Examining the Vertical Heterogeneity of Aerosols over the Southern Great Plains

YANG WANG, Chanakya Bagya Ramesh, Scott Giangrande, Jerome Fast, Xianda Gong, Jiaoshi Zhang, Alyssa Matthews, Fan Mei, John Shilling, Jason Tomlinson, Dié Wang, Jian Wang, University of Miami

     Abstract Number: 120
     Working Group: Remote and Regional Atmospheric Aerosol

Abstract
Both aerosol direct and indirect effects on climate are affected by the vertical distribution of aerosols in the atmosphere, which is influenced by a range of processes, such as aerosol dynamics, long-range transport, and entrainment. However, many observations of these processes are based on ground measurements, limiting our ability to understand the vertical distribution of aerosols and simulate their impact on clouds and climate. In this work, we examined the vertical heterogeneity of aerosols over the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) using data collected from the Holistic Interactions of Shallow Clouds, Aerosols and Land Ecosystems (HI-SCALE) campaign. Based on the 38 flight measurements during HI-SCALE, the aerosol properties over the SGP show strong vertical heterogeneity and seasonal variabilities. The aerosol concentrations at the surface are the highest due to strong sources of emission at ground level. The mode diameter of these aerosols during summer (~ 100 nm) is larger than that during spring (~ 30 nm), potentially as a result of enhanced condensational growth due to enriched volatile organic compounds in summer. In the BL, the size of the aerosols gradually increases with altitude due to condensational growth and cloud processing. Through the vertical profiles of aerosol properties, we noticed a considerable number of NPF events (7 out of 38) in the upper BL, where the newly formed particles continue to grow as they are mixed down to the surface. There is also an indication that deep convection brings aerosols from the free troposphere (FT) to the surface, where they grow to contribute to the cloud condensation nuclei (CCN). Overall, the vertical heterogeneity of aerosols over the SGP is influenced by aerosol dynamics (new particle formation, growth, and cloud processing) and transport processes (long-range transport, entrainment, and convective downward transport).