OU Researchers Study Cloud Data from Tasmania to Texas

By

Date

NORMAN, OKLA. – Two atmospheric researchers at the University of Oklahoma have received funding from the Department of Energy’s Atmospheric System Research program. Greg McFarquhar, Ph.D., and Zachary Lebo, Ph.D., will both lead projects to advance understanding of cloud processes by utilizing datasets from distinct atmospheric field campaigns.

McFarquhar, director of the Cooperative Institute for Severe and High-Impact Weather Research and Operations (CIWRO) and a professor in the School of Meteorology at OU, will analyze cloud data from Tasmania. Using data collected during the ongoing Cloud and Precipitation Experiment at Kennaook, or CAPE-K, McFarquhar will examine the relationship between cloud properties and environmental conditions over Tasmania.

One key focus will be on ice multiplication processes, such as how ice is generated in clouds. McFarquhar will use the CAPE-K data and modeling simulations to examine how ice is multiplied in these clouds, with the broader aim of further informing global climate and earth systems models.

McFarquhar says that the advantage of the CAPE-K data is that the duration of collection, from April 2024 to September 2025, gives scientists a good picture of what controls these cloud properties. He will partner with Yongjie Huang, Ph.D., a research scientist with OU’s Center for Analysis and Prediction of Storms, to run simulations examining how these cloud properties depend on environmental conditions and aerosols.

“If we can get these simulations well-verified against the observations that we collect within the models, we can turn processes on and off to give us a lot of important information on what the processes are most responsible for the generation of ice,” said McFarquhar.

Lebo will work with data collected during the Tracking Aerosol Convection Interactions Experiment, or TRACER. TRACER and its sister campaign ESCAPE (Experiment of Sea Breeze Convection, Aerosols, Precipitation, and Environment) took place in Houston, Texas, an area selected for its frequent thunderstorms, as well as the added interest of the influence of the metropolitan area on storm processes. During these campaigns, data on cloud and aerosol interactions in deep convection were collected by a variety of observation instruments. Lebo will leverage the TRACER data to link the processes that are ongoing inside of thunderstorms to the actual development of the storms themselves.

“There’s a huge scale gap here that we’re trying to bridge to understand how these small-scale processes are affecting the large scale of these storms and vice versa,” said Lebo.

Lebo will examine the ongoing processes on the scale of hydrometeors. Hydrometeors, such as raindrops or ice crystals, are microscopic –10s to 1000s of micrometers in size – compared to the large-scale properties such as temperature and wind that vary at the scale of several kilometers. Bridging that vast gap will strengthen and expand scientists’ understanding of the processes and properties of convective clouds.

Lebo says a better grasp of how these storms form and evolve will pave the way for more accurate simulation and forecasting of these storms. Processes that are determined to be critical in the evolution of thunderstorms could also be used as guidance for future model development.