Dry Deposition Methods Based on Turbulence Kinetic Energy: Part 2. Extension to Particle Deposition Using a Single-Point Model

Though turbulence plays a very important role in driving aerosol particle deposition through various processes and contribution of these processes to deposition velocities varies substantially, turbulence is underrepresented in these processes. Various formulations have been developed to model particle dry deposition; however, all schemes use friction velocity while some formulations use ad hoc factors to represent enhanced impacts of turbulence, but none were formally linked with the three-dimensional (3-D) turbulence. Here, we propose a set of 3-D turbulence-dependent resistance formulations for particle dry deposition simulation and intercompare the performance of new resistance formulations with that obtained from using the existing formulations and measured dry deposition velocity. New parameters such as turbulence velocity scale, turbulence factor, intensity of turbulence, effective sedimentation velocity, and effective Stokes number were introduced into two different particle deposition schemes to improve turbulence representation. For an assumed particle size distribution, the proposed new schemes predicted stronger diurnal variation of particle dry deposition velocity and are comparable to corresponding measurements while existing formulations indicated large underpredictions. We also found that the incorporation of new turbulence parameters either introduced or added stronger diurnal variability to sedimentation velocity and collection efficiencies values, making the new schemes predict higher deposition values during daytime and nighttime when compared to existing schemes. The findings from this research may help improve the capability of dry deposition schemes for better estimation of particle dry deposition and fostering community dry deposition modeling system for use in regional and global models.