PNNL

Abstract

Accurately representing flow across the mesoscale to microscale is a persistent road block for completing realistic microscale simulations. The science challenges that must be addressed to coupling at these scales include: 1) What is needed to capture the variability of the mesoscale flow and how do we avoid the impact of modeling across the terra incognita? 2) Which methods effectively couple the scales and capture the correct nonstationary features? 3) What are the best methods to initialize turbulence at the microscale? 4) What is the best way to handle the surface layer parameterizations consistently at the mesoscale and the microscale? 5) How do we assess the impact of improvements in each of these aspects and quantify the uncertainty in the simulations? The U.S DOE’s Mesoscale- to Microscale- Coupling (MMC) Project seeks to develop, verify, and validate physical models and modeling techniques that bridge the most important atmospheric scales determining wind plant performance and reliability, which impacts many meteorological applications. The approach begins with choosing interesting case days for which there are observational data for validation. The team first focused on canonical cases in flat terrain, then moved to nonstationary conditions, and most recently has considered complex terrain cases. This paper describes the scientific aspects of the science challenges and the methods that the team has used to assess multiple approaches to their solution, culminating in recommendations for best approaches for coupled modeling.