Using convection-permitting Weather Research and Forecasting (WRF) simulations, this study examines how marine cloud brightening over the Great Barrier Reef (GBR) depends on aerosol emission strength and spatial distribution. Densely spaced sources generate more uniform aerosol enhancements and stronger cloud microphysical responses than sparsely distributed sources, despite identical emissions. Cloud droplet number concentration (CDNC) and optical depth increase strongly, indicating a dominant Twomey effect, while cloud water and coverage respond weakly.