Collaborative Research: Impacts of Mineral Dust on the Lifecycle of Tropical Convection

将通过观测分析和数值模拟相结合的方法研究矿物粉尘在热带大西洋盆地有组织对流云系统中作为云凝结和冰核的影响。理想化的模拟将使用区域大气模拟系统（RAMS）进行，以进一步检查尘埃气溶胶对热带对流云和降水的影响，并以NAMMA期间收集的观测数据为指导，NAMMA是美国宇航局的非洲季风多学科活动项目，在2006年大西洋飓风季节进行。一场实际风暴（热带风暴黛比）的生命周期将被详细模拟，它显然受到东大西洋上撒哈拉沙尘的影响。将研究撒哈拉空气层（SAL，它从非洲向西携带沙尘）的动力和辐射影响，并将评估直接和间接气溶胶效应的相对重要性以及SAL本身的环境影响——包括湿度、温度和垂直风切变。2010年，美国国家科学基金会（nsf）支持的热带云系统低气压前调查（PREDICT, Pre-Depression Investigation of cloud systems in the Tropics）实验将对到达大西洋西部深处深层对流云团的年老尘埃的观测结果进行检验。这项工作的智力价值在于，在受到来自遥远大陆地区的尘埃和其他气溶胶影响的情况下，改进了对云过程（特别是云和降水微物理学）的理解，并确定了这些影响在多大程度上有利于或不利于热带风暴和飓风的形成。通过从代表性不足的群体（即大气科学领域的妇女）中选出的两名主要研究人员的支持，通过大学培训和研究生实地经验的结合，以及最终通过提高预测热带风暴形成和/或强度的沙尘引起的变化的能力，对准确预报大西洋盆地飓风至关重要，将产生更广泛的影响。

The effects of mineral dust acting as both cloud condensation and ice nuclei within organized convective cloud systems over the tropical Atlantic basin will be investigated through a combination of observational analysis and numerical simulations. Idealized simulations will be conducted using the Regional Atmospheric Modeling System (RAMS) to further examine dust aerosol impacts on tropical convective clouds and precipitation are to be guided by observations collected during NAMMA, NASA's African Monsoon Multidisciplinary Activities project, conducted during the 2006 Atlantic hurricane season. The lifecycle of an actual storm (Tropical Storm Debby), which was apparently influenced by ingestion of Saharan dust over the eastern Atlantic, will be simulated in detail. The dynamical and radiative impacts of the Saharan Air Layer (SAL, which carries dust westward from Africa) will be studied, and the relative importance of direct and indirect aerosol effects as well as environmental influences of the SAL itself--including humidity, temperature and vertical wind shear--will be assessed. Observations of aged dust reaching the far western Atlantic upon deep convective clouds in that region will be examined using additional observations from the NSF-supported PREDICT (Pre-Depression Investigation of Cloud-systems in the Tropics) experiment in 2010.The intellectual merit of this effort centers on improved understanding of cloud processes (and in particular cloud and precipitation microphysics) in the presence of influences by dust and other aerosols originating over distant continental regions, and determination of the extent to which these influences may favor or disfavor tropical storm and hurricane formation.Broader impacts will come through support of two principal investigators drawn from an underrepresented group (viz. women in the atmospheric sciences), through a combination of university training and field experience for a graduate student, and ultimately through improved ability to anticipate dust-induced changes in tropical storm formation and/or intensity key to accurate forecasts of Atlantic basin hurricanes.