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Various research topics in geosciences such as gravity modelling, terrain correction and ocean circulation, require high resolution and accuracy global elevations for land topography, bathymetry, and ice thickness that refer to a consistent vertical datum. Unfortunately, most of the existing DEMs do not provide such solutions for Earth relief layers with the same resolution globally. To overcome this deficiency, we merged various DEMs published in the recent years and compiled an up-to-date global solution. We provide 30 arcsecond grid suite for relief layers and land-type masks which have been substantially improved w.r.t. the grids in literature. The quality of the merged surface elevation is assessed against the GNSS heights at about globally distributed 22000 stations. The merged surface model shows a reduction in standard deviation of a factor of three compared to other commonly used DEMs. Other evaluations are performed over land-ice and oceans which supports the advancement of GDEMM2024. The improvements are due to the accuracy and coverage of the original input data, updated land-type masks and merging methodology., (© 2024. The Author(s).)

When applying the Global Navigation Satellite System (GNSS) for precise kinematic positioning in airborne and shipborne gravimetry, multiple GNSS receiving equipment is often fixed mounted on the kinematic platform carrying the gravimetry instrumentation. Thus, the distances among these GNSS antennas are known and invariant. This information can be used to improve the accuracy and reliability of the state estimates. For this purpose, the known distances between the antennas are applied as a priori constraints within the state parameters adjustment. These constraints are introduced in such a way that their accuracy is taken into account. To test this approach, GNSS data of a Baltic Sea shipborne gravimetric campaign have been used. The results of our study show that an application of distance constraints improves the accuracy of the GNSS kinematic positioning, for example, by about 4 mm for the radial component.