Analysis Of The Spatiotemporal Distribution Characteristics Of Air Quality In Hubei Province And Its Influencing Factors From 2015 To 2019

Based on the air quality data of observed cocentrations in 13 cities in Hubei Province from 2015 to 2019,the meteorological data in key cities,and the assimilated meteorological fields from the global data assimilation system,this work examined the temporal and spatial distributions,the influencing factors and transmission characteristics of air pollutants in Hubei Province.The results show that:1.From 2015 to 2019,the overall air quality in Hubei Province showed a trend of improvement.2018 was the best year in the 5 years,and there was a slight rebound in 2019.For various pollutants,the annual average concentrations of PM_2.5,PM₁₀,NO₂,SO₂ and CO showed a decreasing trend from 2015 to 2019,while the annual average concentration of O₃ showed a significant increasing trend.Generally,in Hubei Province,air quality in the western region was better than that in the eastern and central regions.PM_2.5 concentrations were the highest in the central region and the second highest in the eastern region,whereas the lowest in western region.With respect to O₃,concentrations were highest in the eastern region,followed by the central region,and the western region.2.Precipitation,temperature,relative humidity,sunshine duration,wind direction and wind speed exhibited high correlations with air quality.Precipitation had a scavenging effect on air pollutants,but the effects were different under different levels of precipitation.Under the condition of low humidity,the effect of wet growth was obvious,and under the condition of high humidity,the effect of cleaning was obvious.High temperatures would lead to more active reactions in the atmosphere,leading to a significant increases in O₃ concentrations.The sunshine duration had a high correlation with photochemical reactions and a significant positive correlation with O₃concentration.Wind direction and wind speed had different effects.3.The results of the backward trajectory analysis showed that,in the past five years,the air masses that caused high concentrations of PM_2.5 in Hubei mainly came from the northwest or the west as a result of long-distance transportation,while the air masses that caused high concentrations of O₃ mainly came from the east or the northeast.In addition,on the basis of the concentration-weighted analysis,the major area of PM_2.5 concentration weight was shrinking year by year,while the area of O₃concentration weight was increasing year by year.The analysis of heavy pollution cases found that there were two obvious transmission channels in the PM_2.5 pollution process in Hubei,both of which originated from Xiangyang.There were no obvious transmission channels in the O₃ pollution process,and O₃ concentrations in each city increased simultaneously.