【作者】 彭杰；

【导师】 张华；

【作者基本信息】 南京信息工程大学 ， 气象学， 2013， 博士

【摘要】 云自身的辐射效应和云与气溶胶相互作用的辐射效应对于气候系统中的辐射过程有着十分重要的影响,且两者目前是预测未来气候变化中最大的不确定性的来源之一。因此,本文通过结合主动被动卫星遥感资料和次网格随机云生成器,一方面分析云重叠问题中的重要参数—抗相关厚度的时空分布,为未来气候模式发展更精确的参数化方案提供基于卫星观测的参考；另一方面分析全球深厚云系统的时空分布,选取最适合研究气溶胶激活效应的热带地区,研究气溶胶对于不同类型云的影响,特别着眼于以往研究中较少涉及到的对云辐射强迫的影响。主要结论如下：1)表征云垂直结构的特征量一抗相关厚度具有明显的时空变化。简单地将其设定值为2km对次网格气柱总云量进行模拟时,会产生平均约为15%左右的误差,这些误差会对气候模式中云辐射计算和辐射收支平衡产生很大影响。因此,对于抗相关厚度的精确参数化是未来气候模式发展中的重要方向之一。2)伞球不同纬度带上的深厚云系统及其宏观物理特性具有非常不同的分布特点。随着纬度的升高,深厚云系统的垂直发展强度逐渐减弱,而水平覆盖面积逐渐加强。两者不同的伞球分布体现出不同纬度带上深厚云系统形成的主导机制不同：低纬度地区的深厚云系统多为深对流云,因而具有最强的垂直发展和最弱的水平发展。中纬度地区的深厚云系统多为锋面成云,垂直发展强度小于低纬地区,受季风影响的北半球中纬度地区,垂直发展强度在北半球夏季有明显增大；而高纬地区的深厚云系统主要由来自极地的冷气团和副热带的暖气团交汇形成的大范围锋面而产生,其垂直对流弱,因此其水平发展强度最大,垂直发展强度最小。3)对热带地区气溶胶对云宏观和微观特性影响的分析表明：随着气溶胶浓度的增加,水云的宏观相态无明显改变,而混合相态云的云顶高度和云层厚度显著增加,同时,混合相态云中的冰过程显著增强,而三种不同类型云的云滴的有效半径都呈减小的趋势,这些结果与理论上气溶胶激活效应对云宏观和微观特性的改变均相符,证实了热带地区气溶胶激活效应的存在；对气溶胶对云辐射强迫(CRF)的分析表明：随着气溶胶浓度的增加,水云的长波CRF并无显著的改变,与其宏观特性的改变相一致,气溶胶第一间接效应和半直接效应共同作用导致短波CRF呈先增长后减弱的趋势；混合相态云的短波CRF和长波CRF均显著增加,这是由于气溶胶激活效应导致云层变厚,云顶变高,从而反射更多的太阳短波辐射回太空,同时捕获更多的地表长波辐射。此外,本文采用简单的基于样本个数权重的计算方法初步估算出气溶胶对热带地区云辐射强迫的净影响为-4.18W/m2；对多个气象要素和气溶胶浓度相关性的分析表明：气溶胶增加导致的云微物理特性和辐射特性的显著改变并不能由大尺度动力条件所解释。更多还原

【Abstract】 The radiation impact of clouds and the interaction between clouds and aeorosols play a key role in the radiation processing in climate system. But they are still one of the biggest uncertainties in the climate prediction due to many reasons. Therefore, by the combination of active and passive remote sensing and the stochastic cloud generator, we first analyzed the spatial and temporal distribution of an important parameter in cloud overlapping parameterizations-decorrelation depth which can be used as reference for the development of new parameterization in the future. On the other hand, we performed a statistical analysis of global deep cloud systems, and studied the aerosol invigoration effect on tropical clouds with special focus on the impact of invigoration effect on cloud radiative forcing (CRF). The mainly findings are:1) The decorrelation depth which represents the cloud vertical structure has significant temperol and spatial variations. Simply fix it to2km will result about15%differences between simulated and observed column cloud amount. The differences would have significant impact on the cloud radiation calculation and radiation budget in climate model. Therefore precisely parameterization of decorrelation depth is one of the major direction for climate model development infuture.2) The macro-physical properties of global deep cloud systems (DCS) have very different characteristics in different latitudes. The vertical (horizontal) development of DCS increase (decrease) towards higher latitudes, which indicate the different mechanism of DCSs’ generation. Most of the DCS in low latitudes are deep convective cloud which highly developed in vertical direction but cover relative small horizontal extent, therefore have the strongest vertical development but weekest horizontal development. DCS in middle latitudes are mainly caused in front system thus have weaker vertical development than those in low latitudes. Influenced by the mooson, the vertical developments of DCS increase sharply in summer of north hemisphere. The DCS in high latitudes are formed in the large scale front system formed by the convergence of warm air mass from sub-tropical region and cold air mass from polar region. Therefore they have the weekest vertical development but strongest horizontal development.3) The analyzing of the aerosol impact on the macro and micro physical properties of tropical clouds indicate that: with the increase of aeorosol loading, no obviously change shows for liquid cloud, but the cloud top height and cloud thickness of mixed-phase clouds increase significantly and their ice processing are stronger as well while the effective radius of all types of clouds are decrease. The agreements of all above clouds’properties change with aerosol are consist with aerosol invigoration effect hypothesis, which give the provement of the exsiting of aerosol invigoration effect on tropical clouds. The analyzing of the relationship between aerosol and CRF demonstrate that: with the increase of aerosols, no obviously change of longwave CRF for liquid clouds which is consist with no change of its geomoety. But due to the combination of first indirect effect and sem-direct effect, the shortwave CRF of liquid clouds increase first and decrease after. Both shortwave CRF and longwave CRF of mixed-phase clouds increase significant with the increase of aeorosols. That is because invigorated cloud will have higher cloud top and thicker cloud thickness, therefore would reflect more solar radiation back to space and capture more longwave radiation from surface. Using a simple sample number weighted calculation method, the aerosol net effect of all the clouds in tropical regions are estimated to be-4.18W/m2. Further tests on the dependence of multiple meteorological parameters shows that, the targeted relationship between cloud physical and radiative properties can not be explained by dynamical impact.更多还原