Improved representation of the global dust cycle using observational constraints on dust properties and abundance

Abstract

Abstract. Even though desert dust is the most abundant aerosol by mass in Earth's atmosphere, atmospheric models struggle to accurately represent its spatial and temporal distribution. These model errors are partially caused by fundamental difficulties in simulating dust emission in coarse-resolution models and in accurately representing dust microphysical properties. Here we mitigate these problems by developing a new methodology that yields an improved representation of the global dust cycle. We present an analytical framework that uses inverse modeling to integrate an ensemble of global model simulations with observational constraints on the dust size distribution, extinction efficiency, and regional dust aerosol optical depth. We then compare the inverse model results against independent measurements of dust surface concentration and deposition flux and find that errors are reduced by approximately a factor of two relative to current model simulations of the Northern Hemisphere dust cycle. The inverse model results show smaller improvements in the less dusty Southern Hemisphere, most likely because both the model simulations and the observational constraints used in the inverse model are less accurate. On a global basis, we find that the emission flux of dust with geometric diameter up to 20 μm (PM20) is approximately 5,000 Tg/year, which is greater than most models account for. This larger PM20 dust flux is needed to match observational constraints showing a large atmospheric loading of coarse dust. We obtain gridded data sets of dust emission, vertically integrated loading, dust aerosol optical depth, (surface) concentration, and wet and dry deposition fluxes that are resolved by season and particle size. As our results indicate that this data set is more accurate than current model simulations and the MERRA-2 dust reanalysis product, it can be used to improve quantifications of dust impacts on the Earth system.

Two mega sand and dust storm events over northern China in March 2021: transport processes, historical ranking and meteorological drivers

“…Currently, models still face huge challenges in accurately quantifying dust emissions, due to limitations such as uncertainties in the dust source locations and dust emission parameterization schemes (Kok et al, 2020). Aerosol reanalysis involving the assimilation of a large number of observations is considered a valuable tool for evaluating dust processes in climate models (Wu et al, 2020;Zhao et al, 2021).…”

Linking the Different Diameter Types of Aspherical Desert Dust Indicates That Models Underestimate Coarse Dust Emission

“…Desert dust is a key atmospheric component that produces important effects on the Earth system, including by affecting the radiation budget (Kok et al., 2020, 2021; Pérez et al., 2006), cloud microphysics (DeMott et al., 2015), atmospheric chemistry (Tang et al., 2016), and biogeochemical cycles (Ito, Myriokefalitakis, et al., 2019). Furthermore, dust aerosols produce risks to human health (Giannadaki et al., 2014; Huang, Kok, Martin, et al., 2019).…”

Seasonality in Saharan Dust Across the Atlantic Ocean: From Atmospheric Transport to Seafloor Deposition

“…It is a unique combination of extensive spatial coverage from source to sink, as well as a continuous record over multiple years. This continuous data set of dust concentration, dust deposition fluxes and grain size along a transect in the remote open ocean will be useful for validating and constraining model simulations with various complexity, from fully coupled Earth system models (Kok et al., 2020) to simple deposition‐enabled trajectory models (Y. Yu et al., 2020).…”