【作者】 毛晓琴；

【导师】 耿福海； 陈勇航；

【作者基本信息】 东华大学 ， 环境科学， 2010， 硕士

【摘要】 本文首先利用上海市气象局11个气象站地面观测资料对我国灰霾严重影响地区之一上海地区的灰霾气候特征和气象成因进行了分析,并利用地面气溶胶观测资料对灰霾发生时气溶胶物理特性进行了研究,然后利用地面微脉冲激光雷达资料反演了边界层高度,分析了不同强度灰霾发生时边界层高度的变化。最后采用国际上先进的CALIPSO卫星观测资料分析了长江三角洲地区灰霾的垂直分布特征。结果表明:上海地区多年平均的年灰霾日数约为154.6天。灰霾天气有明显的年变化,11月、12月、1月是灰霾天气的高发期。从季节变化来看,春季和冬季容易出现灰霾天气,轻度灰霾春季出现日数最多,重度灰霾冬季出现日数最多。风向、风速、降水量和降水天数与灰霾天气的发生都有密切关系。当上海吹西风、西南风和西北风时容易出现灰霾天气,而北风、东北风、东风、东南风对大气有一定的净化作用,灰霾天气出现较少。逆温层厚度和强度影响灰霾强度,从轻度灰霾日、中度灰霾日到重度灰霾日的接地逆温层厚度逐渐增大,逆温层出现高度逐渐降低,逆温层强度逐渐增强。当出现灰霾天气时,大气中细粒子较多,气溶胶质量浓度、体积浓度、黑碳浓度和气溶胶散射系数均比非灰霾天气时高。冬季黑碳浓度最大,细粒子所占比例最高。春季气溶胶质量浓度最大,大颗粒气溶胶最多。在利用导数法、归一化导数法和小波斜方差变换法反演边界层高度的三种方法中,用小波协方差变换法反演边界层得到的结果最好。在气象条件相同,气溶胶含量一定的情况下,能见度与边界层高度的变化趋势一致,但最大边界层高度出现的时间比最大能见度出现的时间早。夏季边界层最高,其次为秋季,春季和冬季边界层高度相近,为最低。重度灰霾时边界层高度小于650m,中度灰霾时为500-850m,轻度灰霾时为550-1100m,非灰霾时为850-1200m。CALIPSO观测结果与地面结果一致。在长三角地区,出现灰霾天气时,气溶胶大多集中在2km以下的区域内。在这个高度范围内,消光后向散射值主要集中在0.001-0.003 km^-1·sr^-1范围内,退偏比值主要集中在0-20%之间,色比值主要集中在0.2-0.9之间。对春、秋、冬三季样本进行统计时发现,消光后向散射在春季最小,体积退偏比和色比春季最大,秋季最小。这反映出春季受到北方沙尘输送的影响,导致春季灰霾天气的气溶胶颗粒比其他季节大,且颗粒较不规则,而秋季主要是较规则的小尺度气溶胶颗粒。出现灰霾天气时,越接近地面颗粒尺度越大,且颗粒越不规则。更多还原

【Abstract】 In this paper, haze aerosols physical characteristics in Shanghai which was one of the most severely haze-affected areas in China were analyzed. First, the meteorological data and aerosol ground observation from Shanghai Meteorological Bureau were used to analyze climatic characteristics and meteorological cause of haze as well as physical characteristics of aerosols during haze periods. Then the height of boundary layer was retrieved and its variation for different intensity haze was analyzed using data from ground-Micro Pulse Lidar. The vertical distributions of aerosols in haze at Yangtze River Delta region were presented based on. the advanced CALIPSO satellite observations.The result showed that the multiyear average number of haze days per year was about 154.6 in Shanghai. Annual variation of haze was evident. November, December and January showed high occurrence of haze. Haze occurred most frequently in spring and winter, mild haze in spring and severe haze in winter. Wind direction, wind speed, precipitation and number of precipitation days all had an affinity with the occurrence of haze. When westerly, southwest or northwest winds blowed in Shanghai, there was higher occurrence of haze, while north, northeast east or south-east wind could purify atmosphere leading to less haze. Thickness and intensity of inversion layer influenced on haze. From mild haze to moderate one and then to severe haze, thickness of inversion layer from surface increased gradually while the height decreased and intensity increased gradually. During haze periods, there were more fine particles in the atmosphere and aerosol mass concentration, volume concentration, black carbon concentration and aerosol scattering coefficient were higher than those during non-haze periods. The highest concentration of black carbon and proportion of fine particles occurred in winter while the largest measurement of mass concentration and coarse particles of aerosols were in spring.Among the derivative-based method, normalized oblique derivative method and wavelet covariance transform method, the third can obtain the best result of boundary layer height retrieval. Under the same weather conditions and aerosol content, visibility and boundary layer height had a consistent variation trend. But the highest boundary layer height appeared earlier than the maximum visibility. The maximum boundary layer height appeared in summer, followed by the fall and the lowest was in spring and winter. When severe haze appeared, the boundary layer height was less than 650m, while the corresponding height was between 550-850m during moderate haze, 550-1100m during light haze and 850-1200m during non-haze periods.Observations from CALIPSO data were consistent with that of ground-based. In the Yangtze River Delta region, when haze occurred, aerosols were mostly concentrated below 2km altitude. Within such a height, back scattering coefficient mainly ranged from 0.001 to 0.003km^-1·sr^-1, depolarization ratio ranged from 0 to 20% and color ratio ranged from 0.2 to 0.9. Based on the statistics for spring, autumn and winter, attenuated back scattering in spring was smallest, depolarization ratio and color ratio in spring were largest. Due to dust transport from north in spring, there were relatively large particles with irregular shape during haze periods, in autumn, aerosol particles were smaller and more regular than the other two seasons. When haze occurred, the lower the altitude was, the larger and more irregular the particles were.更多还原