New Study Analyzes African Dust Crossing Atlantic Ocean
UM Rosenstiel School research team’s analysis will help improve weather and climate forecasts
July 07, 2016
Composite image from Suomi National Polar-orbiting Partnership (NPP) satellite Visible Infrared Radiometer Suite (VIIRS). (Click here for larger image)
Credit: Norman Kuring, NASA Goddard Space Flight Center/Suomi NPP.
MIAMI—Summer isn’t just hurricane season in Florida, it’s also dust season. And the two have a few things in common.
Scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science are taking advantage of this year’s dust season to study the aging of these aerosol particles that travel across the Atlantic Ocean from Africa to Florida. The study will take place from 1 July to 31 August and will help improve weather and climate forecasts, including our understanding of the early development of tropical storms.
UM Rosenstiel School Professor Emeritus Joseph Prospero and will coordinate his studies with those of colleagues at Izaña Observatory located on a 8,000-foot (2,390-meter) mountain on Tenerife in the Canary Islands, 300 km from the coast of West Africa. The Izaña team will study dust as it emerges from Africa and the Miami scientists will make an identical set of measurements on the island of Barbados in the Caribbean, and in Miami as the same dusty air mass passes over these sites about a week later.
“By making coordinated measurements at Izaña Observatory in the eastern Atlantic and again at Barbados and Miami in the western Atlantic, we can develop a detailed picture of the properties of African dust and its impact on the atmospheric and ocean environment in this huge region,” said Prospero, who is known as the “grandfather of dust” for his pioneer research on African dust that began in 1965.
The researchers will look for changes in the size and chemical composition of the dust as it travels across the Atlantic Ocean. These data will be incorporated in weather and climate models to see how well the models can simulate the processes of dust generation and transport, and its effect on the environment.
African dust is carried in the Saharan air layer (SAL), a layer of hot, dry air that extends from about 3,280 feet (1,000 meters) to 3.7 miles (6 kilometers) in altitude and originates in the Saharan Desert. This dust is a major nutrient source in the tropical Atlantic Ocean, and plays an important role in the biological productivity of Atlantic and Caribbean ocean waters.
Of particular interest to the researchers is the role of African dust plumes on the formation and properties of tropical storms. The SAL moves west over the Atlantic in association with easterly waves, an area of relatively low air pressure associated with the development of tropical disturbances, some of which evolve into tropical storms. Scientists have estimated that nearly 85 percent of major hurricanes originate from easterly waves and that the SAL can suppress the development of hurricanes in the Atlantic.
The study is focusing on the changes in the SAL and the associated dust as it crosses the Atlantic since these changes can affect the level of impact that the dust has on meteorological processes.
“By developing a better understanding of the variability of dust storms and the properties of the transported dust, we can develop better hurricane and climate models,” said Prospero. “It will help us to anticipate how dust transport will change as our climate changes, which may have a huge impact on the climate in North Africa.”
Saharan dust also affects the quality of the air we breathe since the air contains high concentrations of particulate matter. For this reason, the U.S. Environmental Protection Agency and the World Health Organization (WHO) have set limits on the concentration of suspended particles in the air. During the summer months, African dust is the dominant particulate species in the atmosphere over the Caribbean Basin and Florida. During summer across this wide region, the concentration of dust often exceeds WHO guidelines.
“In our study we eventually hope to be able to predict the occurrence of major dust outbreaks over the Caribbean Basin and the southern U.S. This would enable us to issue health alerts to susceptible populations, such as those with impaired respiratory systems, the elderly and infants,” said Prospero.
The ongoing study is supported by grants from the National Science Foundation and NASA. UM Rosentiel School scientists Paquita Zuidema and Cassandra Gaston are also involved in the study.
About the University of Miami’s Rosenstiel School
The University of Miami is one of the largest private research institutions in the southeastern United States. The University’s mission is to provide quality education, attract and retain outstanding students, support the faculty and their research, and build an endowment for University initiatives. Founded in the 1940’s, the Rosenstiel School of Marine & Atmospheric Science has grown into one of the world’s premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. For more information, visit: www.rsmas.miami.edu and Twitter. Visit the University of Miami’s report on climate change www.climate.miami.edu