Spatiotemporal Distribution Characteristics And Relationship Analysis Of Beijing-Tianjin-Hebei PM_2.5 Concentration And Urban Heat Island Effect

With the rapid economic growth and development of urbanization in China,air pollution has become one of the serious environmental problems.Urban air pollutants mainly come from the burning of fossil fuels in factories and vehicles.Daily human behavior in cities also releases a large number of polluting particles into the urban atmosphere.With the in-depth development of air pollution control,the problem of composite air pollution represented by PM_2.5has become increasingly prominent,which has severely affected the ambient air quality and the health of people.Urban heat island is the most prominent urban climate problem in the process of urbanization.The impact of urban heat islands not only affects the local climate,but also affects the residents'production and life to varying degrees,endangering human health.In recent years,the relationship between urban heat islands and atmospheric pollutants has become one of the hot spot of research.It is significance to explore the impact of urban heat islands and PM_2.5concentrations on improving the urban environment and the quality of life of residents.This article uses pollutants data,MOD04?3K aerosol data and MOD11A2 surface temperature data.This article studies spatial-temporal distribution characteristics of PM_2.5concentration and urban heat islands in Beijing-Tianjin-Hebei region from 2014 to2018.Expored the correlation relationship between the urban heat islands and PM_2.5concentrations in Beijing-Tianjin-Hebei area through a coupled coordination model and correlation analysis methods.Conclusion as below:(1)Spatially,the spatial distribution of PM_2.5in each season in the Beijing-Tianjin-Hebei region basically shows a trend of"high in the south and low in the north".The central plain and Cangzhou coastal plain belong to long-term high-polluted areas.The northern Hebei mountainous area is the lowest concentration areas.In terms of time,the season with the heavy PM_2.5pollution is winter,the PM_2.5concentration is the lowest in summer,the PM_2.5pollutant levels are similar in spring and autumn.The concentration of PM_2.5in the 13 major cities in Beijing,Tianjin,and Hebei has decreased significantly in winter from 2014-2018.(2)The centers of urban heat islands are mainly distributed in the 13 major urban areas of Beijing,Tianjin,and Hebei.The heat islands are concentrated in the Cangzhou coastal plains in spring and summer.In the autumn and winter,the hot island area moves south to the Xingtai and Handan areas in the southeast of Beijing,Tianjin,and Hebei.From 2014 to 2018,the heat island area expanded during the day and night.The heat island area was connected by points along the traffic line to form a point-line structure,and then expanded to the surrounding area.(3)Under the background of urban heat island,there is a positive coupling relationship between the surface temperature and PM_2.5concentration in the Beijing-Tianjin-Hebei region in spatial distribution.The spatial distribution of heat islands and PM_2.5concentrations during the day and night in each season showed a trend of"high in the south and low in the north".Under the test condition of significance level 0.01,the urban heat island in summer had the least significant correlation with PM_2.5mass concentration,followed by autumn,and most in spring and winter.Among the 13 major cities in Beijing,Tianjin and Hebei,the strong heat island in spring had a significant negative correlation with PM_2.5concentration,and the weak heat island in winter had a significant positive correlation with PM_2.5concentration.From different cities,the Zhangjiakou heat island effect was related to PM_2.5concentration.significantly positive correlation.Beijing and Tianjin urban heat islands showed a positive correlation with PM_2.5concentrations.