How does the novel EDMF-AERO model help to study Aerosol-PBL Interactions? Initial testing and results

Understanding the interactions between atmospheric aerosols and the evolution of the planetary boundary layer (PBL) is of paramount importance for human health, climate, and forecasting models. In this study, an eddy-diffusivity mass-flux (EDMF) model is coupled with a radiative transfer model (RTM) to investigate the effects of aerosol optical properties on the growth and thermodynamics of the PBL, or the so-called aerosol-PBL interactions (API). The developed model, called EDMF-AERO, is first extensively validated against in-situ radiosonde and microwave radiometer (MWR) observations, showing very good performance. Having established the model’s satisfactory accuracy, we investigated the impact of aerosol properties and model parameters on PBL evolution. In particular, we studied and confirmed the previously identified positive feedback loop between PBL growth and aerosol absorptivity known in the literature as the stove and dome effects (Ma et al. 2020). For the stove case higher 𝜏₅₀₀ and lower 𝜔 cause PBL to grow and heat up faster. In extreme cases (𝜏₅₀₀ = 1.5, 𝜔 = 0.8), the PBL growth speeds up ~40% and warms up ~40% faster compared to the reference. For the dome case higher 𝜏₅₀₀ and lower 𝜔 cause PBL to grow and heat up slower. In extreme cases (𝜏₅₀₀ = 1.5, 𝜔 = 0.8), the PBL growth slows down ~30% and warms up ~30% slower compared to the reference. In both cases, the feedback loop severely impacts surface PM concentrations and enhances heat index. Based on the sensitivity runs, a parameterization relating the τ₅₀₀ and 𝜔 on the PBL heating rate and PBL growth is suggested, which could be easily employed in atmospheric and chemical transport models. The EDMF-AERO model developed in this study proves to be a valuable tool for studying API.