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  • 1
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    Regional gravity field refinement for (quasi-) geoid determination based on spherical radial basis functions in Colorado (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-14
    Description: This study presents a solution of the ‘1 cm Geoid Experiment’ (Colorado Experiment) using spherical radial basis functions (SRBFs). As the only group using SRBFs among the fourteen participated institutions from all over the world, we highlight the methodology of SRBFs in this paper. Detailed explanations are given regarding the settings of the four most important factors that influence the performance of SRBFs in gravity field modeling, namely (1) the choosing bandwidth, (2) the locations of the SRBFs, (3) the type of the SRBFs as well as (4) the extensions of the data zone for reducing the edge effect. Two types of basis functions covering the same spectral range are used for the terrestrial and the airborne measurements, respectively. The non-smoothing Shannon function is applied to the terrestrial data to avoid the loss of spectral information. The cubic polynomial (CuP) function which has smoothing features is applied to the airborne data as a low-pass filter for filtering the high-frequency noise. Although the idea of combining different SRBFs for different observations was proven in theory to be possible, it is applied to real data for the first time, in this study. The RMS error of our height anomaly result along the GSVS17 benchmarks w.r.t the validation data (which is the mean results of the other contributions in the ‘Colorado Experiment’) drops by 5% when combining the Shannon function for the terrestrial data and the CuP function for the airborne data, compared to those obtained by using the Shannon function for both the two data sets. This improvement indicates the validity and benefits of using different SRBFs for different observation types. Global gravity model (GGM), topographic model, the terrestrial gravity data, as well as the airborne gravity data are combined, and the contribution of each data set to the final solution is discussed. By adding the terrestrial data to the GGM and the topographic model, the RMS error of the height anomaly result w.r.t the validation data drops from 4 to 1.8 cm, and it is further reduced to 1 cm by including the airborne data. Comparisons with the mean results of all the contributions show that our height anomaly and geoid height solutions at the GSVS17 benchmarks have an RMS error of 1.0 cm and 1.3 cm, respectively; and our height anomaly results give an RMS value of 1.6 cm in the whole study area, which are all the smallest among the participants.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:526 ; ‘1 cm Geoid Experiment’ ; Spherical radial basis functions ; Regional geoid modeling ; Heterogeneous data combination
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 2
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    The DGFI geoid based on spherical radial basis functions for the Colorado Experiment: ColSRBF-DGFI2019 (2019)
    GFZ Data Services
    Details
    Publication Date: 2021-10-27
    Description: Abstract
    Description: The ColSRBF-DGFI2019 gravimetric geoid model has been computed by the Deutsches Geodätisches Forschungsinstitut (DGFI), Technical University of Munich (TUM). It has been worked out in the frame of the International Association of Geodesy Joint Working Group 2.2.2 "The 1 cm geoid experiment" and the so called "Colorado experiment". The area covered by the model is 251°E ≤ longitude ≤ 257°E, 36°N ≤ latitude ≤ 39°N with a grid spacing of 1' in both latitude and in longitude. Input data include terrestrial and airborne gravity observations, both used with their original observation sites. The computation method is based on spherical radial basis functions (SRBFs), using the Shannon function and the Cubic Polynomial (CuP) function for the terrestrial and airborne data, respectively. The computation is performed in the framework of a remove-compute-restore procedure, taking XGM2016 as global gravity model and Earth2014 / ERTM2160 for the topographic gravity effects. The terrestrial and airborne observations are combined within a parameter estimation procedure, and the relative weight between these two types of observations are determined by the method of variance component estimation (VCE). The classical formula by Heiskanen and Moritz (1967) is used for quasi-geoid to geoid conversion. The accuracy of the geoid model, when compared against GSVS17 GPS/leveling, is equal to 3.0 cm. The geoid model is provided in ISG format 2.0 (ISG Format Specifications), while the file in its original data format is available at the model ISG webpage.
    Description: Other
    Description: The International Service for the Geoid (ISG) was founded in 1992 (as International Geoid Service - IGeS) and it is now an official service of the International Association of Geodesy (IAG), under the umbrella of the International Gravity Field Service (IGFS). The main activities of ISG consist in collecting, analysing and redistributing local and regional geoid models, as well as organizing international schools on the geoid determination (Reguzzoni et al., 2021).
    Keywords: Geodesy ; Geoid model ; ISG ; Spherical radial basis functions ; Colorado experiment ; EARTH SCIENCE 〉 SOLID EARTH 〉 GEODETICS 〉 GEOID CHARACTERISTICS ; EARTH SCIENCE 〉 SOLID EARTH 〉 GRAVITY/GRAVITATIONAL FIELD 〉 GRAVITY
    Type: Dataset , Dataset
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    DATA GFZ
  • 3
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    The DGFI quasi-geoid based on spherical radial basis functions for the Colorado Experiment: ColSRBF-DGFI2019 (2019)
    GFZ Data Services
    Details
    Publication Date: 2021-12-08
    Description: Abstract
    Description: The ColSRBF-DGFI2019 gravimetric quasi-geoid model has been computed by the Deutsches Geodätisches Forschungsinstitut (DGFI), Technical University of Munich (TUM). It has been worked out in the frame of the International Association of Geodesy Joint Working Group 2.2.2 "The 1 cm geoid experiment" and the so called "Colorado experiment". The area covered by the model is 251°E ≤ longitude ≤ 257°E, 36°N ≤ latitude ≤ 39°N with a grid spacing of 1' in both latitude and in longitude. Input data include terrestrial and airborne gravity observations, both used with their original observation sites. The computation method is based on spherical radial basis functions (SRBFs), using the Shannon function and the Cubic Polynomial (CuP) function for the terrestrial and airborne data, respectively. The computation is performed in the framework of a remove-compute-restore procedure, taking XGM2016 as global gravity model and Earth2014 / ERTM2160 for the topographic gravity effects. The terrestrial and airborne observations are combined within a parameter estimation procedure, and the relative weight between these two types of observations are determined by the method of variance component estimation (VCE). The accuracy of the quasi-geoid model, when compared against GSVS17 GPS/leveling, is equal to 2.9 cm. The geoid model is provided in ISG format 2.0 (ISG Format Specifications), while the file in its original data format is available at the model ISG webpage.
    Description: Other
    Description: The International Service for the Geoid (ISG) was founded in 1992 (as International Geoid Service - IGeS) and it is now an official service of the International Association of Geodesy (IAG), under the umbrella of the International Gravity Field Service (IGFS). The main activities of ISG consist in collecting, analysing and redistributing local and regional geoid models, as well as organizing international schools on the geoid determination (Reguzzoni et al., 2021).
    Keywords: Geodesy ; Geoid model ; ISG ; Spherical radial basis functions ; Colorado experiment ; EARTH SCIENCE 〉 SOLID EARTH 〉 GEODETICS 〉 GEOID CHARACTERISTICS ; EARTH SCIENCE 〉 SOLID EARTH 〉 GRAVITY/GRAVITATIONAL FIELD 〉 GRAVITY
    Type: Dataset , Dataset
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    DATA GFZ
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