Performance evaluation of modified Gaussian and Lagrangian models under low wind speed: A case study

Highlights: • Dispersion under low wind speeds are crucial for impact assessment. • At low wind speeds meandering leads to wider plumes. • Dispersion is simulated using modified Lagrangian and Gaussian models. • The simulated crosswind plume standard deviations with Hanford-67 tracer data. - Abstract: In this study, we analyze the performance of the Gaussian model with improved dispersion parameters and a Lagrangian dispersion model with coupled Langevin equation under low wind speed conditions. We used data collected from Hanford-67 tracer experiment for comparison of the crosswind plume standard deviation simulated by these models. The study makes use of two cases where wind speed is less than 2 m/s. The results show that the simulated crosswind plume standard deviation using Gaussian model with improved dispersion parameters and Lagrangian dispersion model with coupled Langevin equation is in good agreement with observation compared to Gaussian model with Pasquill-Gifford dispersion parameters and Lagrangian models based on standard Langevin equation.