A Miniaturized, Lower Cost Static Diffusion Chamber for Cloud Condensation Nuclei Measurements

The impacts of aerosol on cloud properties remains a major obstacle to better understanding of Earth’s changing energy budget and quantifying their impacts is a DOE objective and of broader benefit to the public. Cloud condensation nuclei (CCN) have a potentially major impact on cloud droplet number and size, and thereby affect cloud radiative properties, cloud lifetime, and precipitation. Improving observational capabilities for CCN is required to advance understanding and extend current measurements into a wider geographic region, including under-sampled regions, and for longer time periods. There is also a need for smaller, lower-cost and lightweight instruments capable of measuring CCN for use on rapidly advancing unmanned platforms, including unmanned aerial vehicles as well as tethered and free balloons. To address these needs, we propose commercial development of a simple, lower cost, low power consumption and small footprint CCN counter based on the static diffusion chamber design. Static diffusion chambers produce a controlled supersaturated region by controlling the temperature gradient between two wet plates. Particles exposed to the supersaturated environment can activate as droplets, and can be counted to determine the number of CCN active at a given supersaturation. The proposed instrument is an extension of the first commercially available CCN counter, which has been significantly overhauled to take advantage of developments of extremely low-cost digital cameras, lasers, mechanical hardware, electronics, computers, and image processing software. We anticipate a factor of 100 reduction in cost compared to existing commercial CCN counters and large reductions in size and weight (the miniaturized device is approximately 6 x 3 x 3 inches; 600 g). In addition to mechanical and electrotonic design and development work, a major component of our proposed development effort focuses on calibrating and characterizing the CCN counter against known laboratory standards and evaluating its performance against a widely adopted commercial CCN counter. We will also evaluate the device’s suitability for its intended application on UAS and remote measurement locations, including environmental conditioning tests and longevity and stability tests. Future commercial applications include use by atmospheric researchers seeking a low cost, high performance and easy to use instrument for use on UAS and field studies.