Atmospheric Aging Impacts on the Ice Nucleation Abilities of Mineral Dust in the Cirrus Cloud Regime
CAROLINA RAMIREZ-ROMERO, Luis A. Ladino, Sebastián Mendoza-Téllez, Jonathan Abbatt, University of Toronto
Abstract Number: 219
Working Group: Aerosols, Clouds and Climate
Abstract
After sea spray, mineral dust is the second-largest natural contributor of airborne particles worldwide. Due to its abundance and physicochemical properties, mineral dust influences the formation of mixed-phase and cirrus clouds by acting as ice nucleating particles (INPs). In particular, feldspars can nucleate ice under cirrus cloud conditions at a relative humidity with respect to ice (RHice) of ~127%. For this reason, feldspars may be good candidates for cirrus seeding by promoting cloud thinning, a solar management technique to mitigate climate warming. However, it is unknown how aging mechanisms in the upper troposphere may modify the physicochemical properties of feldspars, affecting their ice nucleation (IN) and cloud seeding abilities.
Here we present results on the ice nucleation abilities via deposition nucleation, before and after aging mechanisms, of various types of feldspar (i.e., orthoclase, plagioclase, and microcline). Experiments were conducted in the University of Toronto Continuous Flow Diffusion Chamber (UT-CFDC) at temperatures between 213 and 223 K. Particle aging was induced by the formation of organic coatings, specifically tricarballylic acid and dioctyl sebacate, which were subsequently oxidized by OH radicals in the Toronto Photo-oxidation Flow Tube. Different aging conditions (e.g., equivalent to days to weeks in the atmosphere) were studied to evaluate the effect on IN efficiency. Our results indicate that the IN ability of feldspars is influenced by aging mechanisms, conditions expected in the upper troposphere.