@article{GudipudiRybskiLuedekeetal.2018,
  author    = {Gudipudi, Venkata Ramana and Rybski, Diego and L{\"u}deke, Matthias K. B. and Zhou, Bin and Liu, Zhu and Kropp, J{\"u}rgen},
  title     = {The efficient, the intensive, and the productive},
  series = {Applied Energy},
  volume    = {236},
  journal   = {Applied Energy},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0306-2619},
  doi       = {10.1016/j.apenergy.2018.11.054},
  pages     = {155 -- 162},
  year      = {2018},
  abstract  = {Urban areas play an unprecedented role in potentially mitigating climate change and supporting sustainable development. In light of the rapid urbanisation in many parts on the globe, it is crucial to understand the relationship between settlement size and CO2 emission efficiency of cities. Recent literature on urban scaling properties of emissions as a function of population size has led to contradictory results and more importantly, lacked an in-depth investigation of the essential factors and causes explaining such scaling properties. Therefore, in analogy to the well-established Kaya Identity, we develop a relation combining the involved exponents. We demonstrate that application of this Urban Kaya Relation will enable a comprehensive understanding about the intrinsic factors determining emission efficiencies in large cities by applying it to a global dataset of 61 cities. Contrary to traditional urban scaling studies which use Ordinary Least Squares (OLS) regression, we show that the Reduced Major Axis (RMA) is necessary when complex relations among scaling exponents are to be investigated. RMA is given by the geometric mean of the two OLS slopes obtained by interchanging the dependent and independent variable. We discuss the potential of the Urban Kaya Relation in mainstreaming local actions for climate change mitigation.},
  language  = {en}
}
@article{ZhouRybskiKropp2017,
  author    = {Zhou, Bin and Rybski, Diego and Kropp, J{\"u}rgen},
  title     = {The role of city size and urban form in the surface urban heat island},
  series = {Scientific reports},
  volume    = {7},
  journal   = {Scientific reports},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-017-04242-2},
  pages     = {9},
  year      = {2017},
  abstract  = {Urban climate is determined by a variety of factors, whose knowledge can help to attenuate heat stress in the context of ongoing urbanization and climate change. We study the influence of city size and urban form on the Urban Heat Island (UHI) phenomenon in Europe and find a complex interplay between UHI intensity and city size, fractality, and anisometry. Due to correlations among these urban factors, interactions in the multi-linear regression need to be taken into account. We find that among the largest 5,000 cities, the UHI intensity increases with the logarithm of the city size and with the fractal dimension, but decreases with the logarithm of the anisometry. Typically, the size has the strongest influence, followed by the compactness, and the smallest is the influence of the degree to which the cities stretch. Accordingly, from the point of view of UHI alleviation, small, disperse, and stretched cities are preferable. However, such recommendations need to be balanced against e.g. positive agglomeration effects of large cities. Therefore, trade-offs must be made regarding local and global aims.},
  language  = {en}
}
@article{ZhouLauwaetHooyberghsetal.2016,
  author    = {Zhou, Bin and Lauwaet, Dirk and Hooyberghs, Hans and De Ridder, Koen and Kropp, J{\"u}rgen and Rybski, Diego},
  title     = {Assessing Seasonality in the Surface Urban Heat Island of London},
  series = {Journal of applied meteorology and climatology},
  volume    = {55},
  journal   = {Journal of applied meteorology and climatology},
  publisher = {American Meteorological Soc.},
  address   = {Boston},
  issn      = {1558-8424},
  doi       = {10.1175/JAMC-D-15-0041.1},
  pages     = {493 -- 505},
  year      = {2016},
  abstract  = {This paper assesses the seasonality of the urban heat island (UHI) effect in the Greater London area (United Kingdom). Combining satellite-based observations and urban boundary layer climate modeling with the UrbClim model, the authors are able to address the seasonality of UHI intensity, on the basis of both land surface temperature (LST) and 2-m air temperature, for four individual times of the day (0130, 1030, 1330, and 2230 local time) and the daily means derived from them. An objective of this paper is to investigate whether the UHI intensities that are based on both quantities exhibit a similar hysteresis-like trajectory that is observed for LST when plotting the UHI intensity against the background temperature. The results show that the UrbClim model can satisfactorily reproduce both the observed urban rural LSTs and 2-m air temperatures as well as their differences and the hysteresis in the surface UHI. The hysteresis-like seasonality is largely absent in both the observed and modeled 2-m air temperatures, however. A sensitivity simulation of the UHI intensity to incoming solar radiation suggests that the hysteresis of the LST can mainly be attributed to the seasonal variation in incoming solar radiation.},
  language  = {en}
}
@article{FluschnikKriewaldRosetal.2016,
  author    = {Fluschnik, Till and Kriewald, Steffen and Ros, Anselmo Garcia Cantu and Zhou, Bin and Reusser, Dominik Edwin and Kropp, J{\"u}rgen and Rybski, Diego},
  title     = {The Size Distribution, Scaling Properties and Spatial Organization of Urban Clusters: A Global and Regional Percolation Perspective},
  series = {ISPRS International Journal of Geo-Information},
  volume    = {5},
  journal   = {ISPRS International Journal of Geo-Information},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2220-9964},
  doi       = {10.3390/ijgi5070110},
  pages     = {1543 -- 1559},
  year      = {2016},
  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 \&\#948; \&\#8776; 0.85, i.e., large cities have lower densities.},
  language  = {en}
}
@article{ZhouRybskiKropp2013,
  author    = {Zhou, Bin and Rybski, Diego and Kropp, J{\"u}rgen},
  title     = {On the statistics of urban heat island intensity},
  series = {Geophysical research letters},
  volume    = {40},
  journal   = {Geophysical research letters},
  number    = {20},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {0094-8276},
  doi       = {10.1002/2013GL057320},
  pages     = {5486 -- 5491},
  year      = {2013},
  abstract  = {We perform a systematic study of all cities in Europe to assess the Urban Heat Island (UHI) intensity by means of remotely sensed land surface temperature data. Defining cities as spatial clusters of urban land cover, we investigate the relationships of the UHI intensity, with the cluster size and the temperature of the surroundings. Our results show that in Europe, the UHI intensity in summer has a strong correlation with the cluster size, which can be well fitted by an empirical sigmoid model. Furthermore, we find a novel seasonality of the UHI intensity for individual clusters in the form of hysteresis-like curves. We characterize the shape and identify apparent regional patterns.},
  language  = {en}
}