Characterisation and dispersion of particle emissions for marine cloud brightening over the Great Barrier Reef (Citation and Abstract only)
Creators: name: Hernandez Jaramillo, Diana C.
Publisher: name: Southern Cross University
Year: 2024
Subjects: Marine cloud brightening
Plume dispersion
Airborne measurements
Solar radiation management

description: Rising sea surface temperatures increasingly threaten the Great Barrier Reef (GBR) by intensifying coral bleaching events. Marine cloud brightening (MCB), a solar radiation management technique, could help reduce the rate of heating of the sea surface by enhancing cloud reflectance. MCB consists of dispersing a plume of seawater droplets over the ocean. The evaporation of those droplets generates nano-sized sea-salt aerosol (SSA) that disperse through the atmosphere until some are incorporated into clouds. Previous literature has raised concerns regarding the potential adverse impact of droplet evaporation since it could produce a negatively buoyant plume hindering the ability of those particles to reach clouds, hence, reducing MCB’s effectiveness. Significant gaps were found in empirical data and theoretical models, emphasizing the necessity for field experiments to validate the MCB concept. This thesis aims to investigate the dispersion and evolution of the plume of artificially produced SSA to inform the potential MCB’s effectiveness over the Great Barrier Reef. This project is focused on improving our understanding of the horizontal and vertical dispersion of SSA plumes within the marine boundary layer by collecting experimental data during trials of MCB technology.
description: Using drones equipped with aerosol sensors, this study provided the first nearfield data on MCB plumes, showing that droplet evaporation does not prevent the MCB plume rise, challenging previous theoretical assumptions. A subsequent field campaign used a research aircraft, a Diamond HK36TTC ECO-Dimona, to measure plume evolution over larger spatial and vertical ranges. Results confirmed that MCB-generated SSA could reach cloud base heights and impact cloud microphysics over broad areas, validating MCB's potential to mitigate GBR warming.
description: As the study progressed, the need for enhanced airborne sampling arose, leading to the development of a new research aircraft, a Cessna 337, outfitted for detailed aerosol-cloud interaction analysis. Initial field results showed that pollution from Australia’s east coast influenced GBR clouds, increasing droplet concentration and altering cloud microphysical properties, which raises cloud albedo and suppresses rain initiation, as seen in Australian continental clouds. These findings highlight that GBR summer cumulus clouds, prevalent under unstable atmospheric conditions, are suitable for MCB intervention. The study demonstrates that current-generation MCB technology can produce SSA capable of reaching low-level marine clouds, offering a viable tool to prevent coral bleaching. This research provides critical insights into MCB’s feasibility as a climate adaptation measure for the GBR and strengthens the broader scientific understanding necessary for assessing MCB deployment in marine environments.