Adaptive Sampling for In Situ Cloud Probe

Clouds play a leading role in the Earth's global energy and solar radiation balance and hydrological cycle. Improving cloud models requires detailed information on the cloud microphysical properties, such as droplet size distribution and number density, liquid water content and cloud composition (droplets, ice particles), which can only be provided by aerial in situ measurements. However, for many atmospheric measurement instruments, the lack of flexibility in selecting the operational mode during operation can lead to uncertainties in sampling and measurement characteristics under continuously varying atmospheric conditions. The goal of this SBIR project is a deep modification of the existing Mesa Photonics' Cloud Droplet Measurement System (CDMS) in order to implement real-time automatic adaptive sampling based on the acquired in situ data and environmental conditions. An innovative optical layout based on state-of-the-art optical technologies will be implemented to add the following capabilities to CDMS: (1) discriminating between water and ice hydrometeors; (2) automatic switching between regular and sparse/large hydrometeor imaging modes; and (3) other automatic adaptive sampling capabilities including variable sample volume and dynamic range. The Phase I research will focus on: (1) designing and building a laboratory prototype of the proposed instrument implementing the extended capabilities; (2) characterizing the laboratory prototype and demonstrating its performance characteristics and adaptive sampling under laboratory conditions and in a cloud chamber; and (3) evaluating the feasibility of the proposed technology and identifying the engineering challenges of designing a field deployable prototype instrument in Phase II. Successful completion of this Phase I/II program will lead to development of a versatile instrument for in situ cloud measurements that is capable of acquiring high-quality data under continuously changing atmospheric conditions, compatible with a variety of small aerial platforms and basically ready for field deployment and commercialization. When carried over into Phase III and beyond, this project will be of great benefit to the public and Federal Government. Availability of precise and extensive cloud microphysical data will lead to better understanding of the contribution of atmospheric clouds to Earth’s radiative budget and global climate trends. Other potential applications include characterization of atmospheric aerosols, volcanic ash plumes and industrial/agricultural sprays.