Characteristics Of Sea-land Breeze In Different Coastal Zones Of Shanghai And Their Influence On The Spatial And Temporal Distribution Of Ozone

With the rapid development of social economy and urbanization,the air pollution problem has changed from a single type to a complex type,which has aroused widespread concern.PM2.5 and ozone are the main pollutants of composite air pollution in Shanghai,and ozone pollution is becoming more and more prominent.Sea-land breeze is a weather phenomenon caused by the difference of sea-land thermal properties,which plays an important role in the transport of atmospheric pollutants in coastal cities.In this paper,The data product OMO3 PR of OMI was used to analyze the ozone of Shanghai and its adjacent sea areas from 2010 to 2019,and the spatial and temporal distribution characteristics of ozone concentration in this region were studied.ERA5 reanalysis data were used to study the characteristics of sea-land breeze in different coastal zones of Shanghai,taking Jinshan Station and Pudong Station as examples.Combined with the ozone concentration data of ground monitoring stations in Shanghai,the influences of different types of sea-land breeze on the spatial and temporal distribution of ozone concentration are analyzed.The main conclusions are as follows:（1）The sea-land breeze at Jinshan station and Pudong station have different seasonal daily variation characteristics.Pudong station has the most sea-land breeze days in summer,while Jinshan station has more sea-land breeze days in winter and spring,less sea-land breeze days in summer and autumn,the number of large-scale sea-land breeze days is smallest.At Jinshan station,the wind direction of land breeze and sea breeze is mostly at the mouth of Hangzhou Bay when there is local land breeze,while it is closer to the direction perpendicular to the coastline when there is a largescale sea-lane breeze.The dominant breeze direction of sea breeze and land breeze at Pudong station is SSE and SSW,respectively.The dominant wind direction of land breeze is NNW and N,and the sea breeze is SSE and SE when the local sea-land breeze occurs.（2）The diurnal variation trend of boundary layer height at Jinshan station is stronger,while the seasonal characteristics of boundary layer height at Pudong Station are more obvious.The frequency of ground inversion at jinshan station is low in spring and summer,and relatively high in autumn and winter both in the two kinds of sea-land breeze days.The inversion frequency of pudong station is higher in spring,summer and winter of local sea-land breeze days,while the inversion frequency of four seasons is close to that of large-scale sea-land breeze days.（3）The variation trend of ozone concentration in the three regions is similar.The highest ozone concentration in the lower troposphere is in summer,followed by spring,autumn and winter.In region A from 2010 to 2019,the maximum monthly mean of ozone concentration in the lower troposphere appeared in June and July,and the minimum in December or January.Except at 500 h Pa-300 h Pa,the monthly mean ozone concentration at other tropospheric heights showed significant periodic variation.（4）In summer,the ozone level exceeds the standard when there is a sea-land breeze is significantly higher than when there is no sea-land breeze,and the local sea-land breeze in Pudong is the biggest.The peak time of ozone concentration in sea-land breeze days is generally similar or slightly later than that without sea-land breeze.The ozone concentration near the surface of Jinshan station is low in the south coastal zone of Shanghai when the Jinshan local sea-land breeze day.Pudong station is located in the area of high ozone concentration in the northeast coast of the local sea-land breeze days.In the large-scale sea-land breeze days,ozone concentration in Pudong Station is at medium level,while Jinshan Station is in a high ozone concentration area.When no sea-land breeze occurs,the ozone concentration in the whole region is relatively close when there is no sealand breeze.