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Influence of High-latitude Dust on Aerosol Radiative Effects and Deposition in the DOE Earth System Model

Presentation Date
Wednesday, December 15, 2021 at 7:55am - Wednesday, December 15, 2021 at 8:01am



Recent studies suggest that high-latitude dust sources play an important role in the Earth System, especially through the influence on glaciation of Arctic low-level clouds, snow albedo, and iron supply to the ocean and snow/ice biogeochemistry. Although the physical processes controlling dust emissions in high latitudes are similar to temperate regions, there are additional processes specific to cold regions such as soil properties, strong winds, permafrost, glacial retreat, and snow-melt processes all of which can affect the efficiency of dust emissions, its physicochemical properties, and distribution of aerosol deposition. There is currently lack of efforts to quantify the characteristics and climate impact of high-latitude dust represented in the Earth System models.

In the present study, a physically based vertical flux theory (Kok et al., 2014) is implemented to the DOE Earth System Model (E3SM) for dust generation. It calculates the time-dependent soil erodibility interactively based on the model-predicted soil moisture and fractional areas of bare ground (no vegetation or snow cover), enabling the coupling of dust emission with land surface changes within high latitudes. In the high latitudes (> 60ºN or 40ºS), there are evident increases of dust emissions. Annual emissions of the high-latitude dust with the new method contribute to about 1~2% of the global dust total under present-day condition, which is consistent with observationally based estimates. The high-latitude dusts peak in both winter and summer-to-fall months in the Arctic but only appear to be a large source in the Southern Hemisphere during Austral summer. The winter Arctic dust is driven by the high winds associated with the sub-arctic low, while summertime high-latitude dust particles in both hemispheres are emitted from ice-free land surfaces. The local dust sources are shown to provide an important source of ice-nucleating particles and nutrient iron supply in summer when the long-range transport of aerosols from the mid-latitudes is limited. The E3SM dust simulations are compared with the long-term surface measurements at the DOE/ARM Barrow site in Alaska and the shipboard measurements of dust deposition fluxes in the high latitudes as well as the CESM2 model results. The contribution of high-latitude dust to the surface and top of the atmosphere energy balance will also be presented.

Funding Program Area(s)