【作者】 史晋森；

【导师】 张武；

【作者基本信息】 兰州大学 ， 大气物理学与大气环境， 2008， 硕士

【摘要】 O₃是大气中极其重要的温室气体,对紫外辐射UV-AB波段具有很强的吸收作用,同时O₃又具有很强的氧化性,参与大气中大部分化学和光化学反应。在全球变暖的大背景下O₃对气候与环境的影响已经是人类关注的一个焦点。本文首次利用半干旱地区一个观测站点（SACOL）将近一年的O₃观测资料,以及相关的其它资料对地面O₃变化特征及影响因素进行分析研究,对该地区的近地面O₃浓度进行模拟计算,以期系统地了解半干旱地区O₃的基本特征。主要研究结果如下:在不同的天气情况之下,地面O₃浓度的日变化特征是:晴天、多云和沙尘天气的日变化曲线只有一个较大峰值区出现,而阴天、雨天和雪天的日变化曲线会有多个较大的峰值区域出现。在晴天O₃浓度变化幅度最大,平均值也是最大,其次依次是多云天、阴天、降水天。O₃浓度的季节变化是白天平均O₃浓度在夏季最大,然后依次是秋季、春季、冬季;夜间最大浓度也出现在夏季,春季次之,最小的是冬季。SACOL站的全年O₃浓度观测值均达到国家规定的一级环境质量标准。在影响臭氧的气象要素中,温度与地面O₃浓度之间日变化趋势相近,臭氧峰（谷）值比温度峰（谷）值出现的时间大约早（晚）1-2小时:降水对O₃具有湿清除作用;冷锋过境会引起O₃浓度的降低。O₃与前体物NO、NO₂和CO之间的浓度呈负相关变化,日变化趋势相反。O₃浓度升高有利于NO、NO₂转化为其他形式的氮氧化物,导致NO、NO₂的下降。O₃浓度与NO₂/NO的比值之间也有很强的对应关系,NO₂/NO值的增大对应O₃浓度的减小。地面O₃浓度和紫外辐射的年变化趋势相似,两者同在一年中的6-8月份达到最大值,最小值在11月到1月期间。在白天,地面紫外辐射强度晴天的要明显高于多云天和阴天,多云天的又要高于阴天,对应的O₃浓度也有相似的特征。O₃浓度的日变化峰（谷）值要迟于紫外辐射UV-AB峰（谷）值出现的时间。分析了影响O₃浓度的主要因子,其包括太阳辐射、化学和光化学过程和气溶胶。根据紫外辐射能量转化和守恒定律建立计算地面臭氧浓度的模型,并利用SACOL站2007年8-10三个月的相关资料进行逐步回归分析,得出计算地面O₃浓度的回归方程。在晴天和实际天气状况下得到模式计算结果的相关性R都在0.9以上,光化学项、NO₂项、紫外辐射项、气溶胶项对O₃项都有显著性影响。而在阴雨天气紫外辐射项对O₃的变化没有显著性影响,R值为0.881。在晴天的情况下影响O₃项的因素排序依次是光化学项、NO₂项、紫外辐射项、气溶胶项;在实际天气下依次是光化学项、气溶胶项、紫外辐射项、NO₂项;在阴雨天气依次是光化学项、气溶胶项、NO₂项。更多还原

【Abstract】 Ozone is a very important greenhouse gas in the atmosphere,and can absorb UV very strongly.The oxidative of ozone is very strong,so it can participate in the most chemical and photochemical reactions.People have focused more attention on the influence of ozone to climate and environment on the background of global warming. In this paper,the observation data of ozone about one year and some other kinds of correlative data in SACOL are used to analyze the variation characteristics of ozone for the first time.The factors that influence ozone concentration variation are also analyzed for the first time.The ozone concentration over surface in this area is estimated and simulated,in order to know the basal characteristic of ozone in semi-arid area in detail.The main research outcomes are as follows:Under the different backgrounds of weather,the diurnal variation characteristic of ozone concentration over surface is that:there is only one peak value in clear sky, cloudy and dusty days,while there are several peak values in the overcast,rainy and snowy days.The variation range of ozone concentration is the largest in clear sky days,and the average is also the largest,followed by cloudy,overcast,precipitation.The seasonal variation of ozone concentration is that the average ozone concentration in daytimes is the largest in summer,and then followed by autumn, spring and winter;the average concentration during nights is also the largest in summer,and then followed by spring,autumn and winter.The ozone concentration in SACOL can reach first class national environmental quality standard in the whole year.There are very strong corresponding relations between ozone concentration and surface temperature;the peak（valley）value of ozone concentration is about 1-2 hours earlier（later）than the peak（valley）value of temperature.The change trend of ozone and temperature is similar.Precipitation plays a very important role in wet removal of ozone.Ozone concentration can be reduced down when the cold front pass through this area. There is a negative correlationship between ozone and its precursor such as NO, NO₂ and CO,and its trend of daily variation contrary to them.The increasing of ozone concentration is advantageous to that NO and NO₂ convert to other forms of nitrogen oxide,and could cause decreasing of NO and NO₂ concentration.There is a significant correlationship between ozone concentration and NO₂/NO,and the ozone concentration is decreasing while NO₂/NO increasing.There is a similar annual variation trend between surface ozone concentration and ultraviolet radiation,and both of their values reach to the maximum from June to August of a year,and the minimum values appear between November and January.In daytime,the ground ultraviolet radiation in clear sky days is much higher than that in cloudy and overcast days,and the value in cloudy day is higher than that in overcast day.Corresponding to the ultraviolet radiation,the ozone concentration has the same variation trend.The appearance time of peak（valley）value of diurnal variation of ozone concentration is later than the appearance time of peak（valley）value of UV-AB.The main factors that influence ozone concentration are analyzed,such as solar radiation,chemical and photochemical reactions,aerosol and so on.According to the law of energy conversion and conservation of ultraviolet radiation,a theoretical model for the surface ozone concentration simulation is established.Using the data observed in SACOL from August to October in 2007,the parameters of this model are estimated by stepwise regression analysis.The multi-correlation coefficients R in both cases are above 0.9 no matter in clear sky or the actual sky days.Photochemistry,NO₂ concentration,ultraviolet radiation and aerosol concentration all have significant effects on ozone concentration.In overcast and rainy days,ultraviolet radiation has little contribute to ozone concentration,and the R is 0.881.In clear sky days, photochemistry is the most important impact factor on the ozone concentration,and then followed by NO₂ concentration,ultraviolet radiation and aerosol concentration; in actual sky days,the order is photochemistry,aerosol,ultraviolet radiation and NO₂, and in rainy days,the order is photochemistry,aerosol and NO₂.更多还原