AGS-PRF: Direct Radiative Effects of Saharan Dust on the Dynamics of the African Easterly Jet and African Easterly Waves

AGS-PRF：撒哈拉沙尘对非洲东风急流和非洲东风波动力学的直接辐射影响

基本信息

批准号：
1524767
负责人：
Dustin Grogan
金额：
$ 8.6万
依托单位：
Grogan Dustin F
依托单位国家：
美国
项目类别：
Fellowship Award
财政年份：
2015
资助国家：
美国
起止时间：
2015-10-01 至 2018-01-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1524767&HistoricalAwards=false
关键词：
AGS PRF Direct Radiative Effects

项目摘要

The large-scale atmospheric circulation over North Africa during summer is characterized by three striking features: the African easterly jet (AEJ); African easterly waves (AEWs); and large plumes of Saharan mineral dust aerosols. The central objective of this research is to determine the effects of Saharan dust on the linear dynamics and nonlinear evolution of the AEJ-AEW system. To achieve this objective, several tasks that will be carried out to answer the following questions: Can dust-radiative heating destabilize an otherwise stable AEJ (or vice versa)? If so, what aspects of the dust - concentration, spatial gradients, emission variability, etc. - affect the linear stability of the AEJ? How does the dust physics manifest in terms of the spatial structure and energetics of the AEJ? Are there particular locations and combinations of dust concentration and distribution that will optimize the linear growth (or decay) of AEWs? As the AEWs grow to finite amplitude, how does the dust affect their structure? Are there particular locations and combinations of dust concentration and distribution that will optimize the development of AEWs? And how does the AEJ-AEW system respond to a time varying dust plume, one that varies either periodically or episodically?To answer these questions, and others, the Weather Research and Forecasting (WRF) model, which is coupled to a dust tracer model, will be used to run a systematic sequence of experiments with and without dust. The data from the simulations will be analyzed and compared using standard methods. The analyses will provide information on the effects of dust on the following: growth rate, propagation, and structure of AEWs; formation of critical layers, which have been shown to play a role in tropical cyclogenesis; and local and global energetics of the AEJ-AEW system.Intellectual Merit:The intellectual merit of the research includes: advancing understanding of how Saharan dust-radiative feedbacks, which depend on a combination of the dust concentration and its spatial distribution, affect the linear growth and nonlinear development of AEWs; developing insights into the relationship between the spatial-temporal variability of Saharan mineral dust and the spatial-temporal evolution of the AEJ and AEWs; and improving forecasts of the dust-modified AEJ-AEW system and its possible effects on tropical cyclogenesis over the Atlantic Ocean.Broader Impacts:The broader impacts of this work includes: advancing knowledge on the sensitivity of AEJ-AEW system to the dust plume properties (e.g., location, concentration, spatial gradients), which could aid in the prediction of AEWs and thus tropical cyclones; demonstrating the importance of dust radiative heating on AEWs, which could motivate future studies to examine dust radiative effects on other synoptic scale disturbances that are associated with the dust source regions around the world.

夏季，北非上北非的大气循环的特征是三个惊人的特征：非洲东方喷气式飞机（AEJ）；非洲东方波浪（AEWS）；和大量的撒哈拉矿物粉尘气溶胶。这项研究的核心目的是确定撒哈拉粉尘对AEJ-AEW系统线性动力学和非线性演化的影响。为了实现这一目标，将执行几项以回答以下问题的任务：除尘性的加热是否能使原本稳定的AEJ（反之亦然）不稳定？如果是这样，灰尘浓度，空间梯度，排放变异性等哪个方面会影响AEJ的线性稳定性？灰尘物理学如何以AEJ的空间结构和能量学表现？是否有特定的位置和灰尘浓度和分布的组合可以优化AEWS的线性生长（或衰减）？随着AEWS成长为有限的振幅，灰尘如何影响其结构？是否有特定的位置和灰尘浓度和分布的组合可以优化AEWS的发展？ AEJ-AEW系统如何响应一个变化的灰尘羽流，该系统会定期或情节地变化？回答这些问题，而其他问题，以及其他，天气研究和预测（WRF）模型，该模型将与尘埃示踪模型相结合，可用于运行和无粉尘的系统实验序列。将使用标准方法分析模拟的数据并比较。分析将提供有关灰尘对以下影响的影响：AEWS的增长率，繁殖和结构；临界层的形成，这些层已显示在热带环生成中起作用；以及AEJ-AEW系统的本地和全球能量学。智能优点：研究的智力优点包括：促进了解撒哈拉尘埃反馈如何依赖于粉尘浓度及其空间分布的组合，影响AEWS的线性增长和非线性发展；对撒哈拉矿物粉尘的时空变异性与AEJ和AEWS的时空演化之间的关系发展洞察力； and improving forecasts of the dust-modified AEJ-AEW system and its possible effects on tropical cyclogenesis over the Atlantic Ocean.Broader Impacts:The broader impacts of this work includes: advancing knowledge on the sensitivity of AEJ-AEW system to the dust plume properties (e.g., location, concentration, spatial gradients), which could aid in the prediction of AEWs and thus tropical cyclones;证明尘埃辐射加热对AEW的重要性，这可能激发未来的研究，以检查与世界各地尘埃源区域相关的其他概要尺度干扰的尘埃辐射影响。