Long-term (2015-2023) observations of tropospheric BrO from two research sites in Antarctica

Reactive halogens compounds (i.e., those containing bromine, iodine, chlorine) are known to be key species for the oxidizing capacity of the atmosphere affecting e.g. the lifetime of relevant species such ozone, HOx or NOx and also to have an impact on the climate through interactions with other trace gases and aerosols.In the polar regions reactive halogens play a particular role since e.g. the auto-catalytic release of bromine from sea ice into the atmosphere may lead to the depletion of tropospheric ozone even below instrumental detection limit and, also, to the deposition of toxic mercury into the polar ecosystem.In order to infer vertical profiles of relevant tropospheric trace gases, within the framework of several nationally funded projects (including the current GARDENIA project) and in collaboration with the Argentinian National Antarctic Direction, INTA has being performing multi-axis DOAS (MAXDOAS) observations from Antarctica for nearly a decade. One of the gases retrieved through the MAXDOAS technique is bromine monoxide (BrO), a reactive form of bromine.The work presented herein expands the 1-year study of Prados-Roman et al. (2018) to a 8-year study of the presence of tropospheric BrO at two research sites in Antarctica: Belgano II (77°52' S, 34°7' W) and Marambio (64°13' S, 56°37' W). We will present tropospheric BrO data from the two research sites that expands from 2015 to last year 2023, with values as high as nearly 40 pmol/mol. We will discuss the tropospheric BrO vertical and  latitudinal distribution as well its seasonal evolution throughout all these years.Note that a similar work but based on observations of iodine monoxide from Antarctica will be presented at EGU2024 in the work of Puentedura et al. (2024).