A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  

              [Sort by number of followers]   [Restore default list]

  Subjects -> METEOROLOGY (Total: 113 journals)
Showing 1 - 36 of 36 Journals sorted alphabetically
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 4)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 45)
Advances in Climate Change Research     Open Access   (Followers: 39)
Advances in Meteorology     Open Access   (Followers: 28)
Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 10)
Aeolian Research     Hybrid Journal   (Followers: 6)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 20)
American Journal of Climate Change     Open Access   (Followers: 34)
Atmósfera     Open Access   (Followers: 3)
Atmosphere     Open Access   (Followers: 29)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 16)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 13)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 48)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 16)
Atmospheric Environment     Hybrid Journal   (Followers: 75)
Atmospheric Environment : X     Open Access   (Followers: 3)
Atmospheric Research     Hybrid Journal   (Followers: 71)
Atmospheric Science Letters     Open Access   (Followers: 40)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 32)
Bulletin of Atmospheric Science and Technology     Hybrid Journal   (Followers: 5)
Bulletin of the American Meteorological Society     Open Access   (Followers: 51)
Carbon Balance and Management     Open Access   (Followers: 5)
Ciencia, Ambiente y Clima     Open Access   (Followers: 3)
Climate     Open Access   (Followers: 6)
Climate and Energy     Full-text available via subscription   (Followers: 7)
Climate Change Economics     Hybrid Journal   (Followers: 33)
Climate Change Responses     Open Access   (Followers: 18)
Climate Dynamics     Hybrid Journal   (Followers: 44)
Climate of the Past (CP)     Open Access   (Followers: 5)
Climate of the Past Discussions (CPD)     Open Access  
Climate Policy     Hybrid Journal   (Followers: 51)
Climate Research     Hybrid Journal   (Followers: 6)
Climate Resilience and Sustainability     Open Access   (Followers: 21)
Climate Risk Management     Open Access   (Followers: 7)
Climate Services     Open Access   (Followers: 3)
Climatic Change     Open Access   (Followers: 68)
Current Climate Change Reports     Hybrid Journal   (Followers: 10)
Developments in Atmospheric Science     Full-text available via subscription   (Followers: 31)
Dynamics and Statistics of the Climate System     Open Access   (Followers: 5)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 19)
Earth Perspectives - Transdisciplinarity Enabled     Open Access  
Economics of Disasters and Climate Change     Hybrid Journal   (Followers: 9)
Energy & Environment     Hybrid Journal   (Followers: 24)
Environmental and Climate Technologies     Open Access   (Followers: 4)
Environmental Dynamics and Global Climate Change     Open Access   (Followers: 17)
Frontiers in Climate     Open Access   (Followers: 3)
GeoHazards     Open Access   (Followers: 2)
Global Meteorology     Open Access   (Followers: 18)
International Journal of Atmospheric Sciences     Open Access   (Followers: 23)
International Journal of Biometeorology     Hybrid Journal   (Followers: 1)
International Journal of Climate Change Strategies and Management     Hybrid Journal   (Followers: 27)
International Journal of Climatology     Hybrid Journal   (Followers: 30)
International Journal of Environment and Climate Change     Open Access   (Followers: 12)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 2)
Journal of Agricultural Meteorology     Open Access  
Journal of Applied Meteorology and Climatology     Hybrid Journal   (Followers: 36)
Journal of Atmospheric and Oceanic Technology     Hybrid Journal   (Followers: 34)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 210)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 22)
Journal of Climate     Hybrid Journal   (Followers: 57)
Journal of Climate Change     Full-text available via subscription   (Followers: 16)
Journal of Climatology     Open Access   (Followers: 3)
Journal of Hydrology and Meteorology     Open Access   (Followers: 36)
Journal of Hydrometeorology     Hybrid Journal   (Followers: 11)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Journal of Meteorological Research     Full-text available via subscription   (Followers: 1)
Journal of Meteorology and Climate Science     Full-text available via subscription   (Followers: 17)
Journal of Space Weather and Space Climate     Open Access   (Followers: 28)
Journal of the Atmospheric Sciences     Hybrid Journal   (Followers: 84)
Journal of the Meteorological Society of Japan     Partially Free   (Followers: 6)
Journal of Weather Modification     Full-text available via subscription   (Followers: 2)
Large Marine Ecosystems     Full-text available via subscription   (Followers: 1)
Mediterranean Marine Science     Open Access   (Followers: 1)
Meteorologica     Open Access   (Followers: 2)
Meteorological Applications     Hybrid Journal   (Followers: 4)
Meteorological Monographs     Hybrid Journal   (Followers: 2)
Meteorologische Zeitschrift     Full-text available via subscription   (Followers: 3)
Meteorology and Atmospheric Physics     Hybrid Journal   (Followers: 27)
Mètode Science Studies Journal : Annual Review     Open Access  
Michigan Journal of Sustainability     Open Access   (Followers: 1)
Modeling Earth Systems and Environment     Hybrid Journal   (Followers: 1)
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 16)
Monthly Weather Review     Hybrid Journal   (Followers: 33)
Nature Climate Change     Full-text available via subscription   (Followers: 144)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 39)
Nīvār     Open Access  
npj Climate and Atmospheric Science     Open Access   (Followers: 6)
Open Atmospheric Science Journal     Open Access   (Followers: 4)
Open Journal of Modern Hydrology     Open Access   (Followers: 7)
Revista Brasileira de Meteorologia     Open Access  
Revista Iberoamericana de Bioeconomía y Cambio Climático     Open Access  
Russian Meteorology and Hydrology     Hybrid Journal   (Followers: 3)
Space Weather     Full-text available via subscription   (Followers: 25)
Studia Geophysica et Geodaetica     Hybrid Journal  
Tellus A     Open Access   (Followers: 22)
Tellus B     Open Access   (Followers: 21)
The Cryosphere (TC)     Open Access   (Followers: 6)
The Quarterly Journal of the Royal Meteorological Society     Hybrid Journal   (Followers: 28)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 13)
Tropical Cyclone Research and Review     Open Access  
Urban Climate     Hybrid Journal   (Followers: 4)
Weather     Hybrid Journal   (Followers: 18)
Weather and Climate Dynamics     Open Access  
Weather and Climate Extremes     Open Access   (Followers: 16)
Weather and Forecasting     Hybrid Journal   (Followers: 27)
Weatherwise     Hybrid Journal   (Followers: 4)
气候与环境研究     Full-text available via subscription   (Followers: 1)

              [Sort by number of followers]   [Restore default list]

Similar Journals
Journal Cover
Studia Geophysica et Geodaetica
Journal Prestige (SJR): 0.38
Citation Impact (citeScore): 1
Number of Followers: 0  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1573-1626 - ISSN (Online) 0039-3169
Published by Springer-Verlag Homepage  [2658 journals]
  • Error bounds for the spectral approximation of the potential of a
           homogeneous almost spherical body

    • Free pre-print version: Loading...

      Abstract: Several kinds of approximation of the gravitational potential of a homogeneous body by truncated spherical harmonics series are in use in physical geodesy. However, only one of them is capable of a representation converging to the true potential in the whole layer between the Brillouin sphere and the Bjerhammar sphere of the body. We aim at providing various majorizations, namely upper bounds, of the error with the double purpose of proving explicitly the convergence in the sense of different norms and of giving computable bounds, that might be used in numerical studies. The first aim is reached for all the norms. For the second, however, it turns out that among the bounds, when applied to the example of the terrain correction of the Earth, only those referring to the mean absolute error and the mean squared error at the level of Brillouin sphere of minimum radius give significant and useful results. In order to make the computation an easy exercise, a simple approximate formula has been developed requiring only the use of the distribution function of the heights of the surface of the body with respect to the Bjerhammar sphere.
      PubDate: 2021-09-04
       
  • The stability criterion for downward continuation of surface gravity data
           with various spatial resolutions over Ireland

    • Free pre-print version: Loading...

      Abstract: The differences between local and reference geopotential values are the fundamental quantities of interest in the geodetic boundary value problem approach for connecting independent height reference frames. The local gravity potential values are usually derived from gravimetric and geometric geoid undulations. In determining the short-wavelength components of the gravimetric geoid, a harmonic or analytical downward continuation of the external harmonic functions of gravity to the geoid is necessary. This study analyses the stability of the Poisson downward continuation technique with respect to varying the spatial resolution of surface gravity data in Ireland in order to estimate an effective grid resolution on this reduction. Results of the study show that the minimum range of 500-m resolution provides an unconditionally stable solution to downward continuation without the need for regularisation of the computation algorithm. In this case, downward continued data contribute from −13 to 12 mm to geoid heights and from −0.128 to 0.118 m2s−2 to local gravity potential value at Malin-Head tide gauge station in Ireland.
      PubDate: 2021-09-04
       
  • Erratum to “Bounds and averages of seismic quality factor Q”

    • Free pre-print version: Loading...

      PubDate: 2021-07-28
       
  • Relationship between soil magnetic susceptibility enhancement and
           precipitation in Cretaceous paleosols

    • Free pre-print version: Loading...

      Abstract: Magnetic susceptibility (MS) is widely used for paleoclimate reconstruction. In one of the previous studies, data from 12 locations of modern middle- and low-latitude soils revealed that MS increases with increasing precipitation from approximately 200 to 1000–1200 mm yr−1 and then decreases with further precipitation. However, as a result of diverse sediment sources from different locations, the MS value can deviate, affecting its relationship with the climate. Sediments of a section experience dry-wet contrast due to the migration of climate zones as a function of geological time, and form different soil types with various colors. If the sediments of a section have the same source material, different soil types in that section would enable us to explore the relationship between MS enhancement and precipitation using paleosols and to verify the previous results. Herein, we investigated Cretaceous variegated sediments in the Zhonggou and Xiagou Formations located in the Hexi Corridor of China. The rare earth and trace element analyses reveal that these sediments have the same source area. Environmental magnetism and geochemical methods reveal that the sedimentary environment of the yellowish-brown, red, and grayish-white sediments ranges from dry to wet. Precipitation reconstruction for the paleosols with a climate transfer function shows that MS increases with increasing precipitation up to approximately 800 ± 182 mm yr−1 and decreases with higher precipitation amounts. The changing pattern of MS is consistent with the previous results, but the inflection point in the MS vs. precipitation curve appears at slightly lower precipitation value. Thus, paleosol sequences are suited for the analysis of paleoprecipitation trends with the help of MS.
      PubDate: 2021-07-28
       
  • Velocity structure of the upper crust beneath the Jiaonan uplift and its
           adjacent areas, China

    • Free pre-print version: Loading...

      Abstract: The Jiaonan uplift and its adjacent areas (JUAA) are the result of collision and amalgamation of the North China plate and Yangtze plate. In this area, the tectonic environment is complex and crustal deformation is strong. However, detailed and in-depth study of the upper crustal structure and medium properties in the JUAA has not previously been performed. The high-resolution three-dimensional crustal velocity structure of the JUAA is helpful to analyze the characteristics of the crustal structure in this area and is important for evaluating the tectonic environment and medium properties of the JUAA. We obtained the three-dimensional crustal velocity structure in the JUAA using the double-difference seismic tomography technique, and found that the Rizhao area and the sea areas to its southwest in the Jiaonan uplift are characterized by a high-velocity structure, and that most of the high-velocity anomaly area is located in the sea area. The crustal velocity values of the southern end of the Yishu fault zone are also high. The high crustal velocity anomaly areas in the JUAA are considered to be caused by the upwelling of mantle material. The velocity structure of the upper crust beneath the depression structures shows notable low-velocity anomalies, which are closely related to loose sediments in the depression structures. The existence of abnormally high-velocity and low-velocity structures in the Jiaonan uplift indicates that there are substantial differences in the properties of the crustal media in the Jiaonan uplift. Crust-mantle interaction in the Jiaonan uplift is mainly concentrated in the Rizhao area and sea areas to its southwest.
      PubDate: 2021-04-01
       
  • Assessment of state of earth dam of Elchovka settling pond by combination
           of electromagnetic soundings and polarization methods

    • Free pre-print version: Loading...

      Abstract: Earth dams are constantly under the hydraulic pressure. Their long-term operation leads to arising of zones of increased water cut and filtration in body and base of dams. This weakens dam’s strength. Geophysical methods can be used to control condition of the soil structures. We describe the research results of the Elchovka earth dam by a complex of electrometric methods, as they are most sensitive to changes in soil moisture. We applied the self-potential (SP) method, the vertical electrical soundings (VES) and the remote induction soundings (RIS) with the study of the frequency dispersion of electrical resistivity. Main pathways of the water filtration were identified by the self-potential method. According to the results of RIS, the boundary between bulk and natural soils as well as the boundary between sedimentary and bedrock are clearly distinguished. Electric soundings on direct current (VES) allowed us to localize places with reduced resistivities due to increased soil moisture. Frequency dispersion anomalies, which can also indicate water filtration in bulk soils and bedrock, were found. On the investigated dam, anomalies of the electrical conductivity and the frequency dispersion coincide with anomalies of the self-potential. This indicates increased filtration. Thus, the use of the remote induction soundings and the frequency dispersion methods together with widely applied VES and SP methods enhances the reliability of research and provides additional information about the hydrogeological situation in the area of the dam.
      PubDate: 2021-04-01
       
  • Alternative formulae for robust Weighted Total Least-Squares solutions for
           Errors-In-Variables models

    • Free pre-print version: Loading...

      Abstract: Weighted Total Least-Squares (WTLS) can optimally solve the issue of parameter estimation in the Errors-In-Variables (EIV) model; however, this method is relatively sensitive to outliers that may exist in the observation vector and/or the coefficient matrix. Hence, an attempt to identify/suppress those outliers is in progress and will ultimately lead to a novel robust estimation procedure similar to the one used in the Gauss-Markov model. The method can be considered as a follow-up to the WTLS solution formulated with the standard Least-Squares framework. We utilize the standardized total residuals to construct the equivalent weights, and apply the median method to obtain a robust estimator of the variance to provide good robustness in the observation and structure spaces. Moreover, a preliminary analysis for the robustness of related estimators within the EIV model is conducted, which shows that the redescending M-estimates are more robust than the monotonic ones. Finally, the efficacy of the proposed algorithm is demonstrated through two applications, i.e. 2D affine transformation and linear regression on simulated data and on real data with some assumptions. Unfortunately, the proposed algorithm may not be reliable for detecting multiple outliers. Therefore, MM-estimates within the EIV model need to be investigated in further research.
      PubDate: 2021-04-01
       
  • Comparison of three methods for computing the gravitational attraction of
           tesseroids at satellite altitude

    • Free pre-print version: Loading...

      Abstract: Global gravity modelling is one of the most important issues in geophysics and geodesy. Because a tesseroid model comprises the curvature of the Earth, the computation methods for the gravitational potential of tesseroids and its first-order derivatives in spherical coordinates are attracting great attention in recent years. In this paper we deal with the numerical evaluation of the radial component of the gravitational attraction generated by tesseroid masses at satellite height with the Gauss-Legendre quadrature (GLQ), the Taylor series expansion (TSE) and the prism approximation (PA) methods. Forward modelling of tesseroids of 1° × 1° and 5′ × 5′ are performed by three computation methods and the comparison between them are made in terms of computational efficiency and accuracy. The numerical results show that the GLQ of order 5 can provide the adequate accuracy for the gravity modelling of 1° × 1° tesseroids at satellite height. The GLQ of order 2 and TSE methods are superior to the PA approach in both computational accuracy and efficiency. The satellite height has important impact on the accuracy of the GLQ and TSE, whereas it has no effect on the PA method. In addition, we developed combined GLQ approach and combined TSE method, respectively, for global gravity modelling based on 1° × 1° and 5′ × 5′ tesseroids. Apart from the synthetic tesseroids, 1° × 1° data from the CRUST1.0 global crustal model and 5′ × 5′ rock-equivalent topographic data from the Earth2014 model are used to validate two combined methods. The numerical results show that these two combined methods can balance the computational accuracy and efficiency.
      PubDate: 2021-04-01
       
  • An alternative geoid model for Africa using the shallow-layer method

    • Free pre-print version: Loading...

      Abstract: The aim of the current investigation is to determine an alternative geoid model for Africa using the shallow-layer method. The shallow-layer method, following the basic definition of the geoid, differs essentially from the traditional geoid determination techniques (Stokes and Molodensky) that it doesn’t need real gravity data. It comes from the definition of the geoid. Here, the shallow-layer method is used to determine a 5′ × 5′ geoid model for Africa covering the latitudes between −36°N and 39°N and longitudes from −20°E to 53°E The Earth Gravitational Model (EGM2008), the global topographic model (DTM2006.0), the global crustal model (CRUST1.0) and the Danish National Space Center data set (DNSC08) global models have been used to construct and define the shallow layer and its interior structure. A combination of prism and tesseroid modelling methods have been utilized to determine the gravitational potential produced by the shallow-layer masses. The validation and tests of the computed shallow-layer geoid have been done at two different levels. First, a comparison between the computed shallow-layer geoid and the recently developed AFRgeo2019 gravimetric geoid for Africa (based on real gravity data) has been carried out. Second, a comparison of the computed shallow-layer geoid with several geoid models computed using different global geopotential models has been performed. The results show that the computed shallow-layer geoid behaves similarly to those determined by the global geopotential models. Differences between the shallow-layer and the AFRgeo2019 gravimetric geoids are generally small (below 0.5 m) at most of the African continent
      PubDate: 2021-04-01
       
  • Two-dimensional magnetotelluric data inversion using Lanczos
           bidiagonalization method with active constraint balancing

    • Free pre-print version: Loading...

      Abstract: The magnetotelluric (MT) technique is an electromagnetic geophysical method, which is widely used as a complementary to seismic surveys for exploration of hydrocarbon reservoirs. In the inversion process, the method of matrix inverse calculation has a considerable effect on the speed of the inversion and the quality of obtained models. Lanczos Bidiagonalization (LB) method has been reported to be a fast and efficient approach for solving the inversion problems. In this study, we employ LB method for inverting large-scale 2D MT data. In LB algorithm, the full set of equations is replaced by a dimensionally reduced system of equations. As a result, the speed of the solution procedure is increased, while the original problem is solved with a high accuracy. In addition, we employ active constraint balancing approach for determining the optimum regularization parameter. The advantage of the method is that for highly resolvable parameters, a small value of the Lagrangian multiplier is assigned, and vice versa. The results of the synthetic data inversion show that both methods require equal computer memory but LB method is faster and more reliable than conjugate gradient method. The proposed approach is also applied to inverse real MT data collected from the Kashan area. The Kashan area is the most interesting area for oil and gas exploration of the Central Iran Basin. The inversion results obtained by LB are in a good agreement with the geological structure of the study area and the drilling data.
      PubDate: 2021-04-01
       
  • Representation theorem for viscoelastic waves with a non-symmetric
           stiffness matrix

    • Free pre-print version: Loading...

      Abstract: In an elastic medium, it was proved that the stiffness tensor is symmetric with respect to the exchange of the first pair of indices and the second pair of indices, but the proof does not apply to a viscoelastic medium. In this paper, we thus derive the representation theorem for viscoelastic waves in a medium with a non-symmetric stiffness matrix. The representation theorem expresses the wave field at a receiver, situated inside a subset of the definition volume of the viscoelastodynamic equation, in terms of the volume integral over the subset and the surface integral over the boundary of the subset. For the given medium, we define the complementary medium corresponding to the transposed stiffness matrix. We define the frequency-domain complementary Green function as the frequency-domain Green function in the complementary medium. We then derive the provisional representation theorem as the relation between the frequency-domain wave field in the given medium and the frequency-domain complementary Green function. This provisional representation theorem yields the reciprocity relation between the frequency-domain Green function and the frequency-domain complementary Green function. The final version of the representation theorem is then obtained by inserting the reciprocity relation into the provisional representation theorem.
      PubDate: 2021-01-01
       
  • Vertical distribution of magnetic susceptibility as affected by
           pedoenvironmental factors along an arid and semi-arid transect, Fars
           Province, Iran

    • Free pre-print version: Loading...

      Abstract: Soil magnetism provides valuable information about soil-landscape relationships and soil evolution. However, only limited number of studies on the relationship between soil magnetic properties and soil forming factors and processes, especially in arid and semi-arid regions, are available. The aim of this study was to determine vertical distribution of soil magnetic susceptibility and selected pedoenvironmental parameters and to interpret them in terms of the soil evolution. Eight representative soil profiles were selected on different geomorphic surfaces including alluvial fan, piedmont plain and flood plain. Soil samples were collected from different diagnostic horizons and analyzed for routine physico-chemical properties, different iron forms and magnetic susceptibility. The average values of magnetic susceptibility (χlf) and relative frequency-dependent magnetic susceptibility in the studied soils are 53.1 × 10−8 m3 kg−1 and 2.62%, respectively, with the latter ranging from 0 to 6.88%. The negative significant correlation (with correlation coefficient R = −0.48 and statistical significance p < 0.01) between soil evolution index (ratio of acid oxalate soluble and free Fe oxides — Feo/Fed) and χlf values indicated that χlf increased with soil evolution. A positive significant correlation between χlf and Fed (and Fed — Feo) values, and a negative significant correlation between χlf and CaCO3 values were observed. The vertical distribution of χlf along the studied profiles showed different patterns (uniform, non-uniform, ascending and descending) with depth. Overall, the results indicated that the χlf distribution along the soil profiles was affected by topography, distribution of different iron forms, soil evolution, and weathering rate in different soil layers.
      PubDate: 2021-01-01
       
  • Recent Macaronesian kinematics from GNSS ground displacement analysis

    • Free pre-print version: Loading...

      Abstract: Macaronesia is a complex oceanic region spanning three tectonic plates in the northeast Atlantic ocean. It is composed of four archipelagos, widely distributed and limited to the east by the Iberian Peninsula and north-western coast of Africa. This study aims to clarify recent Macaronesian kinematics from 19 GNSS stations located on the four archipelagos and the Iberian and African coastlines. The analysis is based on nearly 15 years of common data acquisition and aimed to detect new effects of intraplate tectonics or similar local/regional events consistent with calculated ground displacements. Evaluating the GNSS stations residual velocities relative to those expected from the NNR-MORVEL56 model, higher residuals were found at continental coastal stations (Africa) than at oceanic ones (Canaries and Madeira). From the computed strain rate map, the possible existence of a shear zone connecting the Gloria and Transmoroccan fault systems, already mentioned by other authors, was depicted. Cluster statistical analysis of the horizontal residual velocities helped to identify tectonic boundaries in Macaronesia and four groups of analogous intraplate residual velocities within this region. Three of four groups were identified in the Azores, highlighting the African-Nubian-Eurasian diffuse plate boundary in this region. Furthermore, in the Canary Islands, two distinct kinematic behaviours were detected, possibly due to the activity along a previously detected tectonic fault between Tenerife and Gran Canaria, where some stations have similar intraplate residuals to those at Madeira and Cape Verde stations, while others have similar intraplate residuals to those of continental stations. Finally, all stations on oceanic crust, except Cape Verde, present recent ground subsidence which may be attributed to isostatic adjustment.
      PubDate: 2021-01-01
       
  • A data-driven method for time-varying wavelet extraction based on the
           local frequency spectrum

    • Free pre-print version: Loading...

      Abstract: Seismic wavelet extraction always plays a central role in high-resolution seismic processing. Conventional methods assume that seismic data are stationary when a constant wavelet is considered, which ignores the time-varying characteristics of seismic wavelets. In reality, seismic data are nonstationary because of attenuation, scattering, and other physical processes during propagation, which means that the frequency spectrum of seismic signal changes from shallow to deep formations. We have developed a time-varying wavelet extraction method by using a highly energy-concentrated time-frequency representation technique. Time-varying wavelets are generated according to the local frequency spectrum at every instant. In addition, because the estimations of parameters for wavelet extraction are fully data-driven, the results of the proposed method are more accurate and suitable for the nonstationary nature of actual seismic data. Synthetic tests indicate the reliability and robustness of the proposed method, even under noise contamination. By applying the time-varying wavelet extracted using the proposed method to seismic inversion on a field data example, we obtain the deconvolution result with improved resolution and a better fit to the well-log reflectivity compared to that by using conventional wavelet extraction methods.
      PubDate: 2021-01-01
       
  • A new univariate deformation analysis approach considering displacements
           as model errors

    • Free pre-print version: Loading...

      Abstract: In Conventional Deformation Analysis (CDA), at least two different epochs are adjusted by using the Least Squares Estimation (LSE) method and compared statistically. The effect of the geometry of the network is an essential part of the adjustment model and the LSE method smears the effects of the displaced point over the other nondisplaced points. In this study, to remove these spoiling effects and to increase the reliability of the deformation analysis, a new approach is introduced. This approach depends on the analysis of the differences between observations of the two epochs, and also considers the principles of the model error approach. All possible combinations of the differences of the observations are considered as model errors in Gauss-Markov model and the estimated model error for the combination, that has the smallest variance, is compared with a critical value to answer the question whether it is significant or not. To compare the results of the new approach with the CDA, the Monte Carlo simulation technique and mean success rate are used in a leveling network. As a consequence, according to the simulation results, the new approach is better than the CDA by 7.6% and 9.7% for one and two displaced points, respectively, when the deformation network is designed as a subnetwork.
      PubDate: 2021-01-01
       
  • Post-stack seismic data interpolation using a fast non-local similarity
           matching algorithm

    • Free pre-print version: Loading...

      Abstract: In the process of seismic data acquisition, there are often missing seismic traces in seismic records, so it is necessary to reconstruct the missing data to provide high-quality data for subsequent seismic data migration and reservoir inversion. Traditional interpolation methods for post-stack seismic data are based on the sparse constraint in the frequency-wavenumber (f-k) domain. However, the data completed using the interpolation method usually leads to the loss of some weak signals when the dip of the post-stack seismic profile is complex. In this paper, the missing data could be regarded as the result of irregular noise with the same waveform and the original signal but with the opposite polarity. The non-local similarity in the denoising algorithm is introduced as a low-rank promoting transform of the low-rank regularization term, and an interpolation method based on non-local similarity is proposed (NLS-WNNM). Furthermore, a fast matching algorithm is developed to search and match the non-local similarity of missing seismic traces (abbreviation FNLS-WNNM), which reduces the loss of weak signals during interpolation. The traditional interpolation method based on f-k domain is compared with the NLS-WNNM to highlight the advancement of the method. Finally, the interpolation test applied to field data confirmes the robustness of the proposed method.
      PubDate: 2021-01-01
       
  • Mantle deformation and seismic anisotropy beneath Northeast India inferred
           from SKKS birefringence

    • Free pre-print version: Loading...

      Abstract: The present study produces very new SKKS splitting measurements from the Northeast India, suggesting the region as tectonically more heterogeneous and complex in nature. It fills the gap of anisotropic parameters from an epicentral range of 140°–180° in order to understand the lithospheric deformation patterns of the terrain in a better way. The splitting parameters namely polarisation direction of fast waves (ϕ) and delay time are the manifestation of anisotropic effects of a medium. The present SKKS splitting measurements from nine broadband seismic stations in Northeast India incorporate new understandings of deformation patterns for this region. At the Himalayan collision zone and sub-Himalayan region, the deformation pattern showing a perfect alignment of the ϕ parallel to the collisional arc (Main Boundary Thrust, Main Central Thrust), suggests that a localized strain derived from N-S Indo-Eurasian collision is the major source behind its complex tectonics. The SKKS splitting measurements at Assam foredeep region streamline the effect of Kopili fault in controlling the deformation patterns in a NW-SE direction. There is a significant difference in anisotropic behaviour of stations at the northern Shillong plateau compared to the stations at its southern proximity. The absolute plate motion (APM) parallel to ϕ in northern fringe of the plateau strictly indicates the influence of asthenospheric flow, which in turn is driven by APM of Indian plate in a no net rotation reference frame. On the other hand, major regional structures like the Dauki and Dapsi faults control the anisotropic pattern at the southern extremity of this plateau.
      PubDate: 2021-01-01
       
  • Effect of a high-resolution global crustal model on gravimetric geoid
           determination: a case study in a mountainous region

    • Free pre-print version: Loading...

      Abstract: A precise gravimetric geoid model is determined by using Stokes formula assuming that there is no topography above the geoid. Then, the geoid model is simply corrected by considering the constant crustal density of 2670 kg m−3 for topographical mass. In fact, the actual density of topographical mass differs about ±20% from the constant value. Recently a global crustal density model within 30″ resolution has been released by the University of New Brunswick in Canada. The paper is devoted to the study of the effect of using this model on the accuracy of gravimetric geoid in a mountainous region in Turkey. Numerical results prove that the differences in the geoid height due to this model may reach up to several decimetres, which should not be ignored in a precise geoid modelling with 1-cm geoid. Thus, it is concluded that the effect of topographical density variations, contained in this model, is significant and should be taken into account in precise geoid determination, particularly in mountainous regions.
      PubDate: 2020-10-01
       
  • Rate of seismic deformation in the Gulf of Aqaba inferred from
           moment-tensor summation

    • Free pre-print version: Loading...

      Abstract: This study aims to quantify the rate of coseismic deformation in the Gulf of Aqaba. Earthquake catalogue, Gutenberg-Richter relationship and fault plane solutions were integrated to measure the size and shape of deformation using the moment-tensor summation technique. First, the Gutenberg-Richter relationship was established using seismicity data from the period of 1964–2019. Then, the moment-tensor summation based on 44 focal mechanism solutions was used to calculate the shape of deformation. The eigenvalues of moment-tensor reflect the diversity of focal mechanism solutions that alternate from normal to strike-slip fault styles in the deformation zone. The analysis reveals a dominant shear deformation in the Gulf of Aqaba that extends in a direction of N42.2°E at a rate of 2.6 ± 0.04 mm yr−1and shortens in the direction of N305.2°E at a rate of 2.0 ± 0.02 mm yr−1. These results suggest that the active deformation occurring in the Gulf of Aqaba is due to the relative tectonic movements between the Arabian and African plates, as well as Sinai subplate.
      PubDate: 2020-10-01
       
  • Stable optimization of finite-difference operators for seismic wave
           modeling

    • Free pre-print version: Loading...

      Abstract: The finite difference scheme is now widely used in the reverse time migration and full waveform inversion. Their results are dependent on the accuracy of finite difference operators. In this paper, we combine the cosine function with the original window function to construct a new window function, in order to obtain higher precision finite difference operators. The absolute error curves of the optimized finite difference operators are close to zero for low wavenumbers. In other words, we do not observe an oscillating curve of absolute errors produced by other optimized methods. In order to overcome the limitations of a single graphics processing unit (GPU), we developed the multiple-GPU method for the elastic wave equation. Numerical experimental results show that our new window function can control the numerical dispersion better than the binomial window and scaled binomial window, and the multiple-GPU computation is very stable.
      PubDate: 2020-10-01
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 35.172.217.174
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-