Long-term time series of Arctic tropospheric BrO derived from UV–VIS satellite remote sensing and its relation to first-year sea ice

Abstract

Abstract. Every polar spring, phenomena called bromine explosions occur over sea ice. These bromine explosions comprise photochemical heterogeneous chain reactions that release bromine molecules, Br2, to the troposphere and lead to tropospheric plumes of bromine monoxide, BrO. This autocatalytic mechanism depletes ozone, O3, in the boundary layer and troposphere and thereby changes the oxidizing capacity of the atmosphere. The phenomenon also leads to accelerated deposition of metals (e.g., Hg). In this study, we present a 22-year (1996 to 2017) consolidated and consistent tropospheric BrO dataset north of 70∘ N, derived from four different ultraviolet–visible (UV–VIS) satellite instruments (GOME, SCIAMACHY, GOME-2A and GOME-2B). The retrieval data products from the different sensors are compared during periods of overlap and show good agreement (correlations of 0.82–0.98 between the sensors). From our merged time series of tropospheric BrO vertical column densities (VCDs), we infer changes in the bromine explosions and thus an increase in the extent and magnitude of tropospheric BrO plumes during the period of Arctic warming. We determined an increasing trend of about 1.5 % of the tropospheric BrO VCDs per year during polar springs, while the size of the areas where enhanced tropospheric BrO VCDs can be found has increased about 896 km2 yr−1. We infer from comparisons and correlations with sea ice age data that the reported changes in the extent and magnitude of tropospheric BrO VCDs are moderately related to the increase in first-year ice extent in the Arctic north of 70∘ N, both temporally and spatially, with a correlation coefficient of 0.32. However, the BrO plumes and thus bromine explosions show significant variability, which also depends, apart from sea ice, on meteorological conditions.

Springtime nitrogen oxides and tropospheric ozone in Svalbard: results from the measurement station network

“…Similarly, Koo et al (2012) studied advection of the O 3 -depleted air masses and found that these events were driven by local or short-range (1 d) transport from the nearby region. A recent study of Bougoudis et al (2020) explored connection between firstyear sea ice and bromine explosion events. In spring (March, April, May) 2017, Arctic mean tropospheric BrO VCDs over sea ice were on the order of 4 × 10 13 molec.…”

“…In spring (March, April, May) 2017, Arctic mean tropospheric BrO VCDs over sea ice were on the order of 4 × 10 13 molec. cm −2 , and significant anomalies of tropospheric BrO VCDs were observed over the sea ice north of Svalbard at approximately 85 • N. In addition to the sea-ice conditions, the tropospheric BrO plume formation depends on various meteorological factors and the amount of blowing snow (Bougoudis et al, 2020). To investigate these processes, the weather regime approach presented in the current study may be applied together with the long-term BrO remote-sensing data and in situ measurements from the Arctic stations in further studies.…”

Ozone depletion events in the Arctic spring of 2019: a new modeling approach to bromine emissions

“…Additionally, the type of surface covered by snow may be an important factor. Snow covering first-year (FY) ice, ice freshly formed in the previous winter, was found to correlate with bromine producing sites (Simpson et al, 2007;Abbatt et al, 2012;Bougoudis et al, 2020) in contrast to multi-year (MY) ice. Despite that, bromine activation over MY ice was observed as well (Peterson et al, 2019).…”

“…Ozone depletion events (ODEs) commonly occur in the Arctic boundary layer during spring. The ozone mixing ratio is reduced from its background level of approximately 30-60 nmol mol −1 to possibly zero levels coinciding with an increase in the bromine concentrations (Oltmans, 1981;Bottenheim et al, 1986;Barrie et al, 1988;Hausmann and Platt, 1994;Wagner and Platt, 1998;Richter et al, 1998;Wagner et al, 2001;Frieß et al, 2004;Wagner et al, 2007;Helmig et al, 2012;Halfacre et al, 2014;Zhao et al, 2016;Blechschmidt et al, 2016;Seo et al, 2019Seo et al, , 2020Bougoudis et al, 2020). The ozone depletion is of special interest since ozone is a very important trace gas due to its role in air pollution and its high oxidation potential.…”

Implementation and Impacts of Surface and Blowing Snow Sources of Arctic Bromine Activation Within WRF‐Chem 4.1.1

“…( 2013 ) reported the photo‐chemical production of molecular bromine from surface snow using chemical ionization mass spectroscopy (CIMS) based on Arctic snow chamber experiments. It has also been shown that bromine activation correlates with the occurrence of first‐year sea ice (Bougoudis et al., 2020 ; Simpson, Carlson, et al., 2007 ), and that it can also occur over snow found on multi‐year sea ice (Peterson et al., 2019 ). These surfaces are similar in that both first year and multi year ice are usually snow covered.…”