Topic 27a: Monodisperse aerosol generator for field calibration of atmospheric measurement instrumentation

Aerosols and clouds play an important role in the Earth's global energy and solar radiation balance and hydrological cycle. However, the processes that govern cloud-aerosol interactions, drizzle formation and precipitation are poorly understood and represent major sources of uncertainty in predictive models. The DOE ARM Facilities and other global atmospheric measurement networks provide data that are used for development and improvement of these models. Quantifying the uncertainty of these measurements is critically important. Although the majority of instruments may be well-characterized in a laboratory setting, deploying them in field conditions greatly increases the measurement uncertainties. Field calibration capabilities need to be developed. This SBIR project is developing an innovative portable, battery-powered aerosol generator for field calibration of atmospheric measurement instrumentation such as in situ cloud droplet probes and aerosol sizing and precipitation measurement instruments. The ultimate goal is to develop a technology that is compact, robust, low-maintenance, user-friendly and inexpensive to allow wide-scale deployment of the proposed aerosol generators over atmospheric measurement facilities. The Phase I study successfully demonstrated the feasibility of the proposed technical approach. The main results include: (1) constructing and characterizing a laboratory prototype of the monodisperse aerosol generator; (2) demonstrating its performance characteristics under a wide range of conditions and outlining the calibration procedures; and (3) identifying the engineering challenges of transitioning the technology to a standalone portable prototype useful for field calibration of atmospheric measurement instrumentation in Phase II. In Phase II, a field deployable prototype of the monodisperse aerosol generator will be designed, built and characterized. The prototype will undergo extensive laboratory and field testing. As a result, a field calibration technology for atmospheric measurement instrumentation that is basically ready for commercialization will be developed. Successful completion of this program will lead to development of a monodisperse aerosol generator primarily designed for field calibration of a variety of atmospheric measurement instruments. When carried over into Phase III and beyond, this project will be of great benefit to the public and the Federal Government. Improved measurement accuracy will lead to development of more precise atmospheric models and, hence, better understanding of the contribution of atmospheric aerosols and clouds to Earth’s radiative budget and global climate trends.