The Role of Aerosol Properties in Determining Deep Convection Cloud Properties

SARAH D. BROOKS, Seth Thompson, Bo Chen, Taylor Peña, Brianna Matthews, Anita Rapp, Christopher Nowotarski, Ziying Lei, Milind Sharma, Texas A&M University

     Abstract Number: 453
     Working Group: Aerosols, Clouds and Climate

Abstract
Accurately characterizing the vertical distribution of aerosols and their cloud-forming properties is crucial for understanding aerosol-cloud interactions and their potential impact on deep convection. During the DOE TRACER campaign, we combined mobile laboratory van, micropulse lidar and radiosonde measurements to observe the surface concentration, vertical distribution and cloud-forming properties of aerosols. Aerosols may influence deep convective clouds by serving either warm could condensation nuclei (CCN)or ice nucleating particles (INPs). Airmass samples in Galveston, TX were surprisingly polluted with brief periods of ship emissions containing extremely high aerosol concentrations, at times exceeding 34,000 cm-3. These ship emission periods contained smaller, less hygroscopic particles than the background air, resulting in a 69% decline in the CCN activated fraction at 1% supersaturation. In comparison, continental airmass northwest of Houston contained an average aerosol concentration of 5200 cm-3, with low to moderate CCN activity. INPs may affect various cloud properties related to the formation, lifetime, and precipitation of deep convective clouds. Within the INP population in Greater Houston, supermicron particles were largely responsible for ice nucleation above -20°C, while submicron particles dominated below -20°C, as expected. The warmest nucleation temperatures coincided with the presence of potassium-rich feldspar, determined by Raman spectroscopy. This characterization of Greater Houston’s aerosol population can provide insight for weather and climate models.