Regional thermal environments (RTEs) and driving forces in six urban agglomerations of China and America

China and America have several large urban agglomerations that are important for global urbanisation, but both face serious regional thermal environment (RTE) problems. This study compares the RTE of six urban agglomerations in China and America in summer in terms of the thermal landscape and surface urban heat island intensity (SUHII) distributions using Terra MODIS land surface temperature (LST) data and analyses the impacts of land development intensity (LDI), the normalised difference vegetation index (NDVI), precipitation, wind speed, and surface albedo on the RTE. The results show that the RTE problem of aggregated high or sub-high LST zones in large areas across city boundaries is widespread in Chinese urban agglomerations. However, the RTE problem of high SUHII values is more obvious in American urban agglomerations. The LDI and LST have a strong spatial correlation that shows a clear upward trend in Chinese urban agglomerations. The oLDI and oNDVI have significant impacts on the SUHII of urban agglomerations in China and America. The impacts of precipitation, wind speed, and albedo on the SUHII vary greatly between China and America. By further examining the spatial structure of the LDI, gross domestic product (GDP), and population in urban agglomerations, this study suggests that constructing a decentralised, multicentre network spatial structure in urban agglomerations, improving urban vegetation coverage and ventilation, and selecting appropriate building materials may be important paths to improving the RTE and promoting the sustainable development of urban agglomerations.