The most fundamental and complex problems in climate and weather research today are our poor understandings of the basic properties of clouds and our inability to determine quantitatively the many effects cloud processes have on weather and climate. Current climate models indicate that Earth’s average surface temperature will warm from 1.5 to 4.5°C by 2100 due to increases in greenhouse gases, with the large uncertainty attributed to different treatments of clouds in climate models. Winter weather significantly impacts the transportation and power industries, schools and businesses, and severe thunderstorms can cause significant damage and flooding. Improved quantitative precipitation forecasts require a greater understanding of how cloud processes and the related energy release affect the structure and dynamics of storms. Research within the McFarquhar group addresses the overarching theme of clouds and their relation to climate and weather using a combination of field observations, satellite retrievals and numerical modeling studies. Prof. McFarquhar’s work at Oklahoma aims at making fundamental advances in our understanding of cloud properties and processes, and improving our ability to represent clouds in weather and climate models.
Current projects are advancing our understanding of 1) the microphysical structure of snow bands in winter cyclones; 2) the role of cloud microphysical processes in mesoscale convective systems (MCSs) and storms; 3) the properties of tropical clouds (habits, sizes and phases of cloud particles) generated by deep convection; 4) the role of cloud microphysical processes in the rapid intensification of tropical cyclones; 5) processes controlling the amount of supercooled water and freezing drizzle in clouds; 6) how aerosols and other processes affect the evolution of clouds in the Arctic and over the Southern Oceans; 7) the transmission of radiation through the cloudy atmosphere; 8) the representation of clouds in climate and weather models, and especially the development of a stochastic framework for representing cloud processes; 9) the impact of anthropogenic aerosol particles on the water and energy bugets of clouds; 9) the impact of biomass burning aerosols on cloud properties; 10) the retrieval of cloud properties from space-, air- and ground-based remote sensors; 11) the evolution of warm rain; and 12) the use of air- and ship-based instrumentation for measuring the properties of clouds.
Funding is received from the National Science Foundation (NSF), the Department of Energy (DOE), the National Aeronautics and Space Administration (NASA), and the National Oceanic and Atmospheric Administration (NOAA) for this research. In the past few years, my graduate students and I have participated in field projects in Darwin Australia (tropical cirrus), Hobart Australia (Southern Ocean clouds), Cayenne French Guiana (clouds with high ice contents), Swakopmund Namibia (effect of biomass aerosols on cloud properties), Sao Tome Africa (effect of biomass aerosols on cloud properties), Salina Kansas (mesoscale convective systems), Barrow Alaska (arctic mixed-phase clouds), Peoria Illinois (winter storms), and Boulder Colorado (performance of cloud probes). Data collected during these projects are being linked with numerical models having a variety of temporal and spatial scales, including cloud resolving, mesoscale and single column models.
Future field campaigns are planned or are being planned for the Philippines (cloud-aerosol interactions), Sao Tome (biomass aerosols and clouds), Christchurch New Zealand (Southern Ocean Clouds), Kiruna Sweden (arctic clouds), North Carolina (Nor’easters) and the Galapagos Islands (stratus and cumuli clouds). There are many opportunities for graduate students and postdoctoral fellows to participate in these projects.