Vertical Profiles of Reactive Bromine near Utqiagvik and Interactions with Anthropogenic Pollution

Bromine chemistry is particularly important in the springtime Arctic boundary layer, as it is largely responsible for ozone depletion events and affects the oxidative capacity of the lower atmosphere. As climate change continues to have a larger impact on polar regions, the sources of reactive bromine and the chemistry and dynamics of the Arctic boundary layer will be greatly impacted. Increasing NOx emissions from oil/natural gas extraction in the Prudhoe Bay region will also impact this chemistry through interactions between NOx and halogens. Observations of these impacts are necessary to predict the effects of a warming atmosphere, changing sea ice, and anthropogenic emissions on the regional atmosphere.

We present data gathered from the Heidelberg Airborne Imaging DOAS Instrument (HAIDI) deployed during the CHemistry in the Arctic: Clouds, Halogens, and Aerosols (CHACHA) field campaign in/around Utqiagvik, AK during spring of 2022. HAIDI was installed onboard the Purdue Airborne Laboratory for Atmospheric Research (ALAR), and the two UV-Vis spectrometers were used to observe BrO, NO2­, and O4 via four near-limb forward-viewing channels and one near-nadir whiskbroom mapper.

Through 24 research flights and in conjunction with a novel measurement approach, HAIDI/ALAR recorded several hundred profiles of BrO and NO2 in the Arctic boundary layer under an array of conditions. Optimal estimation retrievals reveal low BrO concentrations in air masses impacted by Prudhoe Bay emissions. High resolution nadir mapping from 10 research flights upwind, over, and downwind of fossil fuel facilities in the region also provides an unprecedented picture of emissions and their chemical impacts. These observations show a clear relationship between BrO and NO­2 columns near Prudhoe Bay, with a Pearson correlation coefficient as low as -0.78. These observations provide insight into the impacts of a changing and developing Arctic on atmospheric pollution and processing.