上海地区气溶胶对低层暖云的影响机制及气溶胶—云辐射效应研究

发布时间：2018-05-02 16:03

本文选题：气溶胶光学厚度 + 气溶胶类型　；参考：《东华大学》2017年博士论文

【摘要】：气溶胶-云-辐射的作用机制是大气科学领域亟需解决的重大科学问题之一。本文利用“A-Train”卫星编队中的Aqua和CALIPSO卫星联合观测,以及时间上形成互补的上午星Terra和下午星Aqua上共同搭载的MODIS传感器,获得的气溶胶和云以及气象要素信息,同时利用地面微脉冲激光雷达提供的气溶胶垂直信息,建立上海地区气溶胶-云数据库,分析上海地区气溶胶三维时空分布特征,研究气溶胶对低层暖云的影响机制,并探讨气溶胶层与云层在垂直方向上的距离对气溶胶-云相互作用的影响,最后利用最新的Accu RT辐射传输模式系统定量评估气溶胶和云的辐射效应。主要的结论如下:(1)基于MODIS十年观测数据可知,整个上海中心城区和大部分郊区的气溶胶光学厚度(AOD)均值在0.9~1.0之间,其中,中心城区以细粒子气溶胶污染为主,郊区则以粗粒子为主。气溶胶的季节变化明显,夏季气溶胶污染最重,春季和冬季次之,秋季最轻。春季,受到北方沙尘天气的影响,上海地区近地面和高空(3 km以上)均出现了较多的矿物沙尘型气溶胶,且高空多于近地面。夏季气溶胶细粒子的贡献明显多于其他季节,这与二次有机气溶胶的增多密切相关,污染沙尘型、污染大陆型(即城市/工业型)和烟尘型气溶胶是主要污染类型,均为本地及周边排放产生。秋季出现的气溶胶也不涉及长距离输送,多为局地产生的污染沙尘型、污染大陆型和烟尘型气溶胶等。冬季,上海的高空出现了一定的烟尘型气溶胶,这与北方突发性的霾污染事件有关,另外,污染沙尘型和污染大陆型气溶胶也是主要的气溶胶类型。(2)霾和浮尘污染的对比研究表明,霾期间的气溶胶主要由本地污染源产生,垂直方向上沿着高度逐渐抬升,气溶胶消光作用在抬升过程中逐渐减弱;浮尘天气的气溶胶则主要是受到远距离传输的影响,并由高空向地面沉降,在沉降过程中消光作用逐渐增强。浮尘气溶胶的AOD均值略高于霾气溶胶,但是,低空霾气溶胶的消光系数大于浮尘气溶胶。此外霾天气边界层高度和污染状况互相影响,而浮尘天气污染情况受大气边界层影响较小。(3)气溶胶光学厚度、云量(CF)、水汽总量(WV)和K指数(K)呈现相似的年变化特征,年内最大值均出现在夏季,但云量的最大峰值出现的时间略滞后于气溶胶光学厚度。水汽总量和大气稳定度对云的水平和垂直发展影响要大于气溶胶对其的影响。水汽含量越多、大气越不稳定,越利于云的发展。随着大气稳定程度的减弱,气溶胶对云量的影响也迅速减弱;但气溶胶对云顶气压的影响有增强趋势。排除气象条件的影响,上海地区气溶胶的增多会导致云量的减少、云顶气压值的减小、云顶高度的增加,不利于云的水平发展,但有利于云的垂直向上发展。(4)气溶胶光学厚度对云粒子等效半径的影响与云液态水含量(LWP)、水汽总量(WV)及气溶胶层与云底的垂直距离(△H)密切相关。研究表明,上海地区气溶胶对云粒子大小的影响既遵循“Twomey”效应,又出现了反“Twomey”效应,这主要是由于不同的LWP造成的。当LWP50 g m-2,云粒子随着LWP的增大迅速增大,出现反“Twomey”效应;当50 g m-2LWP150 g m-2,云粒子等效半径随着气溶胶的增多而减小,遵循“Twomey”效应。而WV和△H对气溶胶的第一间接效应影响很大,水汽含量越多,气溶胶对云粒子等效半径的影响越小,水汽含量越少,气溶胶对云粒子等效半径的影响越大;随着△H的增加,气溶胶与云的相关性逐渐减弱,当二者距离大于150 m,几乎无相关性。(5)无论是在大气层顶、大气中还是地表处,上海地区气溶胶的短波辐射效应均表现为冷却作用,辐射强迫的绝对值随着高度的下降逐渐增大,气溶胶在地表的冷却作用要强于大气层顶。在大气层顶,云的短波辐射强迫因受到气溶胶的影响而削减,云的冷却作用受到了抑制;在地表,气溶胶的存在反而加强了云的短波辐射冷却效应,共同使地表降温。气溶胶和云都能增强大气吸收率,削减达到地面的太阳辐射,对地表起冷却作用,而且云层的出现对其上层和下层大气的吸收率都有影响,其对云上大气的吸收率的影响要大于云下大气。
[Abstract]:The action mechanism of aerosol cloud radiation is one of the most important scientific problems to be solved in the field of atmospheric science. This paper uses the joint observation of Aqua and CALIPSO satellites in the "A-Train" satellite formation, and the MODIS sensors co loaded on the complementary morning star Terra and the afternoon star Aqua, and the aerosol and cloud and gas obtained by the formation of the complementary morning star Terra and the afternoon star Aqua. Like element information and using aerosol vertical information provided by ground micro pulse lidar, the aerosol cloud database in Shanghai area is established, the three-dimensional spatial and temporal distribution characteristics of aerosol in Shanghai area are analyzed, the influence mechanism of aerosol on the low layer warm cloud is studied, and the distance between aerosol layer and cloud layer in the vertical direction is discussed. The influence of interaction, finally using the latest Accu RT radiation transmission model system to quantify aerosol and cloud radiation effects. The main conclusions are as follows: (1) based on the MODIS ten year observation data, the mean value of aerosol optical thickness (AOD) in the central and most suburban areas of Shanghai is between 0.9~1.0, of which the central urban area is fine. The main aerosol pollution is particle aerosol, and the suburb is dominated by coarse particles. The seasonal change of aerosol is obvious, the aerosol pollution is the heaviest in summer and the lowest in spring and winter. In spring, it is affected by the sand dust weather in the north. In Shanghai area, there are more mineral dust aerosols near the ground and above the altitude (3 km above), and the altitude is more than near the near. The contribution of aerosol fine particles in summer is more than that of other seasons, which is closely related to the increase of two organic aerosols. The main pollution types are contaminated sand dust type, pollution continental type (city / industrial type) and smoke aerosol type, which are both local and peripheral emissions. In winter, a certain amount of smoke and dust aerosol appeared in Shanghai, which is related to the sudden haze pollution in the north. In addition, the polluted and polluted continental aerosols are also the main aerosol types. (2) a comparative study of haze and dust pollution The aerosol in the haze period is mainly produced by the local pollution source, rising gradually along the height in the vertical direction. The aerosol extinction effect is gradually weakened during the uplifting process. The aerosols in the floating dust weather are mainly affected by the long distance transmission, and the sedimentation process is gradually enhanced. The AOD mean value of the gel is slightly higher than the haze aerosol, but the extinction coefficient of the low altitude haze aerosol is greater than that of the dust aerosol. In addition, the boundary layer height and pollution condition of the haze weather affect each other, and the dust weather pollution is less affected by the atmospheric boundary layer. (3) the aerosol optical thickness, cloud amount (CF), the amount of water vapor (WV) and the K index (K) show similar years. The maximum peak value of the annual variation appears in summer, but the maximum peak time of the cloud is lagging behind the aerosol optical thickness. The effect of water vapor and atmospheric stability on the level and vertical development of the cloud is greater than that of the aerosol. The more the water vapor content, the more unstable the atmosphere is, the more conducive to the development of the cloud. With the stability of the atmosphere, the more the atmospheric stability is. The effect of aerosol on cloud top pressure has a tendency to increase rapidly. However, the effect of aerosol on cloud top pressure is enhanced. The increase of aerosol in Shanghai region will lead to the decrease of cloud amount, the decrease of cloud top pressure and the increase of cloud top, which is not conducive to the development of cloud level, but is beneficial to the vertical upward of cloud. (4) the effect of aerosol optical thickness on the equivalent radius of cloud particles is closely related to the cloud liquid water content (LWP), the total amount of water vapor (WV) and the vertical distance (delta H) of the gas soluble film and cloud bottom (delta H). The study shows that the effect of aerosol on the size of cloud particles in the Shanghai area follows the "Twomey" effect, and the anti "Twomey" effect appears mainly. It is caused by different LWP. When LWP50 g m-2, the cloud particles increase rapidly with the increase of LWP, and there is an anti "Twomey" effect. When 50 g m-2LWP150 g m-2, the equivalent radius of the cloud particles decreases with the increase of aerosols and follows the "Twomey" effect. The smaller the effect of the sol on the equivalent radius of the cloud particles, the less the water vapor content, the greater the effect of aerosol on the equivalent radius of the cloud particles. With the increase of delta H, the correlation between aerosols and clouds gradually weakened. When the distance between the two is greater than 150, there is almost no correlation. (5) in the top of the atmosphere, in the atmosphere or at the surface, the aerosol in Shanghai area The effects of short wave radiation are all cooling, the absolute value of the radiation forcing increases gradually with the height, and the cooling effect of the aerosol on the surface is stronger than the top of the atmosphere. The cooling effect of the short wave radiation of the cloud is strengthened and the surface temperature is cooled together. Aerosols and clouds can increase the absorption rate of the atmosphere, reduce the solar radiation reaching the ground and play a cooling effect on the surface, and the appearance of the clouds has an influence on the absorption rate of the upper and lower atmosphere, and its influence on the absorption rate of the upper atmosphere is greater than that under the cloud. Gas.

【学位授予单位】：东华大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X513;P426.5

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