Simulation of the urban climate in a Chinese megacity with spatially heterogeneous anthropogenic heat data

Anthropogenic heat release (AHR) by human activities in cities is a key contributing factor to the generation of the urban heat island (UHI) effect; thus, AHR should be incorporated into urban climate and environmental modeling. In this study, gridded AHR data with high spatial resolution (1 km) were included in the integrated weather research and forecasting (WRF)/urban modeling system to investigate the urban environment of Hangzhou City, which is the capital of Zhejiang Province in east China. The AHR data were estimated for this province based on the significant correlation between energy consumption statistics data and multisensor remote-sensing data (namely, nighttime light imagery and a vegetation index). The coupled model was evaluated against available observational data derived from a dense automatic weather station network in Hangzhou. The effects of AHR and urban land use on the urban environment were investigated with three sensitivity numerical experiments. Results showed that the mean UHI intensity reached 0.95 degrees C and 1.66 degrees C in winter and in summer, respectively, and that AHR contributed 65.26% and 17.47% to UHI intensity in the two seasons. In winter, AHR significantly impacted the diurnal variation in UHI, and the two UHI intensity peaks ascribed to AHR were detected during rush hours. The impact of AHR on planetary boundary layer (PBL) height was similar to its contribution to UHI effect, with a large contribution in winter. Moreover, UHI enhanced atmospheric vertical motions, which led to precipitation changes, especially during summer. A convective and deep PBL was detected and triggered convective precipitation over or downwind of Hangzhou City during summer. Given the anticipated increase in global urban populations, characterizing the spatial-temporal variations of AHR and its impacts is essential toward continued progress in urban climate assessment.