are derived from different periods of GOCE observations and some of the models are based on combinations with other sources of gravity field information. Due to the multitude of GOCE GGFMs, validation against independent data is a crucial task for the quality description of the different models.In this study, GOCE GGFMs from three releases are validated with respect to terrestrial free-air gravity anomalies in Norway. The spectral enhancement method is applied to avoid spectral inconsistency between the terrestrial and the GOCE free-air gravity anomalies.The results indicate that the time-wise approach is a reliable harmonic analysis procedure in all three releases of GOCE models. The space-wise approach, available in two releases, provides similar results as the time-wise approach. The direct approach seems to be highly affected by a-priori information.

scholarly journals P-wave velocity and density structure beneath Mt. Vesuvius: a magma body in the upper edifice?

2013 ◽  
Vol 56 (4) ◽  
Author(s):  
Paolo Capuano ◽  
Guido Russo ◽  
Roberto Scarpa
Keyword(s):  
High Resolution ◽  
Wave Velocity ◽  
Gravity Data ◽  
High Energy ◽  
P Wave ◽  
Gravity Inversion ◽  
Density Structure ◽  
Resolution Image ◽  
High Resolution Image ◽  
P Wave Velocity

<p>A high-resolution image of the compressional wave velocity and density structure in the shallow edifice of Mount Vesuvius has been derived from simultaneous inversion of travel times and hypocentral parameters of local earthquakes and from gravity inversion. The robustness of the tomography solution has been improved by adding to the earthquake data a set of land based shots, used for constraining the travel time residuals. The results give a high resolution image of the P-wave velocity structure with details down to 300-500 m. The relocated local seismicity appears to extend down to 5 km depth below the central crater, distributed into two clusters, and separated by an anomalously high Vp region positioned at around 1 km depth. A zone with high Vp/Vs ratio in the upper layers is interpreted as produced by the presence of intense fluid circulation alternatively to the interpretation in terms of a small magma chamber inferred by petrologic studies. In this shallower zone the seismicity has the minimum energy, whilst most of the high-energy quakes (up to Magnitude 3.6) occur in the cluster located at greater depth. The seismicity appears to be located along almost vertical cracks, delimited by a high velocity body located along past intrusive body, corresponding to remnants of Mt. Somma. In this framework a gravity data inversion has been performed to study the shallower part of the volcano. Gravity data have been inverted using a method suitable for the application to scattered data in presence of relevant topography based on a discretization of the investigated medium performed by establishing an approximation of the topography by a triangular mesh. The tomography results, the retrieved density distribution, and the pattern of relocated seismicity exclude the presence of significant shallow magma reservoirs close to the central conduit. These should be located at depth higher than that of the base of the hypocenter volume, as evidenced by previous studies.</p>

scholarly journals AUTOMATIC MRF-BASED REGISTRATION OF HIGH RESOLUTION SATELLITE VIDEO DATA

2016 ◽  
Vol III-1 ◽  
pp. 121-128 ◽  
Author(s):  
C. Platias ◽  
M. Vakalopoulou ◽  
K. Karantzalos
Keyword(s):  
High Resolution ◽  
Markov Random Fields ◽  
Video Data ◽  
Registration Accuracy ◽  
Registration Method ◽  
Computational Performance ◽  
Markov Random ◽  
Video Frames ◽  
Reference Map ◽  
The Cost

In this paper we propose a deformable registration framework for high resolution satellite video data able to automatically and accurately co-register satellite video frames and/or register them to a reference map/image. The proposed approach performs non-rigid registration, formulates a Markov Random Fields (MRF) model, while efficient linear programming is employed for reaching the lowest potential of the cost function. The developed approach has been applied and validated on satellite video sequences from Skybox Imaging and compared with a rigid, descriptor-based registration method. Regarding the computational performance, both the MRF-based and the descriptor-based methods were quite efficient, with the first one converging in some minutes and the second in some seconds. Regarding the registration accuracy the proposed MRF-based method significantly outperformed the descriptor-based one in all the performing experiments.

scholarly journals High Resolution Ancestry Deconvolution for Next Generation Genomic Data

2021 ◽  
Author(s):  
Helgi Hilmarsson ◽  
Arvind S. Kumar ◽  
Richa Rastogi ◽  
Carlos D. Bustamante ◽  
Daniel Mas Montserrat ◽  
...  
Keyword(s):  
High Resolution ◽  
Prediction Models ◽  
Association Studies ◽  
Training Data ◽  
Genome Wide Association Studies ◽  
Whole Genome ◽  
Next Generation ◽  
Genome Data ◽  
Computational Performance ◽  
Genetic Risk Prediction

ABSTRACTAs genome-wide association studies and genetic risk prediction models are extended to globally diverse and admixed cohorts, ancestry deconvolution has become an increasingly important tool. Also known as local ancestry inference (LAI), this technique identifies the ancestry of each region of an individual’s genome, thus permitting downstream analyses to account for genetic effects that vary between ancestries. Since existing LAI methods were developed before the rise of massive, whole genome biobanks, they are computationally burdened by these large next generation datasets. Current LAI algorithms also fail to harness the potential of whole genome sequences, falling well short of the accuracy that such high variant densities can enable. Here we introduce Gnomix, a set of algorithms that address each of these points, achieving higher accuracy and swifter computational performance than any existing LAI method, while also enabling portable models that are particularly useful when training data are not shareable due to privacy or other restrictions. We demonstrate Gnomix (and its swift phase correction counterpart Gnofix) on worldwide whole-genome data from both humans and canids and utilize its high resolution accuracy to identify the location of ancient New World haplotypes in the Xoloitzcuintle, dating back over 100 generations. Code is available at https://github.com/AI-sandbox/gnomix.

Joint receiver function and gravity inversion for new constraints on the Ivrea body structure: a 2D high-resolution view along the Val Sesia profile (N. Italy).

2021 ◽  
Author(s):  
Matteo Scarponi ◽  
György Hetényi ◽  
Jaroslava Plomerová ◽  
Stefano Solarino
Keyword(s):  
High Resolution ◽  
Velocity Structure ◽  
Receiver Function ◽  
Joint Inversion ◽  
Gravity Data ◽  
Rock Physics ◽  
Receiver Functions ◽  
Gravity Inversion ◽  
European Alps ◽  
Horizontal Distance

&lt;p&gt;We present results from a joint inversion study of new seismic and gravity data to constrain a 2D high-resolution image of one of the most prominent geophysical anomalies of the European Alps: the Ivrea geophysical body (IGB). Our work exploits both new data and multidisciplinary a priori constraints, to better resolve the shallow crustal structure in the Ivrea-Verbano zone (IVZ), where the IGB is known to reach anomalously shallow depths and partially outcrop at the surface.&lt;/p&gt;&lt;p&gt;A variety of previous studies, ranging from gravity surveys to vintage refraction seismics and recent local earthquake tomographies (Solarino et al. 2018, Diehl et al. 2009), provide comprehensive but spatially sparse information on the IGB structure, which we aim at investigating at higher resolution, along a linear profile crossing the IVZ. To this purpose, we deployed 10 broadband seismic stations (MOBNET pool, IG CAS Prague), 5 km spaced along a linear West-East profile, along Val Sesia and crossing Lago Maggiore. This network operated for 27 months and allowed us to produce a new database of ca. 1000 seismic high-quality receiver functions (RFs). In addition, we collected new gravity data in the IVZ, with a data coverage of 1 gravity point every 1-2 km along the seismic profile. The newly collected data was used to set up an inversion scheme, in which RFs and gravity anomalies are jointly used to constrain the shape and the physical property contrasts across the IGB interface.&lt;/p&gt;&lt;p&gt;We model the IGB as a single interface between far-field constraints, whose geometry is defined by the coordinates of four nodes which may vary in space, and &amp;#160;density and V&lt;sub&gt;S&lt;/sub&gt; shear-wave velocity contrasts associated with the interface itself, varying independently. A Markov chain Monte Carlo (MCMC) sampling method with Metropolis-Hastings selection rule was implemented to efficiently explore the model space, directing the search towards better fitting areas.&lt;/p&gt;&lt;p&gt;For each model, we perform ray-tracing and RFs migration using the actual velocity structure both for migration and computation of synthetic RFs, to be compared with the observations via cross-correlation of the migration images. Similarly, forward gravity modelling for a 2D density distribution is implemented and the synthetic gravity anomaly is compared with the observations along the profile. The joint inversion performance is the product of these two misfits.&lt;/p&gt;&lt;p&gt;The inversion results show that the IGB reaches the shallowest depths in the western part of the profile, preferentially locating the IGB interface between 3 and 7 km depth over a horizontal distance of ca. 20 km (between Boccioleto and Civiasco, longitudes 8.1 and 8.3). Within this segment, the shallowest point reaches up to 1 km below sea level. The found density and velocity contrasts are in agreement with rock physics properties of various units observed in the field and characterized in earlier studies.&lt;/p&gt;

Evaluation of High-Resolution Atmospheric Transport Modelling within the framework of the CTBT with Xe-133 observations in Germany and stack emission data from medical isotope production

2021 ◽  
Author(s):  
Jolanta Kusmierczyk-Michulec ◽  
Anne Tipka ◽  
Martin Kalinowski
Keyword(s):  
High Resolution ◽  
Atmospheric Transport ◽  
International Monitoring System ◽  
Isotope Production ◽  
Emission Data ◽  
Transport Modelling ◽  
Atmospheric Transport Modelling ◽  
Computational Performance ◽  
International Monitoring ◽  
Medical Isotope

&lt;p&gt;For every atmospheric radionuclide sample taken by the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty&amp;#160;Organisation&amp;#160;(CTBTO), the CTBTO makes use of operational Atmospheric Transport Modelling (ATM) to assist States Signatories in localization of possible source regions of any measured substance. Currently, ATM is accomplished by using the&amp;#160;Lagrangian&amp;#160;particle dispersion model (LPDM) FLEXPART driven by global meteorological fields with a spatial resolution of 0.5 degrees and 1 hourly temporal resolution. Meteorological fields are provided by the&amp;#160;European Centre for Medium-Range Weather&amp;#160;Forecasts (ECMWF )&amp;#160;and the&amp;#160;National Centers for Environmental Prediction (NCEP).&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;Recent studies to increase the accuracy in the&amp;#160;CTBTO&amp;#8217;s localization&amp;#160;process to be applied for specific detection events, utilizes High-Resolution Atmospheric Transport Modelling (HRATM) by using the&amp;#160;Weather Research and Forecasting model (WRF) to generate high-resolution meteorological input data for the LPDM version&amp;#160;Flexpart-WRF.&amp;#160;&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;This presentation uses measurements from the International Monitoring System (IMS) station DEX33 in Germany of seven episodes of elevated Xe-133 concentrations in 2014 in combination with&amp;#160;with&amp;#160;the stack emission data of the medical isotope production facility&amp;#160;IRE in&amp;#160;Fleurus, Belgium. Each episode consists of 6 to 11 subsequent 24-hour samples. Backward simulations for each sample are conducted and the sensitivity to the stack emission data are&amp;#160;analysed. All samples determined to represent a detection of IRE releases are selected to be used for an evaluation study.&amp;#160;&lt;/p&gt;&lt;p&gt;Evaluating the CTBTO&amp;#8217;s utilization of HRATM requires to investigate the ability to localize the source region as well as the accuracy of the match and the computational performance to accomplish these results. The evaluation of HRATM results is done by using statistical metrics established during former ATM challenges. Concerning the computational performance and to account for uncertainties, sensitivity studies with varying spatial resolutions, physical parameterization variations and different regional domain setups for WRF were accomplished. This&amp;#160;comprises a&amp;#160;reference comparison to the operational ATM FLEXPART model with an increased spatial resolution to 0.1 degrees.&amp;#160;&amp;#160;&amp;#160;&lt;/p&gt;

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