Analysis Of The Background Characteristics Of Atmosphereic Composition In Polar Regions

Global atmospheric concentrations of greenhouse gases, reactive gases and atmosphericaerosols are rising. They have become important factors affecting climate change. The polarregions are affected by minimal contamination, therefore, some countries including Chinastrengthen monitoring and research the background concentrations of greenhouse gas and soon in the polar regions. The atmospheric background monitoring station at the AntarcticZhongshan station was established during the fourth International Polar Year and somecontinuous data are observed. In this thesis, the background concentrations, seasonal cyclesand sources of black carbon （BC）, carbon dioxide （CO₂）, methane （CH₄） and carbonmonoxide （CO） are investigated by analysing the in-situ measurement, Flask sampling dataand meteorological data from2008to2010at the Zhongshan station. In addition, BC, aerosollight scattering coefficients （SC）, tropospheric ozone （O₃） and ultraviolet-B radiation （UVB）are investigated on a cruise ship during the fourth Chinese National Arctic ResearchExpedition from July1to September20,2010. The results of this paper are importantreference to improve the measurement level of polar greenhouse gas, to research thebackground characteristics of polar greenhouse gas and its climate effect. There are somepreliminary conclusions:Meteorological data of Zhongshan station show that winter is longer than summer. Themaximum and minimum of surface pressure at the Zhongshan station appear in April andOctober, respectively. Vapor pressures are small and little change in the whole year. Easterlywind （NE^ENE^EESE） is prevalent in the station area throughout the year. The averagewind speed is over7m·s^-1. The airflow affecting the station is most from the mainland coastand north sea.Under the influence of south to east-southeast air flow, BC concentrations are higher,because of the generation building and garbage incinerator emissions of the Zhongshanstation. When the wind speed is less than3m·s^-1, the BC concentration is high and unstable.The seasonal variation characteristics are that the minimum of BC concentration occurredduring the polar night （May to July）, and the maximum occurred in the spring and summer.The minimum is3.3ng·m^-3in May, and the maximum are10.0ng·m^-3and8.7ng·m^-3inFebruary and October, respectively, which are2³times of the minimum. This seasonal variation is similar to other stations in the Antarctic, but BC background concentration largerthan other Antarctic stations. It needs to be confirmed.CO₂is less affected by wind direction at Zhongshan station. The average concentrationunder the southeast wind （SE direction） is slightly larger. CO₂is larger in calm wind (windspeed≤0.5m·s^-1). There are obvious seasonal variations. The minimum concentrations appearin late summer, rising slowly in autumn and winter. And the maximum appear in spring. Thecause of this seasonal variation may be impacted by the seasonal variation of terrestrialecosystems and the Southern Ocean sea ice area and the seasonal adjustment of theatmospheric circulation. The consistent range and growth trends are between Flask data ofCO₂at Zhongshan and other Antarctic stations in the last three years. The CO₂values arebetween381³88ppm and the concentrations increase year by year. CO₂average annualgrowth rate is0.44%from2008to2010. It’s on behalf of the Antarctic CO₂growth trend.CH₄is less affected by wind direction and speed. The Flask sample data and in-situobservations are nearly the same. The peak of the year occurred in September, the monthlyaverage concentration is about1768.2ppb. It shows that there are obvious seasonal variations.The minimum concentrations appear in summer and autumn, maximum appear in spring.The average concentrations and growth rates of Zhongshan increase year by year from2008²010, which are slightly higher than the observations of the other Antarctic stations. Ingeneral, the CH₄at Zhongshan station is representative.The average CO concentrations under different wind directions are little difference.When calm wind or wind speed greater than21m·s^-1, the CO concentration is large. COconcentrations show obvious seasonal variation. The bottom occurred in January to Marchand the peak occurred in September and October. Compared with other Antarctic stations, theinterannual trend of Flask data at Zhongshan station is not obvious. The CO Flask data in2008and2009that can be comparable between Zhongshan station and other east Antarcticstations. But the values are low in2010. The reason may be that a problem of laboratorytesting, and it needs futher detection.BC, SC, O₃, and UVB decrease with increasing latitude, which are observed on thecruise ship during the fourth Chinese National Arctic Research Expedition. The maximumappear in the eastern waters of China, with minimum record in the Arctic Ocean. The averageBC is about10.5ng·m^-3in the Arctic Ocean. The average SC is4.3Mm-1and1.7Mm-1in theBering Sea and Arctic Ocean, respectively. The change of SC is stable in the north of76°N.The average O₃concentration in the Bering Sea is higher than that in the Arctic Ocean（15.7ppb）. However, O₃concentrations increase in the north of75oN area. It’s possible thatthis phenomenon is related to the sea ice density and photochemical processes. UVB has aclear diurnal cycle in the middle and low latitudes. Its amplitude is small with weak intensity in the Arctic Ocean due to the polar day effect during the cruise.