A03: Dust Life Cycle in E3SMv3

Impact of Improved Dust Life Cycle on Radiation and Nutrient Deposition in E3SMv3

• Yan Feng

• yfeng@anl.gov

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‘Atmosphere'

E3SM

Quantification of dust life cycle and radiative effects in Earth System Models has important implications for improving the model's capabilities to simulate water cycle and biogeochemistry in response to climate change. In E3SMv3, we implemented a physically based vertical flux theory for dust generation. It calculates the time-dependent soil erodibility interactively, enabling a close coupling of dust generation with land surface changes. As a result, E3SMv3 captures the observed spatial and temporal variations in dust and agrees better with the long-term aerosol surface measurements, compared to E3SMv2. Constrained by a global dust optical depth of 0.03, the annual mean dust burden (2005-2014) in E3SMv3 is 32 Tg, within the range of the CMIP6 multi-model estimates (9-74 Tg). The simulated global dust lifetime (3 days) is now comparable to the multi-model mean of 3.5 days due to an improved coupling of aerosol processes (Wan et al., 2023), which enhances the vertical and long-range transport of dust in E3SMv3. The new dust emission scheme also predicts high-latitude dust (HLD) sources from the snow-free regions, which add up to about 3% to global dust emissions. 10-year simulations suggest that radiative feedback of HLD could perturb the annual mean surface temperature in polar regions (>60° N or S) up to ±0.5 K. HLD and enhanced dust transport also increase dust deposition fluxes significantly within high latitudes, enhancing the iron nutrient supply to the ocean and darkening the snow/ice surfaces. The overall impact on the shortwave (SW) cooling and longwave (LW) warming of dust simulated by E3SMv3 will be presented.

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