Abstract: Heat wave event accompanying with global warming has a great influence on the social economy and human health. Baotou City, the largest industrial city in the Inner Mongolia Autonomous Region of northern China, was selected as the study area. Land surface temperature of Baotou City was retrieved by the method of single-window algorithm using 8 periods remote sensing images from the Landsat 5 TM taken in 2001 to 2011 and 2 periods Landsat 8 OLI in 2013 and 2014. Then, the spatial distribution of ground temperature(2 m height from the ground)in Baotou City in recent 14 years was analyzed by building the relationship between land surface temperature and daily maximum air temperature recorded at weather station. Finally, with the population data of Baotou from 2001 to 2014, population exposure risk to high temperature was evaluated in the four districts in Baotou City, which were Kundulun District, Qingshan District, Donghe District and Jiuyuan District. The results show as follows:(1)during the recent 14 years, heat waves in Baotou appeared in 2001, 2005, 2010 and 2011, especially in 2010, the heat waves had appeared for 8 consecutive days with high temperature(40.1 ℃); the highest air temperature reached 40.4 ℃ in 2005, while the temperature was relative low in 2003, 2004 and 2009, the lowest temperature was 33.3 ℃ in 2003. The high temperature zones were distributed in the industrial, residential and commercial zones; whereas the temperature in areas of forest, farmland, garden, green space of park and square, water was relatively low.(2)According to the risk assessment for population exposure to high temperature, the area of low and medium risk zone increased, and the area of low risk zone reached the highest in 2008; the area of high risk zone gradually turned into medium risk zones with the change of urban green area; the area of extremely high risk zone was the least and appeared only in 2002 and 2004. The extremely high and high risk zones were distributed in Donghe District; the medium risk zones were mainly distributed in residential and commercial zones of Kundulun and Qingshan District; the low risk zones were distributed in industrial zones and the relatively less population area of Qingshan, Kundulun and Jiuyuan District, no risk zones were distributed in urban green space and water area. This research not only has innovation in theory and method, but also has great practical significance. However, two points are expected to be improved:(1)the selected remote sensing images were not in the same month(from June to August), and the correlation coefficient between land surface temperature from images and air temperature recorded at weather station was only 0.65, it can influence the spatial distribution of high temperature heat waves to some extent; (2)in the process of the risk assessment for population exposure to high temperature, the result was influenced by some factors, including less detailed demographic data of communities, and the subjective weight of population distribution based on urban land use.

Key words: heat wave, population exposure, risk assessment, recent 14 years, Baotou City