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植被稀疏的陆地表面散发出来的。在大气中，尘埃粒子改变辐射收支（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。每年都有大量的非洲尘埃被输送到热带大西洋。向西的输送路径受大气环流的调节，在北方夏季达到最大向北的位置，此时炎热干燥的撒哈拉尘羽往往漂过热带北大西洋进入加勒比海盆地和美国。 据报告，在非洲一些沙尘暴爆发期间，热带北大西洋上空的沙尘含量极高，沿着波多黎各和美国南部上空的沙尘表面浓度很高，大大降低了这些顺风地区的空气质量。虽然在描述跨大西洋非洲沙尘羽流方面取得了重大进展，但暖季极端跨大西洋沙尘事件的原因和影响尚未完全了解。例如，目前尚不清楚为什么北非的粉尘排放量增加导致热带大西洋上空的粉尘含量在某些年份极高，而在其他年份却没有。该项目将利用卫星产品、地面观测和再分析来确定造成极端跨大西洋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能量平衡、云和沿着其向西输送路径的空气质量。将使用区域化学模型，通过观测和数值实验，研究尘埃排放和输送在形成极端的跨大西洋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。北非是全球大气气溶胶的一个突出来源。对跨大西洋非洲极端沙尘事件的变异性、原因和影响的深入了解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。这一发现将有利于美国未来跨大陆沙尘事件和空气污染预报的研究。该项目将把研究与教育结合起来，让本科生参与该项目，并将研究活动和研究结果纳入本科生和研究生课程。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，本发明还提供了一种方法，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的气候和大尺度动力学（CLD）、物理和动力气象学（PDM）项目以及刺激竞争性研究的既定项目（EPSCoR）共同资助该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.