Modeling Dust and Dissolved Iron Deposition to the Southern Ocean

• Main Author: Johnson, Matthew Stephen
• Other Authors: Yang Zhang, Committee Member, David DeMaster, Committee Member, Nicholas Meskhidze, Committee Chair
• Language: unknown
• Published: 2010
• Subjects: acid mobilization; iron; Southern Ocean; dust; Patagonia; South Atlantic Ocean
• Online Access: http://www.lib.ncsu.edu/resolver/1840.16/6294

Aeolian dust deposition has proven to be a critical source of iron to the high nitrate low chlorophyll oceanic regions around the globe. This research was conducted to quantify mineral dust and dissolved iron fluxes to the Southern Atlantic sector of the Southern Ocean, which is postulated to be the largest oceanic region where marine productivity is limited by the micronutrient iron. To quantify mineral dust and dissolved iron fluxes the 3D global chemistry transport model GEOS-Chem, implemented with a prognostic iron dissolution scheme (GEOS-Chem/DFeS), was applied to the Patagonia and South Atlantic Ocean domain between October 2006 and September 2007. Our model simulations are focused on topics such as the model performance of Patagonian dust mobilization, transport, and deposition to the South Atlantic Ocean, mineral iron dissolution within advecting Patagonian dust and deposition of soluble iron to the surface waters of South Atlantic Ocean. Sensitivity simulations were conducted to estimate the magnitude and rates of dissolved/soluble iron deposited associated with natural sources of SO2 (volcanic emissions and oxidation of Dimethyl Sulfide) along with different mineralogical compositions of Patagonian soil. Daily, monthly, seasonally, and yearly averaged model outputs of mineral dust emissions, transport, and deposition with associated iron dissolution and deposition would be compared to past literature, Patagonian dust reports, MODIS real-time imagery, and MODIS AOD values to better understand the performance of GEOS-Chem/DFeS. GEOS-Chem deposited an annual magnitude of ~18 Tg of mineral dust to the South Atlantic Ocean during our yearlong simulation. This proved to fall within the range of annual dust deposition estimated by past modeling and measurement studies focused on our researched domain. The model also demonstrated the ability to capture dust advection and deposition seasonality, while being in compliance with climatic conditions favorable for dust emission and transport, in-situ mineral dust ...