About 56% of the world's population now lives in urban areas and this percentage will continue to increase in the coming decades. Urban environment and sustainability is thus of great importance. Our research focuses on a range of major environmental issues in urban areas, covering: (1) air pollution and its interactions with climate, as well as public health impacts, (2) urban climatology, (3) urban hydrology and water management, (4) urban ecology and biogeochemistry, and (5) urban environmental assessment and management. In our research, we use a variety of methods and tools, including statistical and dynamic modeling, monitoring and measurement (both in-situ and remote sensing), and GIS. Our track records have demonstrated our strength in urban environmental research and we will continue to advance knowledge of the physical and chemical processes of the urban environmental system, in particular the evolution of urban environmental problems at various spatio-temporal scales and their induced impacts. Our research strives not only to better understand urban environmental system, but also to provide scientific support for enhancing urban environmental quality and sustainability.