HISCALE

Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE)

24 April 2016 - 23 September 2016

Lead Scientist: Jerome Fast

Observatory: SGP

Cumulus convection is an important component in the atmospheric radiation budget and hydrologic cycle over the southern Great Plains and many other regions of the world, particularly during the summertime growing season when intense turbulence induced by surface radiation couples the land surface to clouds. Current convective cloud parameterizations contain uncertainties resulting partly from insufficient coincident data that couple cloud macrophysical and microphysical properties to inhomogeneities in boundary layer and aerosol properties. The Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) field campaign was designed to provide a detailed set of measurements needed for a more complete understanding of the life cycle of shallow clouds by coupling cloud macrophysical and microphysical properties to land surface properties, ecosystems, and aerosols. HI-SCALE consisted of two four-week intensive observational periods, one in the spring and the other in the late summer to take advantage of different stages and distribution of greenness for various vegetation near the ARM Climate Research Facility's Southern Great Plains Megasite (SGP), as well as aerosol properties that vary during the growing season. Most of the instruments were deployed on the ARM Aerial Facility (AAF) Gulfstream-159 (G-1) aircraft, including those that measure atmospheric turbulence, cloud water content and drop size distributions, aerosol precursor gases, aerosol chemical composition and size distributions, and cloud condensation nuclei concentrations. Aerosol microphysical property measurements supplemented routine ARM aerosol measurements made at the surface. The G-1 completed transects over the SGP Central Facility at multiple altitudes within the boundary layer, and within and above clouds. The extensive measurements collected during the campaign will be coupled with routine ARM SGP measurements as well as large-eddy simulation (LES), cloud-resolving, and cloud-system-resolving models. Through integrated analyses and modeling studies, scientists will be able to quantify the influence of inhomogeneities in land use, vegetation, soil moisture, convective eddies, and aerosol properties on the evolution of shallow clouds. This includes the feedbacks of clouds on the downwelling radiation reaching the surface and associated changes in the surface heat, moisture, and momentum fluxes, and on aerosol photochemical processes. Findings from the data analyses and modeling studies will be used to develop improved parameterizations for the next generation of climate models that are expected to have grid spacing of approximately 10 kilometers. In addition, the aircraft and surface measurements provided critical in situ measurements of the boundary layer, cloud microphysics and dynamics, and aerosol properties that can be used to evaluate the new routine LES modeling activity at the SGP site and various current and new ARM retrievals. Campaign periods: 2016.04.24--2016.05.21 2016.08.28--2016.09.23