Simulated marine cloud brightening poses a low risk of precipitation changes in north-eastern Australia
Matt Woodhouse (originally submitted by Rebecca Jackson)
Regional marine sky and cloud brightening (MCB) has the potential to alleviate coral bleaching in the Great Barrier Reef (GBR) through reduced light and temperature during summer. MCB involves injecting sea spray aerosol into the lower atmosphere to enhance aerosol direct and cloud albedo effects. However, any change to aerosol and cloud droplet distribution has the potential to also affect precipitation. In this study, we explore the risk of precipitation changes over north-eastern Australia due to a range of sea spray aerosol injection scenarios. The scenarios were simulated using the Unified Model Regional Nesting Suite with aerosol and cloud microphysics, set up over the GBR and north-eastern Australia (called ACCESS-GBR). Our results showed no significant impact on precipitation during the 2022 summer, even in response to unrealistically large aerosol injections. Simulated changes were small (<4%) and negligible in comparison to the natural precipitation range in the region. Further work is needed to assess risk during other time periods and in response to other injection scenarios. However, our preliminary findings indicate that MCB over the GBR poses a low risk to precipitation and that any potential risk is likely to be further reduced in more realistic, deployment-scale scenarios.
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