The fundamental science question behind marine cloud brightening (MCB) as a climate intervention mechanism is whether the reflectivity of marine boundary layer clouds can be deliberately increased in a controlled manner by releasing aerosols (small particles; in this case, small sea salt particles) into the marine boundary layer in targeted regions. Aerosol emissions influence cloud reflectivity through changes in the cloud droplet number concentration, which generally increases with the addition of aerosols. However, whether and how much a cloud field is brightened with the addition of aerosols depends on multiple factors, including the meteorological conditions and the concentration and size of both the injected aerosol and aerosol already present in the atmosphere. In addition, the net effect on reflectivity will depend on how the clouds respond to having higher droplet number concentrations and smaller droplet sizes. These responses may augment or offset the initial reflectivity changes in the perturbed clouds, and they may also affect the reflectivity and lifetime of clouds in adjacent areas. This project aims to conduct a series of high-resolution model runs that simulate cloud fields typical of those that would be targeted for MCB, with two goals: First, the simulations will be tested against observations to quantify how well the model reproduces unperturbed cloud fields under a range of meteorological and background aerosol conditions. Second, the model will be run to test cloud responses to the addition of small sea salt aerosol representative of what would be used for intentional marine cloud brightening, under a range of realistic meteorological and background conditions.