Are European national borders visible from space?

With every expansion of the European Union the relevance of national borders is decreasing. Free movement of persons inside the European Union makes travelling very convenient and in most cases no country borders are perceived. But how do these look from space?

To answer this question, we used European Sentinel-2 satellite data to have a closer look to one of the – historically – most significant borders in Europe, the former Iron Curtain between Austria and the Czech Republic. 

The basic idea was to make use of the strengths of Sentinel-2 imagery that is widely used for agricultural applications due it its high temporal revisiting time of five days. By analysing phenological statistics based on biophysical parameters, field parcel boundaries on both sides of the border could be visualised. With the method, two contrasting agricultural management practices in both countries can be demonstrated: the parcels in the Czech Republic are much larger due to the historical collectivisation of agricultural during the communist era. Agricultural areas in Austria however are more scattered and show a finer and smaller-scaled structure. Due to the convergence of these two management practices, a clear border can be observed from space and uncovers that at least natural borders still do exist.