RRM Application

Abstract

The regionally-refined model (RRM) team has established the CONUS RRM (CONUS: 0.25 degree, Outside: 1 degree) free-running and nudging prototypes for other ACME teams. The RRM configuration is developed as an economical modeling framework to study the behavior of a global uniform high-resolution model in the refined region. In this work, we apply the nudged (outside the refined domain) RRM to study the impacts/sensitivities of topography, horizontal resolution, convection schemes, and convection parameters to the precipitation and convection over North America. Subtle differences in precipitation are found along the front-range of the Rocky and the large-scale precipitation features are less intense with fine/steeper topography. However, features such as resolving Sierras are more marked. The propagation of convection compares better with the observations when the Zhang-McFarlane deep convection scheme is off. Contrast of RRM and uniform high-resolution simulations with candidate convection schemes (e.g., CLUBBe) are further used to demonstrate the values of utilizing cost-effective RRM to assess the performance of new parameterizations at target high resolution.