Abstract
Human development has far-reaching impacts on the surface of the globe. The transformation of natural land cover occurs in different forms, and urban growth is one of the most eminent transformative processes. We analyze global land cover data and extract cities as defined by maximally connected urban clusters. The analysis of the city size distribution for all cities on the globe confirms Zipf’s law. Moreover, by investigating the percolation properties of the clustering of urban areas we assess the closeness to criticality for various countries. At the critical thresholds, the urban land cover of the countries undergoes a transition from separated clusters to a gigantic component on the country scale. We study the Zipf-exponents as a function of the closeness to percolation and find a systematic dependence, which could be the reason for deviating exponents reported in the literature. Moreover, we investigate the average size of the clusters as a function of the proximity to percolation and find country specific behavior. By relating the standard deviation and the average of cluster sizes—analogous to Taylor’s law—we suggest an alternative way to identify the percolation transition. We calculate spatial correlations of the urban land cover and find long-range correlations. Finally, by relating the areas of cities with population figures we address the global aspect of the allometry of cities, finding an exponent δ ≈ 0.85, i.e., large cities have lower densities.
Highlights
In the beginning of the last century, F
In this paper we have elaborated on the influence exerted by the degree of coarsening resolution that is inherent to the definition of city boundaries, on a set of indicators of the scaling, spatial organization, and allometry aspects of urban clusters
For this purpose we implemented a version of the City Clustering Algorithm that takes the curvature of the globe into account and apply it to global satellite based information on the global urban land cover, in combination with pointwise information of populated units worldwide
Summary
In the beginning of the last century, F. In this work we estimate the global city size distribution, based on both, urban land cover and population. For this purpose we apply an orthodromic version [10] of the recently proposed. Defining a city boundary by means of the CCA requires to specifying a distance below which adjacent urban areas are considered to be part of the same cluster.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
