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The calculated global and annual mean dust aerosol optical depth (AOD) is 0.026 and 0.03 in the low- (~1 degree) and high- (~0.25 degree) resolution E3SMv1, respectively. The model estimates of global dust AOD are similar independent of resolution, because dust emissions are tuned to match the observational constraint of global dust AOD at 0.03±0.01. There Yet, there are still substantial differences in the predicted dust AOD distributions depending on the model resolution, i.e., about 5 times different near differences over the Taklimakan desert. The changes in dust AOD are more than ±10% near the dust source regions or in the downwind resulting from local changes of dust emissions, dry and wet removal efficiencies. They could further affect the simulated regional energy balance, especially in the dust-influenced high latitudes where the climate sensitivity to dust forcing is large. Compared to the ground-based AERONET observations of AOD, the low-resolution E3SMv1 underpredicts the total AOD by about 31% averaged over the 247 AERONET sites. However, the underestimation of AOD is mainly due to aerosol predictions in Asia associated with the anthropogenic emissions (year 2000). Over the selected 14 ‘dusty’ AERONET sites, the modeled mean AOD (0.299) agrees well with the AERONET data (0.311), for a correlation coefficient of 0.91. The vertical distribution of dust is compared with the CALIPSO satellite-retrieved profiles, indicating an underestimation of dust vertical transport. This is related to the short lifetime of dust simulated by the E3SMv1 for less than 2 days, due to excessive dry and wet dust removals compared with other global climate models.
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