气溶胶云下雨洗过程中的动力学机制研究

项目名称： 气溶胶云下雨洗过程中的动力学机制研究

项目编号： No.41275157

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 天文学、地球科学

项目作者： 亢燕铭

作者单位： 东华大学

项目金额： 84万元

中文摘要： 研究表明，大气气溶胶通过辐射强迫对气候产生直接或间接影响，因而具有强烈的气候和环境效应。气溶胶沉积会向地表生态系统增加环境负荷，并与许多城市大气污染引起的问题有关。在许多模式研究中，对气溶胶清除过程的估计上存在着很大的不确定性。这些不确定性主要是由于对湿清除的表达不同而产生的。 本研究将考虑有关模式研究中对云下气溶胶雨洗过程估计的要求，根据流体和气溶胶动力学基本理论，考虑全区间气溶胶粒径分布，在粘性流和势流模型下，对粒子在雨滴表面的捕集问题，采用统一背景流场，严格分析在扩散、拦截、惯性碰撞和泳力场联合作用时，气溶胶在雨滴的表面捕集效率，以解决或改进已有研究中，对粒子捕集过程描述的背景流场不一致问题、及由此导致的捕集效率理论值过低问题。在这一基础上，针对湍流背景场，对雨洗气溶胶过程进行整体模拟，考察湍流对实际捕集过程的增益效应。通过对层流和湍流情况的求解，修正捕集效率偏低的理论表述。

中文关键词： 云下雨洗；气溶胶；捕集效率；湍流效应；数值模拟

英文摘要： It has been known that atmospheric aerosols have strong impacts on climatic and environmental issues. Through radiative forcing, aerosols have direct (scattering or absorption of solar radiation) and indirect (increasing cloud condensation nuclei (CCN)) effects on climate. The deposition of aerosols delivers atmospheric loads of many compounds to ecosystems. Atmospheric aerosols are also responsible for many urban-air-pollution-related problems. Aerosol removal processes remain an important source of uncertainty in many modeling studies, such as the global aerosol transport models, global chemical transport models and air quality models. Obviously, Precipitation scavenging of atmospheric aerosol particles is an important removal process that should be included in the models mentioned above. A parameter known as the scavenging coefficient has been used in the aerosol mass continuity equation in those models to represent below-cloud particle scavenging. To understand thoroughly these problems, aerosol emission, transport, transformation, and removal mechanisms should be quantified at multiple scales. Either the earlier or some of the current models only dealt with bulk aerosol mass without the complexity of the relationships between aerosols and rain drops such as size-resolved number and mass concentrations, the

英文关键词： below-cloud scavening；aerosol；collection efficiency；turbulent effect；numerical simulation