Effects of Explicitly Coupling Microphysics Effective Radii to Radiative Transfer Calculations in the Canadian HRDPS Forecast Model

With the increasing complexity in microphysics scheme, more cloud properties are now explicitly calculated, such as the effective radii, and available for the radiative transfer calculations, instead of being parameterized. In Canada, the next version of the operational High Resolution Deterministic Prediction System (HRDPS, Milbrandt et al. 2016, Paquin-Ricard et al.2018) will include an improved coupling for liquid and ice effective radii between the microphysics scheme and the radiative transfer scheme. This study presents a comparison of this new explicit connection against the parameterized version, for two microphysics schemes, namely the Milbrandt and Yau scheme (2005) and the P3 scheme (Morrison and Milbrandt, 2015) in the HRDPS. Results are validated against radiative surface observation networks (ARM, USCRN and SURFRAD), and effects on other weather elements (2m temperature and precipitation) are evaluated.