Abstract:

Reactive halogen species in the atmosphere play a crucial role in tropospheric chemistry by destroying ozone and influencing aerosol composition and properties. However, the impact of reactive halogens—particularly iodine species—on the chemistry of the marine boundary layer remains poorly constrained due to limited observations over the open ocean and a lack of detailed chemical analysis.

In this seminar, I will discuss how we address this knowledge gap using an observation-driven modeling approach to provide a detailed understanding of the sources and chemistry of reactive iodine species. We measured iodine oxide, IO, using a long-path Differential Optical Absorption Spectroscopy (LP-DOAS) instrument during the Bermuda Boundary Layer Experiment on the Atmospheric Chemistry of Halogens (BLEACH) campaign conducted in Summer 2022 and Winter 2023. This data and observations by our collaborators were analyzed using the Platform for Atmospheric Chemistry and Transport in 1-Dimension (PACT-1D) model and an expanded gas and aqueous phase chemical mechanism. The model reveals how much iodine is released from the ocean via ozone deposition, provides new insight into the gas-aerosol partitioning, and elucidates the role of iodine chemistry in the ozone budget in the remote marine boundary layer.