Liu X., Derudder B. and Wu K. Measuring polycentric urban development in China: an intercity transportation network perspective, Regional Studies. This paper measures polycentric development in 22 urban regions in China by analysing intercity transportation networks. A typology of Chinese urban regions is identified based on individual regions’ functionally and morphologically polycentricity. Three major sets of processes underlying the typology are discerned: the (mis)match between (governmentally) designated and economically integrated urban regions; unequal interregional economic development; and the impact of city-regional plans and policies. Urban regions along the east coast reach high levels of morphological and functional polycentricity. Many planned urban regions are morphologically polycentric, lacking functional integration. Most urban regions in western China lack any form of polycentricity.

The brightness of pixels in nighttime light images (NTL) has been regarded as the proxy of the urban dynamics. However, the great difference between the pixel values of NTL from the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) and the Suomi National Polar-orbiting Partnership satellite’s Visible Infrared Imaging Radiometer Suite (Suomi NPP/VIIRS) poses obstacles to analyze economic and social development with NTL in a continuous temporal sequence. This research proposes a methodology to align the pixel values of both NTL by calibrating annual DMSP images between the years 1992–2013 with a robust regression algorithm with a quadratic polynomial regression model and simulating annual DMSP images with VIIRS images between years 2012 and 2018 with a model consisting of a power function and a Gaussian low pass filter. As a result, DMSP annual images between years 1992–2018 can be produced. Case study of Beijing and Yiwu are conducted and evaluated with local gross domestic product (GDP). Compared with the values of DMSP and VIIRS annual composites, the Pearson correlation coefficients of DMSP and simulated DMSP annual composites in 2012 and in 2013 increase significantly, while the root mean square error (RMSE) decrease evidently. In addition, the correlation of the sum of light of NTL and local GDP is enhanced with a simulation process. These results demonstrate the feasibility of the proposed method in narrowing the gap between DMSP and VIIRS NTL in pixel values.

Fine-particulate pollution is a major public health concern in China. Accurate assessment of the population exposed to PM_2.5 requires high-resolution pollution and population information. This paper assesses China’s potential population exposure to PM_2.5, maps its spatiotemporal variability, and simulates the effects of the recent air pollution control policy. We relate satellite-based Aerosol Optical Depth (AOD) retrievals to ground-based PM_2.5 observations. We employ block cokriging (BCK) to improve the spatial interpolation of PM_2.5 distribution. We use the subdistrict level population data to estimate and map the potential population exposure to PM_2.5 pollution in China at the subdistrict level, the smallest administrative unit with public demographic information. During 8 April 2013 and 7 April 2014, China’s population-weighted annual average PM_2.5 concentration was nearly 7 times the annual average level suggested by the World Health Organization (WHO). About 1322 million people, or 98.6% of the total population, were exposed to PM_2.5 at levels above WHO’s daily guideline for longer than half a year. If China can achieve its Action Plan on Prevention and Control of Air Pollution targets by 2017, the population exposed to PM_2.5 above China’s daily standard for longer than half a year will be reduced by 85%.