Monitoring and assessing ghost cities in Northeast China from the view of nighttime light remote sensing data

Urbanization has proceeded at an unprecedented speed in China during the last 20 years, resulting in extensive natural landscapes being transformed into impervious surface. The ghost city phenomenon has emerged due to the unreasonable urban expansion which far exceeds the actual demand of human habitat. Previously, few research studies have provided objective and sufficient knowledge with regard to identify ghost cities and their spatial distribution. In this paper, we proposed an effective and feasible framework to monitor and evaluate ghost cities utilizing nighttime light imagery obtained from day-night band (DNB) of Visible Infrared Imaging Radiometer Suite (VIIRS). We established a ghost city index (GCI) to quantify the intensity of the phenomenon in the northeast of China, and analyzed the spatial pattern of ghost cities for different GCI classes. Our results indicate that the intensity of ghost city phenomenon decrease from regions adjacent to the border to interior areas, whilst regions with extremely high GCI are mostly districts and county cities. Tests of typical regions show that non-lit built-up area for high GCI regions is spatially clustered and low population regions have a high tendency to suffer from the ghost city phenomenon. Therefore, our findings provide a spatial-explicit insight into the ghost city phenomenon, and consequently can be beneficial to assist sustainable urban planning.