Solar Radiation in Different Cloud Regimes Using WRF-Solar Simulations

Clouds have tremendous effects on surface solar irradiance and its direct and diffuse partition, however, accurate simulation of solar radiation in cloudy conditions remains a major challenge. To improve the simulation of clouds, we need to resolve the convections and turbulent flows that control the evolution of clouds. In this study, we focus on the influence of cloud types and domain sizes on the surface solar irradiance. First, a number of cloudy conditions will be tested, specifically for the shallow cumulus v.s. stratocumulus, and drizzling clouds v.s. non-drizzling clouds. The simulation of each cloudy condition will be conducted using the state of art Weather Research and Forecast model designed for solar radiation simulation and forecasting (WRF-Solar). The partition of solar energy will be examined in each cloud regime and evaluated against the measurements of the cases at the DOE ARM SGP Site. Second, we will explore the effect of model settings on the simulated clouds and solar radiation. In particular, we aim to answer the following questions: 1) How different the results will be using different model configurations? 2) What is the lower limit of the domain size that will produce reasonable simulation? The results will provide physical insight into forecasting of solar radiation in cloudy conditions.