Aerosol dynamics and gas-particle conversion in dry deposition of inorganic reactive nitrogen in a temperate forest

Genki Katata, Kazuhide Matsuda, Atsuyuki Sorimachi, Mizuo Kajino, Kentaro Takagi
2019 Atmospheric Chemistry and Physics Discussions  
<p><strong>Abstract.</strong> Although dry deposition has an impact on nitrogen status in the forest environments, the mechanism for high dry deposition rates of fine nitrate aerosols (NO<sub>3</sub><sup>-</sup>) observed in forests remains unknown and is a potential source of error in chemical transport models. Here we developed a new multi-layer land surface model coupled with dry deposition and aerosol dynamics processes for a temperate mixed forest in Japan. The processes of thermodynamics,
more » ... of thermodynamics, kinetics, and dry deposition for mixed inorganic aerosols are modeled by a triple-moment modal method. The new model overall reproduces observed turbulent fluxes above the canopy and vertical micrometeorological profiles, as well as inorganic mass and size-resolved total number concentrations within the canopy. Sensitivity tests revealed that the within-canopy evaporation of ammonium nitrate (NH<sub>4</sub>NO<sub>3</sub>) under dry conditions significantly enhances deposition flux for fine NO<sub>3</sub><sup>-</sup> and NH<sub>4</sub><sup>+</sup> aerosols, while reducing deposition flux for nitric acid gas (HNO<sub>3</sub>). A dry deposition scheme coupled with aerosol dynamics may be required to improve the predictive accuracy of chemical transport models for the surface concentration of inorganic reactive nitrogen.</p>
doi:10.5194/acp-2019-703 fatcat:47rvhw6j7zditifl4m2q72hr2a