In-situ measurement of large aerosols
Aerosols are common atmospheric constituents, and important for a vast array of applications, such as climate science, public health, and agriculture. A subclass of aerosols, called coarse-mode aerosols (CMAs), are much less numerous than the smaller fine-mode aerosols, but can nevertheless dominate the mass distribution of all aerosols, and thus have very notable impact on e.g. the radiative effects of the total aerosol population. CMA interactions with light are governed not only by the size but also the composition and the shape of the particle, and these hard-to-measure details can dictate what kind of effects a given particle population has. Experimental light scattering aided by computational methods can be used to size and characterize the particles in a freely flowing medium in a rapid and contact-free manner, opening new avenues for in-situ atmospheric research. One example application is digital holography, which can produce pseudo-3D images of particles, and enables automatic, real-time sizing and classification of many types of atmospheric aerosols.
Bio: Osku Kemppinen is a postdoctoral fellow at Kansas State University. He joined KSU in August 2016 after receiving his Ph.D. in computational physics jointly from Aalto University, Finland and Finnish Meteorological Institute. His prior work has focused on supercomputing simulations on how morphology dictates light scattering by aerosols, in addition to separate research, development and engineering on Martian meteorological instruments and their data, most notably REMS on-board the Mars Science Laboratory. At KSU he is working on miniaturizing an existing proof-of-concept design of digital holography to a field-portable size required for most practical applications, and developing the associated computing algorithms for successful particle classification.