| Abstrakt: |
The Earth’s gravity field tends to change due to various reasons. These are diverse processes occurring inside the Earth or changes initiated by human activity. The increasing accuracy of measurements has enabled to take into consideration fluctuations in the gravity field. The article presents research study on the effect of gravity potential describing variations in the gravity field affecting gravity field elements related to the performed measurements. Due to the effect of the disturbing potential, a change in gravity and the deviation of vertical and equipotential surface deformation have been determined. The paper has analyzed the disturbing effect of the material point or homogeneous sphere and has specified the possibilities of assessing the disturbing effect of any form of the homogeneous body. Based on the tidal potential induced by the celestial body, the disturbing effect of the Moon and Sun onto the Earth’s gravity field has been assessed. The carried out research indicates that the range of deformation changes in the equipotential surface of the Earth’s gravity field induced by the effect of the Moon is equal to 0.4824 m, whereas that of the Sun makes 0.1861 m. The conducted studies prove that, due to the effect of the Moon, the direction of the vertical, in terms of the Earth’s surface, tends to change up to 0.0541", and as a result of the Sun’s effect it could reach 0.0204". Having assessed the Lunisolar effect in the first order vertical network measurements in Lithuania, in a polygon with the perimeter of 451 km, it has been determined that the closing error of normal height difference has decreased by the factor of 1.3. |
