scholarly journals Evaluating Accuracy of HY-2A/GM-Derived Gravity Data With the Gravity-Geologic Method to Predict Bathymetry

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhijie Wei ◽  
Jinyun Guo ◽  
Chengcheng Zhu ◽  
Jiajia Yuan ◽  
Xiaotao Chang ◽  
...  
Keyword(s):  
Gravity Data ◽  
Bottom Topography ◽  
Gravity Anomalies ◽  
Processing Method ◽  
Ocean Bottom ◽  
Least Squares Collocation ◽  
Geological Structures ◽  
Data Processing Method ◽  
First Time ◽  
Assessment Result

For the first time, HY-2A/GM-derived gravity anomalies determined with the least-squares collocation method and ship-borne bathymetry released from the National Centers for Environmental Information (NCEI) are used to predict bathymetry with the gravity-geologic method (GGM) over three test areas located in the South China Sea (105–122°E, 2–26°N). The iterative method is used to determine density contrasts (1.4, 1.5, and 1.6 g/cm3) between seawater and ocean bottom topography, improving the accuracy of GGM bathymetry. The results show that GGM bathymetry is the closest to ship-borne bathymetry at check points, followed by SRTM15+V2.0 model and GEBCO 2020 model. It is found that in a certain range, the relative accuracy of GGM bathymetry tends to improve with the increase of depth. Different geological structures affect the accuracy of GGM bathymetry. In addition, the influences of gravity anomalies and data processing method on GGM bathymetry are analyzed. Our assessment result suggests that GGM can be widely applied to bathymetry prediction and that HY-2A/GM-derived gravity data are feasible with good results in calculating ocean depth.

A priori noise and regularization in least squares collocation of gravity anomalies

2013 ◽  
Vol 62 (2) ◽  
pp. 199-216 ◽  
Author(s):  
Wojciech Jarmołowski
Keyword(s):  
Least Squares ◽  
Spatial Resolution ◽  
Gravity Data ◽  
A Priori ◽  
Gravity Anomalies ◽  
Geopotential Model ◽  
Large Set ◽  
Least Squares Collocation ◽  
Gravity Field Model ◽  
Two Parameters

Abstract The paper describes the estimation of covariance parameters in least squares collocation (LSC) by the cross-validation (CV) technique called leave-one-out (LOO). Two parameters of Gauss-Markov third order model (GM3) are estimated together with a priori noise standard deviation, which contributes significantly to the covariance matrix composed of the signal and noise. Numerical tests are performed using large set of Bouguer gravity anomalies located in the central part of the U.S. Around 103 000 gravity stations are available in the selected area. This dataset, together with regular grids generated from EGM2008 geopotential model, give an opportunity to work with various spatial resolutions of the data and heterogeneous variances of the signal and noise. This plays a crucial role in the numerical investigations, because the spatial resolution of the gravity data determines the number of gravity details that we may observe and model. This establishes a relation between the spatial resolution of the data and the resolution of the gravity field model. This relation is inspected in the article and compared to the regularization problem occurring frequently in data modeling.

PENGARUH ETIKA PEGAWAI, PELAYANAN PUBLIK DAN REFORMASI BIROKRASI TERHADAP PENERAPAN ZONA INTEGRITAS PADA LAPAS MAKASSAR

2020 ◽  
Vol 2 (1) ◽  
pp. 13-15
Author(s):  
Adi Sucipto ◽  
Hasanuddin Remmang ◽  
Haeruddin Saleh
Keyword(s):  
Regression Analysis ◽  
Data Processing ◽  
Multiple Regression Analysis ◽  
Multiple Regression ◽  
Random Sampling ◽  
Public Services ◽  
Simple Random Sampling ◽  
Processing Method ◽  
Data Processing Method

Penelitian ini bertujuan menguji pengaruh Etika Pegawai, Pelayanan Publik dan Reformasi Birokrasi terhadap Penerapan Zona Integritas. Pengaruh Etika Pegawai, Pelayanan Publik dan Reformasi Birokrasi terhadap Penerapan Zona Integritas pada Lembaga Pemasyarakatan Kelas I Makassar Responden dalam penelitian ini adalah Pengunjung dan keluarga nara-pidana Lembaga Pemasyarakatan Kelas I Makassar. Jumlah pengunjung yang menjadi sampel penelitian ini adalah 55 orang. Metode penentuan sampel yang digunakan dalam penelitian ini adalah Simple Random Sampling, sedangkan metode pengolahan data yang digunakan peneliti adalah analisis regresi berganda. Hasil penelitian ini menunjukkan bahwa Etika Pegawai dan Pelayanan Publik berpengaruh signifikan terhadap Penerapan Zona Integritas di Lembaga Pemasyarakatan Kelas I Makassar.     This study examines the effect of employee ethics and the improvement of public services on the implementation of the integrity zone. The effect of employee ethics, and improvement of public services on the implementation of integrity zone on Lembaga Pemasyarakatan Kelas 1 Makassar. Respondents in this study were Makassar class in penitentiary visitors. the number of visitors who sampled this study was 55 people. the method of determining the sample used in this study is simple random sampling, while the data processing method used by researchers is multiple regression analysis. the results of this study indicate that employee ethics and public services have a significant effect on the implementation of the integrity zone in Makassar class in penitentiary.

EAST-NBI experimental data processing method based on improved OPTICS algorithm

2021 ◽  
Vol 172 ◽  
pp. 112737
Author(s):  
Jinxin Wang ◽  
Zhimin Liu ◽  
Yuanzhe Zhao ◽  
Yahong Xie ◽  
Yuanlai Xie
Keyword(s):  
Experimental Data ◽  
Data Processing ◽  
Processing Method ◽  
Experimental Data Processing ◽  
Data Processing Method

scholarly journals Joint Gravity and Seismic Reflection Methods to Characterize the Deep Aquifers in Arid Ain El Beidha Plain (Central Tunisia, North Africa)

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1310
Author(s):  
Hajer Azaiez ◽  
Hakim Gabtni ◽  
Mourad Bédir
Keyword(s):  
Seismic Reflection ◽  
Large Scale ◽  
Seismic Analysis ◽  
Gravity Data ◽  
Geophysical Methods ◽  
Gravity Anomalies ◽  
Integrated Approach ◽  
Central Tunisia ◽  
Deep Aquifers ◽  
Advanced Analysis

Electric resistivity sounding and tomography, as well as electromagnetic sounding, are the classical methods frequently used for hydrogeological studies. In this work, we propose the development and implementation of an original integrated approach using the unconventional hydro–geophysical methods of gravity and seismic reflection for the fast, large–scale characterization of hydrogeological potential using the Ain El Beidha plain (central Tunisia) as an analogue. Extending the values of vintage petroleum seismic reflection profiles and gravity data, in conjunction with available geological and hydrogeological information, we performed an advanced analysis to characterize the geometry of deep tertiary (Oligocene and Eocene) aquifers in this arid area. Residual and tilt angle gravity maps revealed that most gravity anomalies have a short wavelength. The study area was mainly composed of three major areas: the Oued Ben Zitoun and Ain El Beidha basins, which are both related to negative gravity trends corresponding to low–density subsiding depocenters. These basins are separated by an important NE–SW trend called “El Gonna–J. El Mguataa–Kroumet Zemla” gravity high. Evaluation of the superposition of detected lineaments and Euler deconvolution solutions’ maps showed several NE–SW and N–S relay system faults. The 3D density inversion model using a lateral and vertical cutting plane suggested the presence of two different tectonic styles (thin VS thick). Results from the gravity analysis were in concordance with the seismic analysis. The deep Oligocene and Eocene seismic horizons were calibrated to the hydraulic wells and surrounding outcrops. Oligocene and Eocene geological reservoirs appear very fractured and compartmented. The faulting network also plays an important role in enhancing groundwater recharge process of the Oligocene and Eocene aquifers. Finally, generated isochron maps provided an excellent opportunity to develop future comprehensive exploration surveys over smaller and more favorable areas’ sub–basins.

Typhoon-Induced Microseisms around the South China Sea

2020 ◽  
Vol 91 (6) ◽  
pp. 3454-3468
Author(s):  
Seongjun Park ◽  
Tae-Kyung Hong
Keyword(s):  
South China Sea ◽  
South China ◽  
Bottom Topography ◽  
Pressure Change ◽  
Ocean Waves ◽  
The South China Sea ◽  
Ocean Bottom ◽  
The South ◽  
China Sea ◽  
Regional Factors

Abstract Microseisms in frequencies of 0.05–0.5 Hz are a presentation of solid earth response to the ocean waves that are developed by atmospheric pressure change. The South China Sea provides a natural laboratory with a closed ocean environment to examine the influence of regional factors on microseism development as well as the nature of microseisms. The microseisms induced by typhoons crossing over the South China Sea are investigated. Typhoons are typical transient sources of varying strengths and locations. Primary microseisms develop nearly stationary in the northeastern South China Sea for most typhoons, suggesting effective environment for excitation of primary microseisms. Typhoon-induced secondary microseisms develop around the typhoon paths with time delays varying up to one day. Typhoon-induced microseism amplitudes are proportional to the ocean-wave amplitudes in the source regions, decaying with distance. Ocean waves develop following the typhoons for days. The dominant frequency of typhoon-induced microseisms increases with time due to the influence of dispersive ocean waves. The microseisms are affected by regional factors including crustal structures, coastal geometry, ocean depth, and ocean-bottom topography.

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