Transformation of global spherical harmonic models of the gravity field to a local adjusted spherical cap harmonic model

2011 ◽  
Vol 6 (2) ◽  
pp. 375-381 ◽  
Author(s):  
Ghadi K. A. Younis ◽  
Reiner Jäger ◽  
Matthias Becker
Keyword(s):  
Gravity Field ◽  
Spherical Harmonic ◽  
Harmonic Model ◽  
Spherical Cap ◽  
Spherical Harmonic Models ◽  
Spherical Cap Harmonic Model

scholarly journals A Spherical Cap Harmonic Model of the Satellite Magnetic Anomaly Field Over China and Adjacent Areas.

1992 ◽  
Vol 44 (3) ◽  
pp. 243-252 ◽  
Author(s):  
Zhen-chang AN ◽  
Shi-zhuang MA ◽  
Dong-hai TAN ◽  
D. R. BARRACLOUGH ◽  
D. J. KERRIDGE
Keyword(s):  
Magnetic Anomaly ◽  
Harmonic Model ◽  
Spherical Cap ◽  
Anomaly Field ◽  
Spherical Cap Harmonic Model

Spherical cap harmonic model for mapping and predicting regional TEC

GPS Solutions ◽  
2010 ◽  
Vol 15 (2) ◽  
pp. 109-119 ◽  
Author(s):  
Jingbin Liu ◽  
Ruizhi Chen ◽  
Zemin Wang ◽  
Hongping Zhang
Keyword(s):  
Harmonic Model ◽  
Spherical Cap ◽  
Spherical Cap Harmonic Model

High-resolution GRACE Monthly Gravity Field Solutions Expressed as Geopotential Coefficients

2021 ◽  
Author(s):  
Qiujie Chen ◽  
Jürgen Kusche ◽  
Yunzhong Shen ◽  
Xingfu Zhang
Keyword(s):  
High Resolution ◽  
Gravity Field ◽  
Spatial Resolution ◽  
Spherical Harmonic ◽  
Regularization Method ◽  
A Priori ◽  
Spatial Constraints ◽  
Spherical Harmonic Models ◽  
Priori Information ◽  
Geopotential Coefficients

<p>The commonly used filters (e.g. Gaussian smoothing, decorrelation and DDK filtering) applied to GRACE spherical harmonic gravity field solutions generally lead to reduced resolution, signal damping and leakage. This work is dedicated to improving spatial resolution and reducing signal damping by developing a regularization method with spectral constraints to spherical harmonics. Before constructing the spectral constraints, we create spatial constraints over global grids (covering lands, oceans and the boundaries between lands and oceans) from the a priori information of GRACE spherical harmonic models. Since we are solving geopotential coefficients rather than mascon grids, we further transfer the spatial constraints into the spectral domain according to the law of variance-covariance propagation, leading to spectral constraints regarding geopotential coefficients. In our work, the regularization method with spectral constraints was demonstrated to have comparable ability as mascon modelling method to enhance the spatial resolution and signal power besides reducing signal leakage. Applying the presented method with spatial constraints, we produced the first time series of high-resolution gravity field solutions expressed as geopotential coefficients complete to degree and order 180. Our analyses over the global and regional areas show that our high-resolution solutions are in good agreement with CSR and JPL mascon solutions.</p>

A Preliminary Study on Mapping the Regional Ionospheric TEC Using a Spherical Cap Harmonic Model in High Latitudes and the Arctic Region

2010 ◽  
Vol 9 (1) ◽  
pp. 22-32 ◽  
Author(s):  
Jingbin Liu ◽  
Ruizhi Chen ◽  
Heidi Kuusniemi ◽  
Zemin Wang ◽  
Hongping Zhang ◽  
...  
Keyword(s):  
Arctic Region ◽  
The Arctic ◽  
High Latitudes ◽  
Harmonic Model ◽  
Spherical Cap ◽  
Preliminary Study ◽  
Spherical Cap Harmonic Model ◽  
The Arctic Region

Local Quasi-Geoid Refinement Based on Spherical Cap Harmonic Model

2012 ◽  
Vol 226-228 ◽  
pp. 1947-1950 ◽  
Author(s):  
Jin Yun Guo ◽  
Shu Yang Wang ◽  
Guo Wei Li ◽  
Wei Hua Mao ◽  
Yuan Ming Ji
Keyword(s):  
Height Anomaly ◽  
Practical Case ◽  
Harmonic Model ◽  
Geoid Model ◽  
Normal Height ◽  
Spherical Cap ◽  
Geodetic Height ◽  
Gps Leveling ◽  
Spherical Cap Harmonic Model ◽  
Selection Of

The local quasi-geoid model up to centimeter precision has became the basic requirement for the development of modern surveying and mapping science. There are a variety of models can be used for the quasi-geoid refinement, including the spherical cap harmonic model (SCH). This paper studies the theory of SCH to get the spherical cap harmonic expression to fit the height anomaly in the least squares sense, which is to achieve the transformation between the geodetic height and the normal height. We also discuss the selection of the maximum model degree in local region. The practical case is studied to refine the local quasi-geoid model with SCH using GPS/leveling data at 85 points. The results indicate that the local quasi-geoid model can reach 3 centimeter-level at the internal and external fitting precision.

Gravity Field Recovery and Observation Noise Separation from Simultaneous Laser Ranging Interferometer and K-Band Ranging System Measurements

2020 ◽  
Author(s):  
Andreas Kvas ◽  
Saniya Behzadpour ◽  
Torsten Mayer-Guerr
Keyword(s):  
Gravity Field ◽  
Spherical Harmonic ◽  
Uncertainty Propagation ◽  
Stochastic Modelling ◽  
Laser Ranging ◽  
Polar Regions ◽  
Data Types ◽  
Covariance Functions ◽  
Gravity Field Recovery ◽  
K Band

<p>The unique instrumentation of GRACE Follow-On (GRACE-FO) offers two independent inter-satellite ranging systems with concurrent observations. Next to a K-Band Ranging System (KBR), which has already been proved during the highly-successfully GRACE mission, the GRACE-FO satellites are equipped with an experimental Laser Ranging Interferometer (LRI), which features a drastically increased measurement precision compared to the KBR. Having two simultaneous ranging observations available allows for cross-calibration between the instruments and, to some degree, the separation of ranging noise from other sources such as noise in the on-board accelerometer (ACC) measurements.  </p> <p>In this contribution we present a stochastic description of the two ranging observation types provided by GRACE-FO, which also takes cross-correlations between the two observables into account. We determine the unknown noise covariance functions through variance component estimation and show that this method is, to some extent, capable of separating between KBR, LRI, and ACC noise. A side effect of this stochastic modelling is that the formal errors of the spherical harmonic coefficients fit very well to empirical estimates, which is key for combination with other data types and uncertainty propagation. We further compare the gravity field solutions obtained from a combined least-squares adjustment to KBR-only and LRI-only results and discuss the differences between the time series with a focus on gravity field and calibration parameters. Even though, at the moment, global statistics only show a minor improvement when using LRI ranging measurements instead of KBR observations, some parts of the spectrum and geographic regions benefit significantly from the increased measurement accuracy of the LRI. Specifically, we see a higher signal-to-noise ratio in low spherical harmonic orders and the polar regions.</p>

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