Grid-independent high-resolution dust emissions (v1.0) for chemical transport models: application to GEOS-Chem (12.5.0)

Abstract

Abstract. The nonlinear dependence of the dust saltation process on wind speed poses a challenge for models of varying resolutions. This challenge is of particular relevance for the next generation of chemical transport models with nimble capability for multiple resolutions. We develop and apply a method to harmonize dust emissions across simulations of different resolutions by generating offline grid-independent dust emissions driven by native high-resolution meteorological fields. We implement into the GEOS-Chem chemical transport model a high-resolution dust source function to generate updated offline dust emissions. These updated offline dust emissions based on high-resolution meteorological fields strengthen dust emissions over relatively weak dust source regions, such as in southern South America, southern Africa and the southwestern United States. Identification of an appropriate dust emission strength is facilitated by the resolution independence of offline emissions. We find that the performance of simulated aerosol optical depth (AOD) versus measurements from the AERONET network and satellite remote sensing improves significantly when using the updated offline dust emissions with the total global annual dust emission strength of 2000 Tg yr−1 rather than the standard online emissions in GEOS-Chem. The updated simulation also better represents in situ measurements from a global climatology. The offline high-resolution dust emissions are easily implemented in chemical transport models. The source code and global offline high-resolution dust emission inventory are publicly available.

Ice nucleating properties of airborne dust from an actively retreating glacier in Yukon, Canada

“…The atmosphere was resolved using 47 vertical layers from the surface to 0.01 hPa (about 100 m thick near the surface). We used the offline desert dust emissions described by Meng et al , 50 which were in turn based on the Mineral Dust Entrainment and Deposition (DEAD) emissions scheme. 51 Notably, no natural high latitude dust emissions were included in the model.…”

Improved Parameterization for the Size Distribution of Emitted Dust Aerosols Reduces Model Underestimation of Super Coarse Dust

“…Mineral dust is an important component of the Earth system, impacting Earth's radiation budget, clouds, precipitation, biogeochemistry, and air quality (Balkanski et al., 2021 ; Chen et al., 2019 ; Guieu et al., 2019 ; Jickells et al., 2005 ; Kosmopoulos et al., 2017 ; Meng et al., 2021 ). Because all these impacts depend sensitively on dust size (Mahowald et al., 2014 ), global aerosol models need to accurately represent the dust particle size distribution (PSD) to quantify the various dust impacts on the Earth system.…”

Weaknesses in dust emission modelling hidden by tuning to dust in the atmosphere

“…Commonly, aerosol optical depth (AOD) from point (ground-based) or large area Earth observation (EO) data are used to evaluate the performance and / or calibrate dust emission model simulations (Meng et al, 2021). This approach assumes that: i) dust in the atmosphere represents the dust emission process, and ii) the spatial variation in magnitude and frequency of dust emission in the model is correct.…”