The Greenland Ice Sheet is increasingly losing mass due to a warming climate and is a major contributor to sea level rise. In the percolation zone, there is a net mass gain, but surface melt occurs during the summer months. Meltwater can percolate into the firn, filling free pore space and buffering its contribution to sea level rise. However, ice layers within the firn matrix inhibit meltwater percolation and reduce the firn's buffering capacity. Understanding these processes is crucial for assessing the ice sheet's mass balance, and they are studied using various methods, including modelling and remote sensing. In-situ measurements, such as firn cores, are essential for their validation and improving the general understanding of the firn processes. Here, the spatial representativeness of firn cores is assessed by comparing them with ground-penetrating radar (GPR) surveys from four sites with automatic weather stations of the Greenland Climate Network (GC-Net) in the percolation zone. Strong radar reflectors are traced using an automated peak detection method and analysed across different segments of each site. The comparison between the segments reveals variations and similarities across the study areas. Results indicate that thick ice layers and major density changes vary in depth but are continuous over the surveyed areas, supporting the representativeness of firn cores over several hundred metres. However, thin ice layers and percolation features are more spatially variable, and the applied method is not able to find small-scale variations of these discontinuous ice structures within the firn matrix. No influence of the annual maintenance work around the automatic weather stations on the firn structure is found. Additionally, the change in the firn structure over one year is analysed using the SNOWPACK model and the results are compared to firn core and temperature observations. While the model performs well at some sites, significant discrepancies exist at others, highlighting the challenges of accurately modelling the diverse percolation zone of the Greenland Ice Sheet.