Antarctic Surface Ozone Background Characteristic And Its Influence Factors

As significant atmospheric oxidant, greenhouse gas, and pollutant, surface ozone is closely related with climate change and environmental problem. Antarctica,considered as global atmospheric background with little anthropogenic activity, is an ideal region of atmospheric composition monitoring. During the 4th International Polar Year (2007/2008),atmospheric background monitoring site with continous atmosphere observation was established at Zhongshan Station. Based on surface ozone continous data, meteorological data and other related data, background characteristic of surface ozone concentration during 2008-2013 at Zhongshan Station is presented and discussed. Meanwhile,there are comparisons of surface ozone data between Zhongshan Station and other Antarctic and global stations, and analyzations on Ozone Depletion Episode (ODE) during springtime at Zhongshan Station. There are some results as follow:Under different wind direction and speed condition, surface ozone concentration at Zhongshan Station change little, which shows surface ozone concentration at Zhongshan Station is affected little by local polluted emission and can represent background concentration of surface ozone on the east coast of the Antarctica.Significant seasonal variation of surface ozone concentration is observed at Zhongshan station. Monthly average maximum value appears in winter (Jul. and Aug)and the minimum in summer (Dec. and Jan.). The monthly average concentration ranges from 15 to 35 ppb.There is a strong negative correlation between surface ozone concentration and ultraviolet radiation in spring and autumn and surface ozone concentration during polar night is 1?2 times higher than during polar day, which indicates photo-chemistry destruction on surface ozone is dominated in Antarctic. With little anthropogenic influence,Antarctic is a ideal region to analysis global surface ozone variation.Seasonal variation of surface ozone at Zhongshan Station is similar to other Antarctic coastal sites with maximum in winter and minimum in summer and concentration ranges between 15-35 ppb. Yearly variation is only 1-2 ppb at Antarctic sites, and spatial variation of yearly averge concentration is 2 ppb at coastal sites.Comparation between global sites in different regions shows surface ozone concentration in northern hemisphere sites is higher than south hemisphere, and significant seasonal variation of surface ozone is observed in southern sites. Surface ozone concentration in northern hemisphere sites change with latitudes while ozone level in southern hemisphere sites are closer, which is related more human activities in northern hemisphere.Ozone data at Antarctic sites appear ODEs with surface ozone concentration rapid decreasing and recovery later during spring in Antarctic coast regionODEs are frequently occurred in spring at Zhongshan Station. During ODEs,weather process has suddenly change, at the same time air temperature dropping,northerly wind with lower speed increasing from sea ice area. Happening of ODE is mainly related with reactive bromine (BrO) concentration of sea ice area. In spring,open leads and polynyas are formed by the freezing and thawing process of sea ice,then young ice and frost flower is produced by cool air onset on Antarctic coast.Satellite has monitored high concentration active bromine derived from sea salt released in young ice area, and reactive bromine reacts with ozone to account for ODE. The phenomenon is under natural condition without anthropogenic pollution,which is different from ozone depletion by photochemical reaction in mid-high latitudes.