Short-term passive tracer plume dispersion in convective boundary layer using a high-resolution WRF-ARW model

Abstract

High-resolution Advanced Research Weather Research and Forecast model is used to understand the role of atmospheric stability on the short-term transport of a continuous release passive scalar plume in three different convective boundary layer regimes: highly convective, combined shear- and buoyancy and shear dominated. Friction velocity to convective velocity ratio and atmospheric stability parameter are used to classify the boundary layer regimes. The effect of release height on the plume transport is addressed by releasing the plumes at surface, near-surface and elevated heights. Total 144 simulations are performed by releasing the plume in the morning and afternoon times of January and August months and at three release heights. Results show that horizontal transport of the plume scales with the initial wind conditions for surface and near-surface releases, and the vertical transport scales with atmospheric stability parameter. Mean plume height and vertical dispersion parameter obtained by convective scaling laws reached their asymptotic values after getting well-mixed in the boundary layer. The dimensionless downwind distance for the mean plume height to reach its asymptote is found to follow a power-law with respect to the atmospheric stability paramter. The coefficient and exponent of the power-law observed are found to be functions of the plume release height normalized by the boundary layer depth.