Abstract View
A Global-scale Mineral Dust Equation
XUAN LIU, Jay R. Turner, Randall Martin, Bret Schichtel, Jenny Hand, Washington University in St. Louis
Abstract Number: 535
Working Group: Remote and Regional Atmospheric Aerosol
Abstract
A robust method to estimate mineral dust mass in ambient particulate matter (PM) is essential, as the dust fraction cannot be directly measured but is needed to understand dust impacts on the environment and human health. In this study, a global-scale dust equation is developed that builds on the widely used Interagency Monitoring of Protected Visual Environments (IMPROVE) network’s “soil” formula that is based on five measured elements (Al, Si, Ca, Fe, and Ti). We incorporate K, Mg, and Na into the equation using the mineral-to-aluminum (MAL) mass ratio of (K2O+MgO+Na2O)/Al2O3 and apply a correction factor (CF) to account for other missing compounds and adsorbed water, based on which we develop a global-scale dust equation with region-specific coefficients (Dust = [1.89Al×(1+MAL)+2.14Si+1.40Ca+1.36Fe+1.67Ti]×CF). For desert dust in major global source regions, the estimates from the global equation are consistent with the total mineral mass (calculated by summing all the oxides of dust) with a small normalized mean bias (NMB within ±1%). For PM2.5 with high dust content from the U.S. IMPROVE Network, the global equation estimates the dust mass well (NMB within ±5%) at most sites. For desert dust transported to non-source regions, the global equation still performs well (NMB within ±2%). The global equation can also represent paved road, unpaved road, and agricultural soil dust well (NMB within ±5%). This global-scale dust equation provides a promising approach for characterizing mineral dust of different types from various regions.