Development of an Autonomous Aerosol Chemical Speciation Monitor with Integrated Calibration and Quality Assurance Capability

Clouds play leading role in the Earth's global energy and solar radiation balance. Improving cloud models requires information on the cloud microphysical properties, such as particle size distribution and concentration, cloud composition (droplets, ice particles) and also information on ice crystal shapes (habits). New lightweight and low power instruments for characterization of mixed-phase clouds, suitable for sampling from UAS, tethered balloons, or kite platforms, are needed. This SBIR project continues the development of the Mesa Photonics' in situ optical imaging technology and extends its applicability to mixed-phase cloud characterization. The proposed innovations result in an improved sensitivity and added capability of discriminating between ice particles and water droplets, as well as sizing of droplets in mixed-phase clouds. In addition, the proposed high-resolution hydrometeor imager provides direct complementary information on size and habit of ice particles. The ultimate goal is to develop a technology that is compact, lightweight, low power and inexpensive to make it compatible with small aerial platforms. The Phase I study successfully demonstrated the feasibility of the proposed technical approach, which includes: (1) constructing and characterizing a laboratory prototype of the polarization resolved imaging system capable of discriminating between non-spherical particles and water droplets; (2) demonstrating its performance using a variety of aerosols including salt, ice and dry ice particles as well as mono- and poly-disperse water droplets; (3) building and characterizing a laboratory prototype of a high-resolution imager that provides direct complementary information on the size and shape of non-spherical particles; and (4) identifying the engineering challenges of adapting the technology to small aerial platform and designing flight-ready prototype instrumentation in Phase II. In Phase II, prototypes of the in situ polarization resolved imaging system and the high resolution imager for hydrometeors in mixed phase clouds will be designed, built and characterized. The prototypes will undergo extensive laboratory and field testing, including flight testing on a tethered balloon platform. The successful completion of this Phase I/II program will lead to development of a mixed cloud characterization technology primarily designed for use on small unmanned aerial platforms. When carried over into Phase III and beyond, this project will be of great benefit to the public and the Federal Government. Precise and extensive cloud characterization data will lead to better understanding of the contribution of atmospheric clouds to Earth’s radiative budget and their effect on the global climate. Flexibility and low cost of the proposed technology will make it compatible with a variety of airborne- and ground-based platforms and suitable for other applications such as characterization of atmospheric aerosols and volcanic ash plumes.