Examining the Influences of Changing Aerosol and Thermodynamics on Southeastern Isolated Convective Clouds using New Observations and Advanced Modeling

Sean W. Freeman, University of Alabama in Huntsville, Principal Investigator

In the Southeastern United States, isolated cumulus convective clouds, the puffy clouds that  are ubiquitous throughout the year. These convective clouds are significant locally due to the severe weather they can produce, including flooding rainfall; regionally due to their importance in the regional water cycle; and globally through their feedback on the global climate system. Because of their importance and ubiquity, it is critically important to understand how these isolated convective clouds respond to the changing climate in the Southeast’s unique environment. Two critical aspects of the environment in the Southeast that impact these clouds are the atmospheric conditions, such as winds, humidity, and temperature (collectively called thermodynamics)

thermodynamics

The study of the effects of work, heat, and energy on a system. Thermodynamics is only concerned with large scale observations.

Source: NASA Source

, and the amount and type of aerosol

aerosols

Small particles or droplets, such as wildfire smoke, volcanic gases, or salty sea spray, that float in the air. They are emitted by both natural events and human activities.

Source: NASA Global Climate Change Source

particles, small particles in the atmosphere that cloud drops form on.

 The proposed research is a pilot study, with the initial goal of understanding how the growth and lifetime of isolated raining convective clouds in the Southeast are impacted by local changes to the aerosol and thermodynamic environments. This research will be performed using the novel early observations provided by the deployment of the US Department of Energy Atmospheric Radiation Measurement (ARM) Mobile Facility-3 to North Alabama, a state-of-the-science cloud tracking algorithm (the Tracking and Object-Based Analysis of Clouds package, tobac), and high-resolution numerical model simulations. In both observations, where a Near-Real-Time database of clouds will be identified and tracked, and in the simulations, where tobac will track clouds using simulated radar reflectivity, we will examine how cloud lifetime and growth are impacted by changes in aerosol conditions when holding thermodynamics constant.