Study on the Temporal and Spatial Variation of PM 2.5 in Eight Main Cities of Yunnan Province

Air haze pollution has a serious impact on human health, ecological environment and climate change. In recent years, with the introduction of new national policies and people's increasing awareness of environmental protection, haze has received widespread social attention. Haze pollution in China has always been a prominent environmental problem. The main reason for the frequent occurrence of haze pollution is PM2.5, which not only occurs in cities with high degree of industrialization or urbanization, but also often appear in regions with good air quality. This paper selects eight main cities in Yunnan Province as the research area, and uses the measured PM 2.5 data from eight main cities in January 2015 to February 2018 in Yunnan Province as the basic data, using the eight urban meteorological data as the basic data, using the MK trend test and Correlation coefficient method to carry out research on the spatial-temporal variation and correlation of PM 2.5 in the last three years in Yunnan Province. The space-time analysis shows that the average annual PM 2.5 concentration in Lijiang City is the lowest, the monthly average concentration in Baoshan City is the highest, and the daily average concentration in Puer City is in a gentle trend; Except for Lijiang, the other seven cities all experienced different levels of pollution from March 17 to March 26, 2015; The concentration of PM 2.5 in each city showed a seasonal pattern of “U” and a pulse-like diurnal variation pattern in winter and spring, summer and autumn; cities with higher annual average concentrations in the province are concentrated in the northeast and southwest. Correlation analysis showed that PM 2.5 concentration was significantly negatively correlated with precipitation and wind speed, and negatively correlated with daily average humidity and temperature.