Regional dispersion of potential accessibility quotient at the intra-European and intranational level. Core-periphery pattern, discontinuity belts and distance decay tornado effect

The regional differences in the level of accessibility and GDP per capita in Europe are the subject of many scientific analyses and much applied research. Using the road network for the whole continent and the division of Europe into transport areas on the basis of NUTS 3, we have concentrated on the potential quotient as a research method. The quotient is a ratio of economic and population potential, and its level and spatial distribution differ based on the dimensions of accessibility: spatial scope (intra-European and intra-national) and impedance. Depending on the variants of the above-mentioned accessibility dimensions, we focus on analysis of the core-periphery pattern. Based on a comparison of the level of GDP per capita with the level of potential quotient, we define the discontinuity belts in the cross-border areas and in urban agglomerations, i.e. areas particularly sensitive to migratory movements or commuting to work. In turn, the analysis of regional differences in the level of the potential quotient for different travel durations and, as we call it in the paper, the value of the CATCH-time, leads us to show the so-called tornado effect which is associated with declining spatial polarisation as a result of the extension of trip distribution towards longer trips. The typology presented describing the relationship between GDP per capita and the level of potential quotient at different spatial scales and for different trip durations allows the identification of regions particularly exposed to migration or interregional commuting flows and is a good premise for defining inner peripheries.