Contrails represent the single largest impact of aviation emissions on the environment, responsible for over half the estimated radiative forcing. Improved understanding of contrail formation processes and the influence of aero-engine emissions is critical to the development of next-generation aero-engines and fuels able to mitigate the warming effects of contrails. Our project will address gaps in the current state-of-the-art measurement capabilities and enable measurements of small ice crystals and aerosols in the initial phases of contrail formation. This will be accomplished through the development of an open-path airborne instrument, capable of measuring the size, refractive index, and asphericity of particles between 100-900 nm in diameter through the use of self-reference interferometry. This instrument would represent the first major advance in airborne wing-mounted aerosol instrumentation in over 40 years. In Phase I, we propose the development and testing of a simplified breadboard optical system to validate our approach. Various particle types with known size, refractive index and/or shape will be tested in the prototype to evaluate its performance. In Phase II, additional testing will be carried out, and a final PMS canister design will be developed and built.
This project would be highly beneficial to NASA ARMD's investigation of aircraft engine particle emissions and their interaction with contrails and contrail cirrus clouds. The instrument would also have wide applications within NASA ESD for aerosol characterization studies, validation of remote sensing observations, and verification of model results. The planned instrument would be suitable for deployment on all NASA airborne science platforms including the DC-8, P-3, B-200, WB-57, and Global Hawk.
The proposed instrument would be highly relevant to other entities performing airborne aerosol measurements, including domestic entities such as DOE, NCAR, NOAA, NSF, and University of Wyoming, and international organizations such as NRC (CA), FAAM (UK), SAFIRE (FR), and DLR (DE). Additional development of this technique for ground-based sampling would have applications beyond atmospheric science.