CONTRAIL FORMATION AND IMPACTS ON AEROSOL PROPERTIES IN AIRCRAFT PLUMES - EFFECTS OF FUEL SULFUR-CONTENT

The formation and evolution of fine particles and ice contrails in an aircraft exhaust plume containing varying amounts of fuel sulfur have been simulated using an advanced aerosol microphysics model. The ''cor e'' sulfate and soot particles are tracked during the contrail formati on and dissipation phases. When ion electrostatic effects are incorpor ated into the microphysics, sulfuric acid vapor emitted by high-sulfur -content fuels generates water-soluble particles that are large enough to be activated into contrails, improving the agreement between simul ations and measurements. Our results also suggest that ice crystals fo rmed in contrails efficiently scavenge vapors and particles, creating a sulfate aerosol accumulation mode that may contribute to cloud CCN/I N. The size distributions of aerosols produced both in the presence an d absence of contrails agree reasonable well with the two characterist ic types observed in the plumes of commercial aircraft.