Analysis of Time Variation Characteristics of Ambient Air Quality in Lanzhou from 2015 to 2022
[Purposes]The temporal variation characteristics of ambient air quality in Lanzhou were ana-lyzed to provide a basis for air pollution forecasting and early warning and air pollution prevention and control in Lanzhou.[Methods]In order to study the ambient air quality of Lanzhou,this paper uses the hourly air quality data from January 1,2015 to December 31,2022 to statistically analyze the interannual,quarterly and daily characteristics of air quality and air quality grades from January 1,2015.[Findings]The results show that:① from 2015 to 2022,the number of good days is decreasing gradually,and the number of days with light and moderate pollution is decreasing;the air quality in Lanzhou is mainly ex-cellent,good and light pollution.② from January to December,the AQI index of Lanzhou was character-ized by"high in winter,spring and low in summer",and the number of good days increased first and then decreased.The number of days with light pollution and moderate pollution was inverted"U"type,the number of pollution days in December was the most,and the second peak appeared in March.③ the hourly AQI index in Lanzhou showed a typical bimodal feature,with daytime peak appearing at 9-12 and nighttime peak appearing at 20-23.[Conclusions]Based on the time change characteristics of environ-mental quality in Lanzhou,combined with the local weather and climate characteristics,it can provide a basis for air pollution forecast and early warning and air pollution prevention and control in Lanzhou.
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