Simulating gas-aerosol-cirrus interactions: Process-oriented microphysical model and applications

[摘要] This work describes a process-oriented,microphysical-chemical model to simulate the formation and evolution of aerosols and ice crystals under the conditions prevailing in the upper troposphere and lower stratosphere. The modelcan be run as a box model or along atmospheric trajectories, and considers mixing, gas phase chemistry of aerosolprecursors, binary homogeneous aerosol nucleation, homogeneous and heterogeneous ice nucleation, coagulation,condensation and dissolution, gas retention during particle freezing, gas trapping in growing ice crystals, andreverse processes. Chemical equations are solved iteratively using a second order implicit integration method. Gas-particle interactions andcoagulation are treated over various size structures, with fully mass conserving and non-iterative numerical solutionschemes. Particle types include quinternary aqueous solutions composed ofH₂SO₄, HNO₃, HCl, and HBr with and without insoluble components, insoluble aerosol particles, and spherical or columnarice crystals deriving from each aerosol type separately. Three case studies are discussed in detail to demonstrate thepotential of the model to simulate real atmospheric processes and to highlight current research topics concerningaerosol and cirrus formation near the tropopause. Emphasis is placed on how the formation of cirrus cloudsand the scavenging of nitric acid in cirrus depends on small-scale temperature fluctuations and the presence ofefficient ice nuclei in the tropopause region, corroborating and partly extending the findings of previous studies.

[学科分类] 大气科学