Coupled Model Inter-comparison Project Phase-5 Weather Research and Forecasting (CMIP5-WRF) Simulations Quantifying Anthropogenic Forcing and Saharan Long-range Dust Transport

该奖项全部或部分由2021年美国救援计划法案（公法117-2）资助。卫星图像有时显示从西非到加勒比海的大西洋上覆盖着巨大的棕色空气尘埃羽。 从撒哈拉沙漠吹来的尘埃羽流，顺风吹了数千英里，其范围和厚度足以通过其辐射效应影响世界气候，并且足够的尘埃穿越大西洋影响加勒比海和美国东南部的空气质量。在当地，灰尘是整个北非和西非的公共卫生挑战，与哮喘，支气管炎，急性呼吸道感染和其他疾病有关。 撒哈拉沙尘的重大影响促使人们研究全球气候变化对沙尘排放和输送的可能影响，本项目利用一个区域模式-天气研究和预报模式，以及戈达德化学气溶胶辐射和输送模式中的沙尘模块-的计算机模拟，考虑了撒哈拉沙尘排放和输送在21世纪可能发生的变化。 利用全球再分析产品和未来气候变化全球模式模拟的边界条件，将WRF集成到西非和下风向大西洋。全球模式模拟取自耦合模式相互比较项目第5版的档案，使用三种不同的温室气体未来可能排放量估计数，工作重点是大气环流的变化及其对撒哈拉沙尘的飘移和迁移可能产生的影响。 这项工作的动机来自撒哈拉沙尘和北大西洋涛动（NAO）之间的联系，北大西洋涛动是冰岛低压和亚速尔群岛高压之间海平面压力的大规模振荡，导致赤道以北大西洋表面风强度的变化。 另一个考虑因素是，在气候变暖的情况下，撒哈拉热低压的加剧在多大程度上可能导致地面风的加强，这反过来又可能激起更多的沙漠灰尘。 热带辐合带（ITCZ）变暖引起的变化也被视为对撒哈拉沙尘穿越萨赫勒地区并进入几内亚地区的潜在影响。撒哈拉沙尘对健康的影响使该项目具有社会相关性和科学意义。 这里的一个考虑是，西非目前约有3.5亿人，预计到2050年人口将增加一倍以上。 另一个原因是，大西洋上空空气中尘埃含量的变化对美国的空气质量和登陆飓风的形成都有影响。 此外，该项目将为一名博士后研究员和一名研究生以及一名按小时工作的本科生提供支助和培训。 项目参与者参加校园环境导师计划，为高中生在学年期间开展项目。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Satellite images sometimes show a great brown plume of airborne dust covering the Atlantic ocean from West Africa to the Caribbean. The dust plume, lofted from the Sahara desert and blown downwind for thousands of miles, is extensive and thick enough to affect world climate through its radiative effects, and enough dust crosses the Atlantic to affect air quality in the Carribean and the southeast US. More locally, the dust is a public health challenge throughout North and West Africa, linked to asthma, bronchitis, acute respiratory infections, and other conditions. The substantial impacts of Saharan dust motivate research on the likely changes in dust emission and transport due to global climate change.This project considers likely changes in Saharan dust emission and transport over the 21st century using computer simulations from a regional model, the Weather Research and Forecasting (WRF) model with the dust module from the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. WRF is integrated over West Africa and the downwind Atlantic using boundary conditions from global reanalysis products and global model simulations of future climate change. Global model simulations are taken from the archive of the Coupled Model Intercomparison Project version 5 (CMIP5) and use three different estimates of likely future emissions of greenhouse gases.The work focuses on changes in atmospheric circulation and their likely effects on the lofting and transport of Saharan dust. Motivation for the work comes from the association between Saharan dust and the North Atlantic Oscillation (NAO), a large-scale oscillation in sea level pressure between the Icelandic Low and the Azores High that causes changes in the strength of the surface winds over the Atlantic north of the equator. A further consideration is the extent to which intensification of the Saharan Heat Low in a warming climate could cause strengthening of surface winds which could in turn stir up more dust from the desert. Warming-induced changes in the intertropical convergence zone (ITCZ) are also examined as a potential influence on Saharan dust transport across the Sahel and into the Guinea region.The health impacts of Saharan dust make the project societally relevant as well as scientifically interesting. One consideration here is that West Africa is currently home to roughly 350 million people and the population is expected to more than double by 2050. Another is that changes in the dust content of air over the Atlantic has implications for both US air quality and the formation of landfalling hurricanes. In addition, the project would provide support and training to a postdoctoral fellow and a graduate student, as well as an undergraduate student working on an hourly basis. Project participants participate in the campus EnvironMentors program, developing a project for a high school student to work on during the academic school year.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.