6.6 Using high-resolution ARM observations to evaluate high-resolution WRF simulations

Fast, Jerome, and Larry Berg, Pacific Northwest National Laboratory

The Atmospheric Radiation Measurement (ARM) Program, has undergone a transformation to include a wide range of new instrumentation. The "megasite" observations are now spread out over a 120 x 120 km area in north Central Oklahoma. The new instrumentation includes several new profiling instruments (e.g. Doppler Lidars) and new surface measurement sites. In addition, the Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) field campaign was conducted near the SGP site during the summer of 2016 to supplement the SGP megasite measurements. The HI-SCALE campaign provided a detailed set of in situ cloud, aerosol precursor, aerosol, and cloud condensation nuclei measurements needed to obtain a more complete understanding and improved parameterizations of the lifecycle of shallow clouds. In this study, we use the extensive SGP site and HI-SCALE measurement dataset to evaluate the High Resolution Rapid Refresh (HRRR) model, that is run over the continental U.S. with a 3 km grid spacing. We determine how well HRRR represents the spatial and temporal variability in meteorological quantities over the SGP megasite, particularly those associated with shallow convective clouds. We find that HRRR underestimates the formation of shallow convective clouds in the region and will provide explanations for that bias. Additional WRF simulations will be used to examine the performance of other convective parameterizations and the effect of spatial resolution (from LES to mesoscale) in contrast with the HRRR results.