Understanding the Formation and Impacts of Warm-Season Trans-Atlantic African Dust Extremes

矿物粉尘是由强风从干燥和稀疏的植被覆盖的陆地表面散发出来的。在大气中，尘埃颗粒改变辐射收支(通过吸收、散射和发射)，并与云相互作用，影响广泛的大气过程。每年，大量的非洲尘埃被输送到热带大西洋。向西的传输路径受大气环流的调节，并在北半球夏季达到最大北向位置，此时炎热、干燥的撒哈拉尘埃羽流经常穿过热带北大西洋漂移到加勒比海盆地和美国。据报道，在一些非洲沙尘暴发期间，热带北大西洋上空的沙尘载量极高，同时波多黎各和美国南部的地面沙尘浓度较高，大大恶化了这些顺风地区的空气质量。虽然在表征跨大西洋非洲尘埃羽流方面取得了重大进展，但暖季极端跨大西洋尘埃事件的原因和影响还不完全清楚。例如，目前尚不清楚为什么北非沙尘排放的增加导致热带大西洋上某些年份的沙尘载量极高，而另一些年份则不是。该项目将使用卫星产品、地面观测和再分析来确定造成跨大西洋极端沙尘事件的大气环流和陆地表面过程，并研究极端沙尘羽流如何影响其向西输送路径的能量平衡、云和空气质量。将利用区域化学模式在观测和数值实验中审查尘埃排放和输送在形成极端横跨大西洋的非洲尘埃羽流中的相对作用。拟议的工作包括对本科生和研究生进行科学培训，并通过堪萨斯大学自然历史博物馆举办的外联活动开展教育活动。北非是全球主要的大气气溶胶来源。对跨大西洋非洲极端沙尘事件的可变性、原因和影响的先进知识将有助于更好地了解气溶胶在气候系统中的作用，这是评估当前和预测未来气候变化的主要不确定性来源之一。这些发现将有助于未来对横贯大陆的沙尘事件和美国空气污染预测的研究。该项目将通过吸引本科生参与该项目，并将研究活动和成果纳入本科生和研究生课程，将研究与教育相结合。该项目将支持一名研究生和两名本科生培养下一代气候和大气科学家。此外，研究人员将参加由堪萨斯大学自然历史博物馆举办的外展活动，与公众分享研究结果。该项目由大气和地球空间科学部(AGS)的气候与大尺度动力学(CLD)和物理与动力气象学(PDM)计划以及既定的激励竞争研究计划(EPSCoR)联合资助。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。

Mineral dust is emitted from dry and sparsely vegetated land surface by strong winds. In the atmosphere, dust particles modify radiation budget (via absorption, scattering, and emission) and interact with clouds, affecting a wide range of atmospheric processes. Each year a large amount of African dust is transported toward the tropical Atlantic Ocean. The westward transport pathway is regulated by atmospheric circulations and reaches its maximum northward position in boreal summer, when the hot, dry Saharan dust plumes often drift across the tropical North Atlantic into the Caribbean Basin and the United States. Extremely high dust loadings over the tropical North Atlantic are reported during some African dust outbreaks, along with high surface concentrations of dust over Puerto Rico and the southern United States that greatly degraded air quality in these downwind regions. While significant progress has been made toward characterizing trans-Atlantic African dust plumes, the causes and impacts of warm season extreme trans-Atlantic dust events are not fully understood. For instance, it is not clear why enhanced dust emissions in North Africa resulted in extremely high dust loading over the tropical Atlantic in some years but not others. This project will use satellite products, ground observations, and reanalysis to identify atmospheric circulation and land surface processes that are responsible for the extreme trans-Atlantic dust events and to examine how extreme dust plumes affect energy balance, clouds, and air quality along their westward transport pathway. The relative roles of dust emissions and transport in the formation of extreme trans-Atlantic African dust plumes will be examined in both observations and numerical experiments using a regional chemistry model. The proposed work includes scientific training for undergraduate and graduate students and educational activities through outreach events held by the University of Kansas Natural History Museum.North Africa is a prominent global source of atmospheric aerosols. Advanced knowledge of the variability, causes, and impacts of extreme trans-Atlantic African dust events will allow better understanding of the role of aerosols in the climate system, which is one of the major sources of uncertainty in evaluating current and predicting future climate change. The findings will benefit future studies of trans-continental dust events and air pollution forecast in the United States. The project will integrate research with education by engaging undergraduate students into the project and by incorporating research activities and findings into undergraduate and graduate courses. The project will support one graduate student and two undergraduate students to train the next generation of climate and atmospheric scientists. In addition, the investigators will participate in outreach events held by the University of Kansas Natural History Museum to share the findings with the public.This project is jointly funded by the Climate and Large-Scale Dynamics (CLD) and Physical and Dynamic Meteorology (PDM) programs in Division of Atmospheric and Geospace Sciences (AGS) as well as the Established Program to Stimulate Competitive Research (EPSCoR).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.