Observed and Simulated Heterogeneity in Boundary Layer Turbulence and Shallow Convective Clouds during the HI-SCALE Campaign

The Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) campaign was conducted recently in May and September of 2016 near the DOE’s Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site located in Oklahoma. The goal of the HI-SCALE campaign was to provide a detailed set of aircraft and surface measurements needed to obtain a more complete understanding and facilitate improved parameterizations of the lifecycle of shallow clouds. Sampling was done in two periods, one in the spring and the other in the late summer to take advantage of variations in the “greenness” for various types of vegetation, soil moisture availability, and ambient meteorology. The HI-SCALE campaign coincided with the expansion of the SGP site to include additional operational measurements at new sites ~50 km from the center of the site. These new remote sites included Doppler lidars, interferometers, and other instrumentation that can be used to characterize the spatiotemporal variations in boundary layer and cloud properties over the region. We will present a brief overview of the field campaign and then use the measurements to describe the processes contributing to heterogeneity in boundary layer properties and shallow convective clouds. For example, we used the aircraft measurements and found large spatial variations in skin temperature correlated with changes in land use, soil moisture availability, and cloud shading. Multiple passes over the same area reveal how local temperature gradients evolve over time that influence boundary layer characteristics. The observed heterogeneity will also be compared to predictions made by the Weather Research and Forecasting (WRF) model run in a cloud-resolving Large Eddy Simulation (LES) mode with a horizontal grid spacing = 100 m. Both clear-sky and partly cloudy cases will be examined.