Collaborative Research: West African Mesoscale Convective Systems and Their Interactions with the Synoptic Environment

中尺度对流系统(MCS)与西非上空天气尺度环境之间的相互作用对于确定该区域天气和气候的性质和可变性至关重要。除了在影响西非降雨方面发挥重要作用外，中尺度和天气尺度天气系统(非洲东风波)在调动和输送沙尘方面也起着关键作用。对尺度相互作用，包括它们对尘埃的影响的一般了解很差，到目前为止，由于缺乏有用的观测，一直受到严重阻碍。这项研究的相关总体目标是：(I)提高我们对MCSs与天气环境之间相互作用的认识和理解，以及(Ii)提高对MCSs和AEW在动员和输送沙尘中所起作用的认识和理解。解决这两个目标的核心智力功劳是作为非洲季风多学科分析(AMMA)的一部分进行的特别观察，这是2006年夏季在西非开展的一项特别观察活动。对这项研究特别重要的是麻省理工学院多普勒雷达的观测结果。PIS将利用这些观测数据来突出MCS强度和结构的性质和可变性。这项工作的一个特别新颖的方面是对与MCS通道相关的4维非绝热加热场的估计。这些加热场对中尺度位涡结构的影响将通过在WRF区域模式的理想化版本中施加非绝热加热场(由观测指导)来研究。将开展一项个案研究，探索与2006年夏季AEW和嵌入的MCS通过有关的光伏领域的多尺度方面--这是以前不可能做到的。麻省理工学院的雷达数据还将与几项ARM(大气辐射测量)观测相结合，包括95 GHz垂直指向的多普勒雷达，以详细探讨尘埃是如何随着MCSs的通过而动员起来的。这一分析将与上文讨论的天气环境的性质进行比较，并将有助于阐明萨赫勒和撒哈拉沙尘在西非(和热带大西洋)观测到的沙尘总量中的相对贡献。更广泛的影响这项研究产生了广泛的影响，包括：-提高对西非季风关键天气系统的认识和理解。-教育和培训三名研究生，他们将发展他们对天气和气候的理解以及他们在数据分析和建模方面的技能。-通过在天气系统到达热带大西洋和前往美国之前提供详细的天气系统分析，帮助了解西非天气气候的可变性如何影响下游的热带气旋生成。

The interactions between mesoscale convective systems (MCSs) and the synoptic scale environment over West Africa are crucial for determining the nature and variability of the weather and climate of the region. In addition to their important role in influencing West African rainfall, the mesoscale and synoptic scale weather systems (African easterly waves, AEWs) also have a key role in mobilizing and transporting dust. General understanding of the scale interactions including their impact on dust is poor and has until now been severely hindered by lack of useful observations. The related overarching aims of this research are: (i) To improve our knowledge and understanding of the interactions between MCSs and the synoptic environment, and (ii) to improve knowledge and understanding of the role MCSs and AEWs play in mobilizing and transporting dust. Intellectual Merit Central to addressing both aims are the special observations that were made as part of the African Monsoon Multidisciplinary Analysis (AMMA), a special observing campaign over West Africa in summer 2006. Of particular importance to this research are the observations from the MIT Doppler radar. These observations will be used by the PIs to highlight the nature and variability of the intensity and structure of the MCSs. A particularly novel aspect of this work is the estimation of the 4-dimensional diabatic heating fields associated with the MCS passages. The impact these heating fields have on mesoscale potential vorticity structures will be investigated by imposing diabatic heating fields (guided by the observations) in an idealized version of the WRF regional model. A case study will be carried out that explores the multi-scale aspects of the PV field associated with the passage of an AEW and embedded MCSs during the summer of 2006 - something that has not been possible previously. The MIT radar data will also be combined with several ARM (Atmospheric Radiation Measurements) observations, including the 95 Ghz vertically-pointing Doppler radar, to explore in detail how the dust is mobilized in association with the passage of the MCSs. This analysis will be compared to the nature of the synoptic environment, discussed above, and will help to shed light on the relative contributions of Sahelian and Saharan dust to the total dust amounts observed over West Africa (and the tropical Atlantic). Broader impacts The research has broad impacts that include:- Improving knowledge and understanding of the key weather systems in the West African Monsoon. - Educating and training three graduate students who will develop their understanding of weather and climate as well as their skills in data analysis and modeling. - Contributing to knowledge of how the variability of West African weather climate impacts downstream tropical cyclogenesis, through providing detailed analysis of the weather systems before they reach the tropical Atlantic and head for the U.S.