2025FICUS

FICUS: Quantifying the integrated terrestrial

1 October 2024 - 30 September 2026

Lead Scientist: Chongai Kuang

Observatory: AMF

The deployment of the ARM AMF3 to the Bankhead National Forest (BNF) in the southeastern U.S. provides novel opportunities to improve the understanding and model representation of the climate impacts of atmospheric boundary layer (ABL) aerosol, cloud, and land-atmosphere processes, and their two-way couplings, as the BNF atmospheric environment is strongly driven by the land-surface. However, these land-surface controls are complex and poorly understood. Improved climate predictability in the region requires improved mechanistic understanding of the role of surface energy and mass fluxes and their controls on ABL dynamics, convection, and aerosol spatial distributions, as well as the two-way interactions between plant physiology and aerosol processes mediated through changes in atmospheric radiation and the terrestrial emissions of primary biological aerosol particles (PBAP) and aerosol gas-phase precursors, including biogenic volatile organic compounds (BVOCs) from the vegetation and soil. In the forested environment of the BNF, the terrestrial controls on PBAP emission and on new particle formation (NPF) from the photochemical reaction of BVOCs are expected to play critical roles as aerosol sources in the ABL. However, these processes are poorly understood due to uncertainties, both in the underlying aerosol microphysical mechanisms and in the ABL dynamical controls on the vertical distribution of PBAPs and BVOCs. This vertical distribution further obscures characterization of terrestrial aerosol controls due to the simultaneous mixing and aerosol processing during vertical transport.

The proposed research aims to quantify the terrestrial controls on aerosol sources within the ABL by characterizing the vertical distribution of PBAPs, BVOCs, and the resulting NPF in the ABL above the forested BNF environment, and by connecting these profiles to measured seasonal fluxes to link forest functioning with aerosol dynamics. These vertically resolved measurements will then be combined with planned surface- and tower-based BNF observations of aerosol and atmospheric state, and integrated into a high-resolution land-atmosphere model system to provide a holistic surface-to-atmosphere understanding of the terrestrial controls on atmospheric aerosol.