Airborne holographic probe for small ice detection

Contrails formed by aircraft emissions are the major component of the radiative impact of aviation, contributing more to forcing than emitted carbon dioxide and nitrogen oxides combined. Efforts to reduce the negative impacts of aviation on climate must therefore account for contrail formation and require better understanding of contrail formation and aging. The research community, including NASA scientists, currently lack an appropriate in situ measurement system capable of characterizing the small ice crystals and droplets relevant to contrail formation and aging processes. We propose development of a new cloud probe designed for operation on research aircraft and other platforms capable of measuring the properties of ice crystals, droplets, and aerosols in the size ranges relevant for contrail formation and potentially distinguishing between them. The proposed instrument would use a digital holographic approach that has been previously demonstrated for cloud measurements, but modified to measure smaller particles than is currently possible with existing instruments. Our system will be capable of delivering the measurements necessary to better understand contrail formation and related aviation impacts on climate. It will also be applicable to a wide range of commercial applications, such as the detection and classification of airborne allergens, pathogens, and other large particles that have impacts on the atmosphere, plant, animal and human health, and visibility, among others.