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Abstract. Nitrate (NO3-) aerosol is projected to increase dramatically in the coming decades and may become the dominant inorganic particle species. This is due to the continued strong decrease in SO2 emissions, which is not accompanied by a corresponding decrease in NOx and especially NH3 emissions. Thus, the radiative effect (RE) of NO3- aerosol may become more important than that of SO42- aerosol in the future. The physicochemical interactions of mineral dust particles with gas and aerosol tracers play an important role in influencing the overall RE of dust and non-dust aerosols but can be a major source of uncertainty due to their lack of representation in many global climate models. Therefore, this study investigates how and to what extent dust affects the current global NO3- aerosol radiative effect through both radiation (REari) and cloud interactions (REaci) at the top of the atmosphere (TOA). For this purpose, multiyear simulations nudged towards the observed atmospheric circulation were performed with the global atmospheric chemistry and climate model EMAC, while the thermodynamics of the interactions between inorganic aerosols and mineral dust were simulated with the thermodynamic equilibrium model ISORROPIA-lite. The emission flux of the mineral cations Na+, Ca2+, K+, and Mg2+ is calculated as a fraction of the total aeolian dust emission based on the unique chemical composition of the major deserts worldwide. Our results reveal positive and negative shortwave and longwave radiative effects in different regions of the world via aerosol–radiation interactions and cloud adjustments. Overall, the NO3- aerosol direct effect contributes a global cooling of −0.11 W m−2, driven by fine-mode particle cooling at short wavelengths. Regarding the indirect effect, it is noteworthy that NO3- aerosol exerts a global mean warming of +0.17 W m−2. While the presence of NO3- aerosol enhances the ability of mineral dust particles to act as cloud condensation nuclei (CCN), it simultaneously inhibits the formation of cloud droplets from the smaller anthropogenic particles. This is due to the coagulation of fine anthropogenic CCN particles with the larger nitrate-coated mineral dust particles, which leads to a reduction in total aerosol number concentration. This mechanism results in an overall reduced cloud albedo effect and is thus attributed as warming.
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This content will become publicly available on January 16, 2026
The Hawaii Dust Regime: Patterns and Variability in Aerosol Mineral Dust From MERRA‐2 at Station ALOHA and the Hawaii Aerosol Time‐Series
The transport and delivery of low‐abundance, bioactive trace elements to the surface ocean by aerosol mineral dust is a major planetary control over marine primary production and hence the global carbon cycle. Variations in the concentration of atmospheric dust have established links to global climate over geologic timescales and to regional biogeographic shifts over seasonal timescales. Constraining atmospheric dust variability is thus of high value to understanding oceanographic systems, especially vast, constitutively low‐nutrient subtropical gyre ecosystems and high‐nutrient/low‐chlorophyll ecosystems where availability of the trace element iron is a dominant ecological control. Here we leverage the MERRA‐2 reanalysis product to examine over four decades of surface‐level atmospheric mineral dust concentrations in a domain of the subtropical North Pacific centered at Ocean Station ALOHA. This study region has been sampled regularly since the mid‐1980s and was the site of the Hawaii Aerosol Time‐Series (HATS) project in 2022–2023. Two unequal semi‐annual periods of elevated dust evident in the long‐term results are described and constrained. We look for evidence of shifts in total and seasonal atmospheric dust abundances or in the timing of the onset of the dominant spring/summer dusty period, finding year‐to‐year variations but little evidence for long‐term trends. We observe significant but complex relationships between the Pacific Decadal Oscillation (PDO) index and both dust and precipitation. The 2022 calendar year was among the dustiest years for the study domain in the preceding two decades and, by contrast, 2023 exhibited a significant early spring lull in dust.
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- PAR ID:
- 10588877
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 130
- Issue:
- 1
- ISSN:
- 2169-897X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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