In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 20, No. 20 ( 2020-10-22), p. 11869-11892
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.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-20-11869-2020
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2020
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
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