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

University Of Kansas Center For Research Inc, Lawrence KS

Investigators

Abstract

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.