Effects of Saharan Dust on the African Easterly Jet-African Easterly Wave System

撒哈拉沙尘对非洲东急流-非洲东风波系统的影响

• 批准号: 1624414
• 负责人: Terrence Nathan
• 金额: $ 59.86万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-03-01 至 2023-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1624414&HistoricalAwards=false
• 关键词: Effects; Saharan; Dust; African; Easterly

North Africa is home to the African easterly jet, a current of strong easterly winds located in the lower atmosphere. The African easterly jet often gives birth to weather systems known as African easterly waves. Together the jet and the waves form a complex system whose influence on weather can extend to the United States. That influence often manifests as tropical cyclones, whose genesis has been linked to the easterly waves. Consequently, to understand the connection between the weather over North Africa and the development of tropical cyclones, it is important to understand the processes that affect the African easterly jet‒African easterly wave system. Of those processes, the heating effects of Saharan dust storms are among the least understood, yet potentially among the most important. The central objective of this proposal is to advance understanding of the effects of Saharan dust storms on the intra-seasonal and inter-annual variability of the African easterly jet‒African easterly wave system. To achieve this objective, a unified work plan is developed that combines numerical experiments, observational analysis, and model verification. To guide the numerical experiments and to aid in the interpretation of the results, a theoretical framework will be developed that exposes the dust-modified physics operating within the system. The scientific merits of the proposed research include: understanding the pathways that communicate the effects of Saharan dust to the African easterly jet‒African easterly wave system; providing a physical basis for explaining how Saharan dust affects the temporal variability of the system; and evaluating the importance of Saharan dust to the life cycles of the easterly waves. The broader impacts of the proposed research include: additional understanding of how Saharan dust affects the circulation over North Africa, which will aid the scientific community?s efforts to improve weather forecasts for the region; improved representation of the dust-modified system, which will benefit future studies that seek to advance understanding and improve forecasting of tropical cyclones over the Eastern Atlantic Ocean; development of a theoretical framework for understanding the dust-modified circulation, which can be used as an interpretive tool for numerical modeling and observational studies of the weather over North Africa; and the scientific training of undergraduate and graduate students in the discipline of atmospheric sciences.

北非是非洲东风急流的所在地，这是一种位于低层大气的强烈东风气流。非洲东风急流经常产生被称为非洲东风波的天气系统。喷射和波浪共同形成了一个复杂的系统，其对天气的影响可以延伸到美国。这种影响通常表现为热带气旋，其起源与东风波有关。因此，要了解北非天气与热带气旋发展之间的联系，了解影响非洲东风急流（非洲东风波系统）的过程非常重要。在这些过程中，撒哈拉沙尘暴的加热效应是人们最不了解的，但可能是最重要的。该提案的中心目标是加深对撒哈拉沙尘暴对非洲东风急流（非洲东风波系统）季节内和年际变化的影响的了解。为了实现这一目标，制定了结合数值实验、观测分析和模型验证的统一工作计划。为了指导数值实验并帮助解释结果，将开发一个理论框架，揭示系统内运行的灰尘修改物理现象。拟议研究的科学价值包括：了解撒哈拉沙尘对非洲东风急流（非洲东风波系统）影响的途径；为解释撒哈拉尘埃如何影响系统的时间变化提供物理基础；并评估撒哈拉沙尘对东风波生命周期的重要性。拟议研究的更广泛影响包括：进一步了解撒哈拉沙尘如何影响北非上空的环流，这将有助于科学界努力改善该地区的天气预报；改进了沙尘修改系统的代表性，这将有利于未来的研究，旨在增进对东大西洋热带气旋的理解和改进预报；开发一个理解沙尘影响环流的理论框架，该框架可用作北非天气数值模拟和观测研究的解释工具；以及大气科学学科本科生和研究生的科学培训。