Analysis of day-night characteristics of urban heat island effects in Chengdu based on NOAA/AVHRR in winter

In this paper, NOAA/AVHRR data were used, which were obtained in winter of 2004 and 2006 respectively. And using NOAA/AVHRR data in spring of 2004 as reference, day-night characteristics and spatial distribution characteristics were received. The following are research results. In the daytime, urban heat island intensity was stronger than that at night. The maximum of urban heat island intensity was about 7.5deg and 9.0deg respectively.At night, urban heat island demonstrated a single-center or double-centers, and urban heat island center lied within the second circuit road. In the daytime, urban heat island demonstrated multi-centers. Urban heat island centers occurred in industrial and commercial districts, in transport hub, which locate in the north, the east, or the southwest of the city. Little higher temperature zone distributed like a non-closed ring. High temperature ring occurred nearby the second and third circuit road. The ring characteristic of urban heat island had close relationship with urban structure and urban activities, which was consist with some research results in summer.