5:15 PM - 7:15 PM
[ACG42-P04] Evaluation of anthropogenic and lithogenic aerosols predicted by IMPACT model based on observations of trace metals in aerosols
Keywords:water-soluble iron, anthropogenic aerosol, mineral dust, air pollution
Atmospheric depositions of bioaccessible iron (Fe) from anthropogenic (fuel combustion and metal production), lithogenic (wind-blown dust), and pyrogenic (open biomass burning and pyro-convective dust) aerosols represent important external sources of micronutrients to the open ocean, which could affect marine ecosystems and climate through marine biogeochemical feedbacks. However, significant uncertainties remain in the source apportionment, due to a lack of source-specific evaluation of Fe-laden aerosols. In this presentation, we evaluate the source contributions predicted by numerical models using aerosol and seawater filtration samples collected during research cruises in the North Pacific region. Particularly, we focus on trace metals (Fe, Al, Ti, V, Mn, Cu, Zn, Pb) and dust (quartz) in aerosols.
The IMPACT model was used as the atmospheric chemical transport model. Anthropogenic/pyrogenic particles emissions were prescribed at emission, whereas lithogenic emissions were dynamically simulated. Observations of aerosols and seawater filtration samples collected during research cruises in the North Pacific region were used in the analysis to evaluate the numerical model. Observational data compiled by previous studies were also used.
The IMPACT model showed better agreement with the dust deposition flux estimated based on individual quartz particle observations in the North Pacific than the MERRA2 data. The IMPACT model also reproduced well the observed quartz content of coarse particles over the North Pacific Ocean. The IMPACT model reproduced well the concentration of soluble iron concentration in bulk samples. However, the model underestimated total Fe concentration for coarse particles. Thus, the compensation by overestimates in Fe solubilities led to the good agreement of soluble Fe concentrations. The results indicate that the improvement in emission rates alone would result in worse predictability of the model for soluble iron concentrations. We will discuss the source apportionment with Fe isotope analysis.
The IMPACT model was used as the atmospheric chemical transport model. Anthropogenic/pyrogenic particles emissions were prescribed at emission, whereas lithogenic emissions were dynamically simulated. Observations of aerosols and seawater filtration samples collected during research cruises in the North Pacific region were used in the analysis to evaluate the numerical model. Observational data compiled by previous studies were also used.
The IMPACT model showed better agreement with the dust deposition flux estimated based on individual quartz particle observations in the North Pacific than the MERRA2 data. The IMPACT model also reproduced well the observed quartz content of coarse particles over the North Pacific Ocean. The IMPACT model reproduced well the concentration of soluble iron concentration in bulk samples. However, the model underestimated total Fe concentration for coarse particles. Thus, the compensation by overestimates in Fe solubilities led to the good agreement of soluble Fe concentrations. The results indicate that the improvement in emission rates alone would result in worse predictability of the model for soluble iron concentrations. We will discuss the source apportionment with Fe isotope analysis.