Modeling dust and soluble iron deposition to the South Atlantic Ocean

• Published in: Journal of Geophysical Research
• Main Authors: M.S., Johnson, N., Meskidze, F., Solmon, S., Gasso, P.Y., Chuang, D.M., Gaiero, R.M., Yantosca, S., Wu, Y., Wang, C., Carouge
• Other Authors: Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: dust; soluble iron; Patagonia; [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; South Atlantic Ocean
• Online Access: https://hal.science/hal-00993293; https://hal.science/hal-00993293/document; https://hal.science/hal-00993293/file/Journal%20of%20Geophysical%20Research%20Atmospheres%20-%202010%20-%20Johnson%20-%20Modeling%20dust%20and%20soluble%20iron%20deposition%20to%20the%20South.pdf; https://doi.org/10.1029/2009JD013311

International audience The global chemical transport model GEOS-Chem, implemented with a dust-iron dissolution scheme, was used to analyze the magnitude and spatial distribution of mineral dust and soluble-iron (sol-Fe) deposition to the South Atlantic Ocean (SAO). The comparison of model results with remotely sensed data shows that GEOS-Chem can capture dust source regions in Patagonia and characterize the temporal variability of dust outflow. For a year-long model simulation, 22 Tg of mineral dust and 4 Gg of sol-Fe were deposited to the surface waters of the entire SAO region, with roughly 30% of this dust and sol-Fe predicted to be deposited to possible high nitrate low chlorophyll oceanic regions. Model-predicted dissolved iron fraction of mineral dust over the SAO was small, on average only accounting for 0.57% of total iron. Simulations suggest that the primary reason for such a small fraction of sol-Fe is the low ambient concentrations of acidic trace gases available for mixing with dust plumes. Overall, the amount of acid added to the deliquesced aerosol solution was not enough to overcome the alkalinity buffer of Patagonian dust and initiate considerable acid dissolution of mineral-iron. Sensitivity studies show that the amount of sol-Fe deposited to the SAO was largely controlled by the initial amount of sol-Fe at the source region, with limited contribution from the spatial variability of Patagonian-desert topsoil mineralogy and natural sources of acidic trace gases. Simulations suggest that Patagonian dust should have a minor effect on biological productivity in the SAO.