Spatial And Temporal Distribution Of Urban-rural Differences Of PM_2.5 In Zhengzhou During Cold Season

In recent years,Zhengzhou’s urbanization process has continued to accelerate.Although the government has formulated more stringent requirements,PM2.5 pollution in Zhengzhou is still more severe.In the most severe PM2.5 pollution in the winter,Zhengzhou has not yet for the rural and urban PM2.5 Spatio-temporal distribution characteristics of the study,so the study of the spatial and temporal distribution of PM2.5 during the winter prevention period of Zhengzhou City and the correlation between urban and rural PM2.5 and meteorological factors are critical.This paper divides Zhengzhou’s urban and rural areas by night light data,normalized vegetation index data and elevation data.Based on a variety of reanalysis datasets and wind speed and wind direction data of meteorological monitoring stations,the spatial autocorrelation analysis of PM2.5 during the winter prevention period in Zhengzhou was carried out,and the correlation analysis of PM2.5 concentration and meteorological elements during the winter defense period was analyzed,and the temporal variation law of PM2.5 and meteorological elements in urban and rural areas was studied from three scales:daily average change,hourly change and pollution process change.The results show that there is a high-high concentration of PM2.5 in the temporal and spatial distribution of PM2.5 in Zhengzhou during the winter prevention period,and the low-value areas of PM2.5 concentration in the winter prevention period of Zhengzhou city from 2016 to 2020 are basically located in the coverage area of the Songshan Mountains,but the distribution of the high PM2.5 concentration areas is different in each year,of which the PM2.5 concentration in urban areas in 2016,2017 and 2018 is greater than that in rural areas,and the PM2.5 concentration in rural areas in 2019 and 2020 is greater than that in urban areas.The relative humidity during the winter prevention period in 2019 was positively correlated with the PM2.5 concentration in all urban and rural areas,the temperature was also positively correlated with the PM2.5 concentration in urban and rural areas,the wind speed was negatively correlated with the PM2.5 concentration in urban and rural areas,and the boundary layer height was also negatively correlated with the PM2.5 concentration in urban and rural areas.The most obvious is that for the southern countryside and the western countryside,only the correlation between temperature and PM2.5 concentration passed the significance test,indicating that the temperature in these two regions has the greatest impact,and for urban areas,northern villages and eastern villages,in addition to temperature,other meteorological factors and PM2.5 concentrations are significantly correlated,of which relative humidity has the strongest correlation with PM2.5 concentration,indicating that the greatest impact on humidity in these three regions.In the winter prevention period of 2019,the overall PM2.5 concentration level was the lowest in November,and the overall PM2.5 concentration level in January was the highest,and the distribution pattern of temperature and humidity was basically the same.The spatial distribution is characterized by higher concentrations of PM2.5 in regions with higher temperatures and humidity.Wind speeds were negatively correlated with PM2.5 concentrations in all urban and rural areas,but the correlation between wind speeds and PM2.5 concentrations in rural southern and western rural areas was not significant.When the overall PM2.5 concentration is higher in the urban and rural areas,the probability of PM2.5 concentration decline is larger,according to the region may be southwest wind,positive west wind or northwest wind,when the east wind appears,PM2.5 pollution will be more serious,in November,the overall PM2.5 concentration is lower,the emergence of westerly wind may also aggravate the local pollution level,static wind breeze conditions will make PM2.5 pollution in urban and rural areasThe daily variation characteristics show that abnormal temperature reduction and the increase will adversely affect the stability of PM2.5 concentration in urban and rural areas,and the change of humidity means and the change of PM2.5 concentration show apparent consistency.The PM2.5 concentration also increases when the humidity rises,and the PM2.5 concentration also decreases when the humidity decreases.Hour-by-hour data correlation analysis shows that PM2.5 temperature and wind speed are negatively correlated and positively correlated with humidity.The hourly change characteristics show that PM2.5 and temperature humidity in urban and rural areas show typical "single peak and single valley" characteristics,and the peak of urban areas occurs at the earliest time,and the overall nighttime concentration is higher than that during the day.The characteristics of daily change,hour change,and pollution process change together reflect a certain lag in the response of PM2.5 concentration to temperature and humidity changes.