Chemical retention and diffusional uptake of secondary organic aerosol precursors in hydrometeors

Abstract

The phase changes of hydrometeors can cause chemical exchange that may lead to transport of certain water-soluble organic compounds (WSOC) between the lower troposphere and the upper troposphere lower stratosphere (UTLS). Specifically, during droplet freezing WSOC dissolved in the supercooled cloud droplets can be released into the gas phase. Alternately, many volatile organic compounds can be removed from the UTLS via ice phase deposition scavenging. These microphysical and multiphase chemical processes may lead to the vertical redistribution of substances that become available for atmospheric processes in the upper troposphere. Motivations for understanding the processes of chemical retention and diffusional ice uptake as well as descriptions of them are detailed in this dissertation as justification for their investigation through several publications. These publications detail the measurement of retention coefficients and ice-gas partitioning coefficients through the use of wind tunnel studies, acoustic levitator experiments, and flowtube experiments. These measurements complicate the current understanding of the relationship between chemical retention and Henry’s law solubilities as well as reveal previously unknown entropy-enthalpy compensation behavior resulting from diffusional ice uptake.