Research Seminar Abstract
Condensed phase matter in the atmosphere perturbs the earth’s radiative balance, impacts climate, adversely affects human and biological health, degrades visibility, affects cloud formation, and alters atmospheric chemistry. The residence time of condensed phase matter in the atmosphere is a function of its sources and sinks. Black carbon (BC) is one form of condensed phase matter in the atmosphere that impacts atmospheric temperature, cloud formation and properties, the albedo of snow and ice surfaces, and the timing of snowmelt. Parameterization of BC dry deposition is particularly limited due to the lack of available instrumentation for measuring the process, and thus there is a lack of observational datasets with which to evaluate existing models. We present observations of dry and wet deposition rates of size-resolved refractory black carbon (rBC), coated rBC, and total aerosol number by eddy covariance technique using a single particle soot photometer (SP2; Droplet Measurement Technologies Inc.) and ultra high sensitivity aerosol spectrometer (UHSAS; Droplet Measurement Technologies Inc.). Using these data, we show that wet deposition dominates the removal of rBC from the atmosphere and that a size-dependent loss rate exists for these particles and that the size-dependent loss of rBC is influenced by the chemistry occurring at the surface of the particle. These observational data allow for a more complete evaluation of existing climate models and the development of a tractable parametrization for use in global climate models.