Aerosols effects on the microphysical properties and the impacts to Numerical Weather Prediction (NWP)

Precise numerical treatment of the effects of aerosols on cloud systems has proven challenging due to the complexity of aerosol-cloud-precipitation interactions. This study describes the implementation, sensitivity tests and results of a new representation of aerosols into the two-moment Milbrandt-Yau (MY2) bulk microphysics scheme using the Global Environmental Multiscale (GEM) NWP model. The scheme has been updated in order to incorporate a climatology of aerosols, that can serve as Cloud Condensation Nuclei (CCN), to initialize the concentration of cloud droplets in the model. High-resolution (2.5-km horizontal grid spacing) simulations, using the 3D GEM atmospheric model over various domains in North America, were performed to test the scheme and examine the sensitivity of aerosols effects on short-term weather forecasts, including sensitivity experiments using different aerosol number concentration