Astronomical School’s Report, 2018, Volume 14, Issue 1, Pages 35–41

https://doi.org/10.18372/2411-6602.14.05
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UDC 528.2

Approbation of the global gravity field model constructing method with a non-diagonal normal equations matrix based on the DTU10 gravity anomalies

Marchenko A.N., Lukianchenko Yu.O.

Lviv Polytechnic National University, 79013, Lviv, S. Bandery street 12

Abstract

In this paper we considered approach for the modeling of a global gravitational field using a non-diagonal normal equations matrix. Orthogonal properties are used that are caused due to the uniform location of data on a spherical surface. Two cases of data placement, at the peaks of trapezium and for the central values of the trapezium, and the corresponding orthogonal properties of these cases are considered. The method of dividing the matrix of normal equations into several smaller linearly independent matrices is applied. As a result, certain groups of harmonic coefficients of even and odd orders and degrees were determined. This made it possible to parallelize the calculation process, which greatly reduced the time of execution of this work. This approach can be recommended for scientists involved in gravitational field modeling and have no access to powerful computing clusters, or for constructing of ultrahigh-level models. Such an approach to the definition of harmonic coefficients significantly expands the scope of scientists who could deal with these issues. Three models of the global gravitational field of the Earth 180, 360 and 720 degrees were constructed using the regular grids of 30′ × 30′, 30′ × 30′ and 9′ × 9′ respectively. The obtained models were compared with the model EGM2008 within the spectral amplitudes, which were constructed for each degree of the model of the gravitational field of the Earth and presented for the signal model, the differences between the two signals of the comparable models and the accumulation of such differences. Based on the obtained harmonic coefficients, gravity anomalies were reproduced and compared with the original sets. The standard deviations of the differences between the primary and the calculated anomalies were calculated with next standard deviations 13.21 mGal, 5.36 mGal and 7.52 mGal for models 180, 360 and 720 degrees, respectively. The unit of weight of the mean square error and the covariance matrix were calculated, after this a posteriori estimation of the accuracy of the obtained models was performed. It is shown that according to the anomalies DTU10 it is possible to construct a global gravity field model of the Earth up to 550 degree/order.

Keywords: global gravitational field modeling; gravity anomalies; least squares

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