This project concerns new techniques for aerosol-cloud characterization from high-speed aircraft, including 1) size-segregated sampling of activated particles with a new dual-channel counterflow virtual impactor for analysis of multi-phase clouds; 2) a blunt-body sampler design for sampling non-activated particles without contamination from droplet shatter; and 3) a fast aerosol mobility spectrometer for particle size and compositional characterization. Fundamental aerosol and fluid dynamics modeling will be coupled with numerical simulations and wind-tunnel experiments to obtain optimized instrument designs. A sampler for aerosol-cloud characterization from a wide range of aircraft platforms and a fast sizing particle instrument that could be extended for tandem differential mobility analyzer (TDMA) measurements of size-resolved compositional characteristics of atmospheric aerosol will be built.
The educational plan includes a K-12 outreach program, undergraduate research, and new course development. An outreach program will be developed to bring cloud physics and atmospheric science fundamentals to high school students. Undergraduate students will be exposed to atmospheric science topics through participation in summer and honors research projects. Research results will be integrated with a new graduate course in experimental aerosol techniques, with emphasis on learning through a project-based approach. A web-based tool will be developed with participation by undergraduate students, to provide visualization of aircraft-particle interactions for the atmospheric sampling community. Recruitment of underrepresented students will be coordinated both through Clarkson's minority programs and with additional efforts at Southern University, Baton Rouge, LA.
Accurate modeling of long-term changes in global climate requires detailed consideration of the role of aerosol particles in modulating Earth’s radiative budget. Of particular importance and challenge is the consideration of the aerosol indirect effect, i.e., the role of aerosol in cloud formation and the subsequent interaction of cloud droplets with solar radiation. The focus of this CAREER grant was to develop new aerosol sampling and measurement techniques to enable detailed study of aerosol-cloud systems from aircraft. The specific objectives of this project were to: 1) develop a new inlet for sampling interstitial aerosol from high-speed aircraft without contamination from artifact particles from shatter of cloud droplets and 2) develop a new instrument for near real-time measurement of size distributions of these particles. A new interstitial aerosol inlet, called the Blunt-body aerosol sampler (BASE), was designed using numerical modeling and tested in a wind-tunnel, prior to aircraft deployment. Aerosol samples obtained from BASE flown on National Center for Atmospheric Research’s C-130 aircraft were seen to be largely free of shatter artifacts in a range of cloud systems. The availability of this new inlet plugs a critical gap in our ability to study cloud systems from aircraft and in combination with downstream analytical instruments, unprecedented information about the non-activated aerosol fraction within clouds is possible with the inlet. The complete characterization of an aerosol-cloud system from aircraft platforms requires simultaneous measurements of the properties of the activated (cloud) and non-activated (interstitial aerosol) particles. While most aerosol and cloud properties can be measured in near real-time, measurement of particle size distributions often require several minutes, rendering this data unusable for aircraft-based cloud studies. To overcome this limitation, we designed a fast aerosol sizer that combines a newly developed high-flow dual-channel differential mobility analyzer (HD-DMA) with multiple CPCs to enable particle size distribution measurements in near real-time even under the low concentration conditions typical in the atmosphere. The instrument measurement characteristics were modeled theoretically and new algorithms were developed for accurate calculation of size distribution from the instrument data. The deployment of the new instrument downstream of BASE during the ICE-T campaign has helped obtained some of the first near real-time measurements of interstitial particle size distributions in a variety of cloud systems. Analysis of this data set is currently underway and its expected to provide critical data towards the development and testing of advanced aerosol-cloud models. This CAREER grant supported the theses of three PhD students and provided research experience for five undergraduate students. In addition, several K-12 course modules were developed and disseminated to local schools on topics related to air quality, climate, and environment. The grant also supported the participation of the PI in the development of an undergraduate class for engineering students on climate change. The grant has, thusfar, resulted in eight publications in peer-reviewed journals.
