## 1 Introduction
Geodetic satellites monitor gravity changes, radar satellites can use InSAR technology to determine displacements or create digital surface models, and optical satellite systems can help monitor the extent of glaciation [16; 13]. Fast and accurate GNSS instruments can monitor the height or movement of glaciers [17; 18; 19]. In the context of Arctic polar research, it is worth remembering [PERSON]'s unique polar expedition on the Fram ship (1893-1896); this was followed in 2019 by an international expedition aboard the modern research ship Polarstern. The aim was the comprehensive mapping of the Arctic and, in particular, research on global warming [20]. Glacier changes related to global warming have been investigated in many other scientific papers [21; 22]. Twenty years ago, in the summer of 2002, geodesist [PERSON] (Figure 1) started a climate research project in Greenland. The main objective was to determine elevations and their changes along a profile across the Greenland ice sheet. A 700 km traverse was surveyed between Tasililaq on the east coast and Ilulissat on the west coast of Greenland (see Figure 2). After his tragic death, however, some members of his expeditions continued his work. This provided another valuable amount of information on the changing Greenland ice sheet. The results from all the expeditions are summarized in the following text. This route was first successfully crossed by the Swiss [PERSON] in 1912. Even if the accuracy of his measurements was only relatively low compared to today's possibilities, the large time difference of more than a hundred years naturally tempts a comparison [18], which is especially interesting in the strongly changing marginal area of the ice sheet. Meanwhile, during the eight expeditions since 2002, the profile was surveyed five times completely and three times partially with high accuracy (see Table 1). The process results in surface elevations with a measurement accuracy of 3-5 cm, from which annual surface changes are derived with similar accuracy. The measurements were carried out between the end of July and the beginning of September. During this period, the summer thaw was ending, while the winter snowfall had not yet begun. It is, therefore, the time of the year when the seasonal variations in ice elevations reach their minimum. Based on GNSS technology progress since the 2015 expedition, the measurement program was changed. Unlike in previous years, not only w \begin{table}
\begin{tabular}{c c c c} \hline
**Year** & **Scientific Director** & **Method of Measurement** & **Remark** \\ \hline
1912 & [PERSON] & barometric & 39 camps: accuracy in the coastal area +/–3-5 m \\
2002 & W. Korth & GPS static & 34 positions; +/–3 cm \\
2006 & W. Korth & GPS static & 34 positions; +/–3 cm \\
2010 & W. Korth & GNSS static & 34 positions; +/–2 cm \\
2012 & W. Korth & GNSS static & only east coast; 17 positions +/–2 cm \\
2015 & W. Korth & GNSS kinematic and static & continuous profile; spot spacing 2–6 m; 700 km; +/–3 cm \\
2017 & W. Korth & GNSS kinematic & continuous pc; spot spacing 2–6 m; approx. 180 km; +/–3 cm \\
2020 & T. Hitigger & GNSS kinematic & continuous pc; spot spacing 2–6 m; approx. 500 km; +/–3 cm \\
2021 & T. Hitigger/. Heim & GNSS kinematic & continuous pc; spot spacing 2–6 m; approx. 680 km; +/–3 cm \\ \hline \end{tabular}
\end{table} 
Table 1: Overview of geoscientific Expeditions on the historic route. Figure 2: Map of Greenland [17] and route of Greenland Korth Expedition (GKE) with walking direction, camps from 2002 and historical camps from 1912. The blue line approximately marks the catchment area of the Helheim and Iluilssat (Jakobshavn) glaciers and the top of the Greenland ice sheet. termined but the measurements were carried out continuously along the entire route at 1-second intervals. Thus, for the first time, a 700 km long profile with a point spacing of less than 2 m is available. The possibilities for comparison with satellite data have thus improved enormously.