<span>The aim of Marine Cloud Brightening (MCB) is to purposely inject artificially generated sea spray aerosols (SSA_a) into low-level marine clouds, increasing their albedo with the objective of cooling the ocean surface beneath the clouds. Over the Great Barrier Reef (GBR), Australia, MCB is under research as a potential intervention to alleviate coral bleaching. Attributing cloud microphysical perturbations to MCB requires the ability to detect and trace SSA_a and distinguish that from other local sources, including the exhaust from research aircraft, research vessel, and generators used to power the MCB technology. Here, we present a novel &ldquo;tracer&rdquo; method using</span> in situ airborne measurements of the non-volatile aerosol ratio to identify the aerosol plume emanating from the spraying vessel and apportion aerosols between <span>SSA_a and combustion exhaust. A total of 14 flights were analysed using downwind, upwind, crosswind, or a combination of these </span>sampling <span>legs. </span>Aircraft-sampled plumes of <span>SSA_a</span> and exhaust exhibited contrasting non-volatile properties. <span>Aerosol plume detections were identified using aerosol number concentration, and a mixing ratio model was constructed to apportion the detected plumes between SSA_a </span>and exhaust particulates. The <span>&ldquo;tracer&rdquo; method reliably allowed tracking of the vessel-generated SSA_a</span> across all sampling events<span> as </span>the plume<span> spread downwind from the spraying </span>vessel<span>. </span>The majority of sampled plumes were found to be mixed SSA_a and exhaust. <span>This technique enables the tracking and identification of MCB aerosol in the natural marine atmosphere without the addition of a chemical tracer. Reliable plume identification is a prerequisite for studying the transport and dispersion of MCB aerosols and determining how they influence aerosols and clouds in the marine boundary layer.</span>