Aerosol Size Distribution Measurements for Marine Platforms

Oceans cover roughly 70% of the Earth, but measurements over the seas of key aerosol properties like the number size distribution, light scattering, and light absorption are almost non-existent. Longterm records of these types of data are critically needed to validate climate model parameterizations of aerosol sources and sinks, seasonal variability, and aerosol-cloud interactions in the marine boundary layer. Deployment of new, marine-hardened measurements on-board commercial ships-of-opportunity would provide important information on the background state of the marine aerosol and how the size distribution varies around shipping lanes and under conditions of mixing between background marine and anthropogenically perturbed airmasses. With simultaneous meteorological measurements (i.e., wind speed and direction), information on aerosol sources like sea salt production from sea spray and the diurnal sea salt cycle, could be obtained. Long term measurements will provide statistically significant datasets from the repeated, similar ship track passages that will better constrain model inputs. Specifically, this SBIR project will support the development of a self-contained, self-powered system to autonomously measure the aerosol size distribution, aerosol light absorption, and local meteorological data on-board commercial shipping vessels and other marine platforms. Phase I of the project will develop designs and prototypes of the key sub-systems to test marinehardened components and minimize power consumption. Prototypes will be tested with known particle sizes and chemical properties and under a range of marine conditions to assess performance. Commercial applications and other benefits include creating a new, stand-alone tool to study aerosol climate forcing, improving weather forecast models, creating new data sets to validate climate and other models in ocean settings, and creating a real-time monitor of ship exhaust to improve fuel-use efficiency.