Understanding High-Impact Rainfall Events over the West African Sahel: Resolving the Role of Environmental Conditions on Storm Processes

虽然洪水是一个涉及气象系统和地表条件的复杂过程，但大多数高影响事件的特点是总降雨量大。这项研究的重点是了解在西非萨赫勒地区带来高降雨量的风暴系统，这是一个已知的相对偏远的地区，由于频繁发生强降雨和相对较低的适应能力，特别容易受到洪水的影响。首要目标是通过调查环境条件如何促成这类风暴的发展，促进我们对西非萨赫勒地区极端降雨产生系统发展的实际了解。鉴于高影响降雨事件对西非人民生计的影响，以及这些系统在西非萨赫勒地区大西洋飓风中的已知作用，从这项研究中获得的知识不仅将有助于改进对西非萨赫勒地区高影响降雨事件的预测，而且将有助于改进对我国国家利益的天气预报。该项目还通过吸引和培训一名博士后研究员和一名研究生，以及通过K-12外联方案，为下一代大气科学家的教育作出贡献。该项目的具体目标是：(1)了解提供高影响降雨量的降水系统的特征；(2)确定有利于这些降雨事件发展的环境条件。这些目标将通过利用高分辨率卫星衍生的降雨产品、最先进的大气再分析数据以及允许对流的区域气候模拟来实现。将使用来自卫星的降雨量估计和地面观测来确定和描述该区域的高影响降雨事件，并将这些事件与地面真实情况相互参照，以确定与报告的洪灾有关的事件。大气再分析数据和允许对流的模型将被用来确定与强烈风暴相关的环境条件，并开发和测试关于它们如何相关的假设，以加深我们对与高影响降雨事件发展相关的物理过程的理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

While flooding is a complex process involving both meteorological systems and surface conditions, most high-impact events are characterized by high rainfall totals. This study focuses on understanding storm systems that deliver high rainfall amounts over the West African Sahel, a relatively remote region known to be particularly vulnerable to flooding due to the frequent occurrence of intense rainfall and relatively low adaptive capacity. The overarching goal is to advance our physical understanding of the development of extreme rainfall-producing systems over the West African Sahel by investigating how environmental conditions contribute the development of such storms. Given the consequences of high-impact rainfall events for the livelihoods of West Africans, as well as the known role of these systems over the West African Sahel in Atlantic hurricanes, the knowledge gained from this study will be valuable for improving not only the prediction of high-impact rainfall events over the West African Sahel but also the weather forecast for our own national interests. The project also contributes to the education of the next generation of atmospheric scientists through involving and training a post-doctoral researcher and a graduate student as well as through a K-12 outreach program. The specific objectives of this project are: (1) to understand the characteristics of precipitating systems that deliver high-impact rainfall amounts; and (2) to determine the set of environmental conditions that favor the development of these rainfall events. These objectives will be addressed by utilizing high-resolution satellite-derived rainfall products, state-of-the-art atmospheric reanalysis data, along with convection-permitting regional climate modeling. Satellite-derived rainfall estimates and ground-based observations will be used to identify and characterize high-impact rainfall events over the region, and these will be cross-referenced with ground-truth to identify events associated with reported flooding. Atmospheric reanalysis data and convection-permitting modeling will be used to identify the environmental conditions associated with intense storms, and to develop and test hypotheses regarding how they are related to deepen our understanding of the physical processes associated with the development of high-impact rainfall events.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.