Sub-cm consistency of leveled normal heights, GNSS positions and quasigeoid in the Harz test area

摘要

Normal heights can be determined without spirit leveling by combining GNSS heights with a quasigeoid model. The resulting accuracy depends on the quality of the quasigeoid model and on the realization of the GNSS heights. Investigations on this topic are timely because of the ongoing modernization of the height system in Germany. In the Harz mountain range, a sub-cm accuracy validation data set has been established in two GNSS campaigns at stations of the first order leveling network. We used height residuals from GNSS heights, GCG05 quasigeoid heights and DHHN92 normal heights to quantify measurement and modeling errors. The residuals have a very low RMS of 4,9 mm. By including two astrogeodetic quasigeoid profiles we could mutually check different types of residuals and show that the largest contribution to the height residuals (typically about 5 mm) is due to station-dependent GNSS errors while the quasigeoid errors are smaller. We conclude that sub-cm consistency of GNSS positioning, normal heights and quasigeoid model can be achieved, even under rather difficult conditions of a mountain range. This seems internationally relevant as for many countries height residuals are reported that are considerably larger which may be due to the inferior quality of fundamental networks.