How well do numerical model simulations reproduce the diurnal cycle of radiation, valley wind, and cloud cover in the Colorado East River Basin?

Understanding the cloud formation in mountainous regions is important for understanding the surface water and energy budgets of these regions. Cloud formation is greatly influenced by orographic uplift and requires favorable synoptic conditions. Once formed, clouds greatly affect surface solar irradiance, thereby impacting the surface energy budget. We analyzed the diurnal cycles of cloud cover and radiation in relation to valley winds in the Colorado East River Basin using observational data collected in 2022 and 2023 by ARM Surface Atmosphere Integrated Field Laboratory (SAIL), the Study of Precipitation, Lower Atmosphere, and Surface for Hydrometeorology (SPLASH), and the Sublimation of Snow (SOS) campaigns. Our analysis of observations revealed a distinct diurnal cycle of wind direction at four locations within the East River Basin, accompanied by frequent cloud formation during the summer. The main aim of this study is to determine how well these observational characteristics can be captured in mesoscale numerical model simulations. We primarily analyzed the CONUS404 dataset, which is Weather Research and Forecasting (WRF) simulations at a 4-km resolution, containing comprehensive meteorological data for the CONUS region over the past 40+ years. We also analyzed 1-km resolution WRF simulations.