Ship plume dispersion rates in convective boundary layers for chemistry models

[摘要] Detailed ship plume simulations in various convective boundary layersituations have been performed using a Lagrangian Dispersion Model driven bya Large Eddy Simulation Model. The simulations focus on the early stage (1–2 h)of plume dispersion regime and take into account the effects of plumerise on dispersion. Results are presented in an attempt to provide toatmospheric chemistry modellers a realistic description of characteristicdispersion impact on exhaust ship plume chemistry. Plume dispersionsimulations are used to derive analytical dilution rate functions. Eventhough results exhibit striking effects of plume rise parameter ondispersion patterns, it is shown that initial buoyancy fluxes at ship stackhave a minor effect on plume dilution rate. After initial high dispersionregimes a simple characteristic dilution time scale can be used toparameterize the subgrid plume dilution effect in large-scale chemistrymodels. The results show that this parameter is directly related to thetypical turn-over time scale of the convective boundary layer.

[学科分类] 大气科学