A Saharan dust plume is continuing its journey from Africa, crossing the Caribbean and making its way into the Gulf Coast region in the coming days.
Natalie Mahowald, professor in the Department of Earth and Atmospheric Sciences at Cornell University and a fellow at the Cornell Atkinson Center for Sustainability, is working with NASA to study desert dust’s impact on the climate. She says that the dust plume threatens air quality in the southeastern U.S., but that it could lead to fewer hurricanes and enhanced CO2 uptake in the ocean.
“This huge North African dust plume crossing the Atlantic is causing substantial air quality problems across the Caribbean, and looks like it may well cause higher particulates in the atmosphere in the southeastern U.S. Previous studies of these types of events, for example one in 1999 from Joe Prospero at University of Miami, have shown that these events can be important for air quality, but are rarely considered.
“In addition, North African dust over the tropical North Atlantic blocks the incoming sunlight and tends to reduce the ocean temperature. This has a tendency to lead to fewer and weaker hurricanes, so that is good news for folks living in the tropics.
“Once the dust deposits onto the ocean, the dust can provide nutrients for ocean phytoplankton to have blooms, because the dust carries both phosphorus and iron. Ocean biota in the summer are often starving for both phosphorus and iron, and thus having this additional infusion of nutrients can enhance their growth, potentially enhancing CO2 uptake.
“But all these effects are very sensitive to the composition of the dust, which is poorly known. Our new NASA project: EMIT, is scheduled to build a new instrument to be put onto the space station in a couple years. This instrument is an imaging spectrometer, so it will look in fine detail in these source regions where the dust is coming from, using many different wavelengths, to deduce what the chemical composition of the source regions are. This will then provide information for our models, to tell us the chemical composition of the dust, so that we can better understand the impact of plumes like this on air quality, health, weather and biogeochemistry.”
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