Program for the Interpolation of the Astrogeodetic Deflections of the Vertical

conference proceedings

English

The astrogeodetic deflections of the vertical are suitable for independent testing of existing Earth gravity models. Their advantage is that they can be determined directly from the combination of the astronomic and geodetic measurements. Their disadvantage is difficult determination (measurement is carried out at night), hence there are only a few available. These problems can be solved by interpolation of the astrogeodetic deflections of the vertical. In this work have used the topographic deflections of the vertical for the interpolation. These can be computed from the digital terrain model. For this calculation and subsequent interpolation was written a program in Matlab. The first test of the program was performed on the AGNES network, which is located around the city center of Brno. Network AGNES has 34 points and its density is about 1 point per km2 and all points have determined astrogeodetic deflections of the vertical. On the territory of AGNES network are other 13 points with determined astrogeodetic deflections of vertical, but these points are not included in the AGNES network. The deflections of the vertical were determined on all points by the same method and with the same accuracy 0,20´´ - 0,30´´. On all points were computed topographic deflections of the vertical and results from Matlab were compared with results from Gravsoft. The root mean square errors were 0,01´´ in the meridian and the first vertical component of the topographic deflections of the vertical. The integration window radius was 9 km. Two versions of test were performed. In the first test version were chosen for the test points 13 points that are not included in the AGNES network. On these points was detected an improvement of root mean square errors of 42% in the median component and 51% of the first vertical component of the astrogeodetic deflections of the vertical compared with the computation without using the topographic deflections of the vertical. In the second test version were selected testing points in a way that the network of known points had a density of 1 point per 2 km2. In this version of computation was detected an improvement of root mean square errors of 43% in the meridian component and 40% in the first vertical of the astrogeodetic deflections of the vertical compared with the computation without using the topographic deflections of the vertical.

Interpolation, AGNES, Astrogeodetic deflections of the vertical, Matlab

KRATOCHVÍL, R.

25. 5. 2017

978-83-7717-259-9

XXXIV Sejmik SNK

1.