1 research outputs found
Multiphase Reactive Bromine Chemistry during Late Spring in the Arctic: Measurements of Gases, Particles, and Snow
Bromine
radicals (Br路) cause ozone depletion and
mercury deposition
in the Arctic atmospheric boundary layer, following Polar sunrise.
These Br radicals are primarily formed by the photolysis of molecular
bromine (Br2), which is photochemically produced in the
snowpack. Recently, it was shown that bromine monoxide (BrO路),
formed from the reaction of Br路 with ozone, is episodically present
until the onset of snowmelt in late Arctic spring. To examine the
drivers of this late spring shutdown of reactive bromine chemistry,
the gases Br2, HOBr, BrO, and BrCl were continuously monitored
using chemical ionization mass spectrometry during the spring (March鈥揗ay
2016) near Utqiag虈vik, Alaska. On May 10th, all four reactive
bromine species fell below levels of detection at the same time that
air temperature increased above 0 掳C, surface albedo decreased,
and snowmelt onset was observed. Prior to the cessation of atmospheric
bromine chemistry, local surface snow samples in early May became
significantly enriched in bromide, likely due to the slowdown of reactive
bromine recycling with continued deposition but decreased emissions
from the snowpack. Particulate bromide concentrations were not sufficient
to explain the quantities of reactive bromine gases observed and decreased
upon snowmelt. Low wind speeds during the weeks preceding the cessation
of reactive bromine chemistry point to the lack of a contribution
to bromine chemistry from blowing snow. Together, these results further
highlight the significance of the surface snowpack in multiphase bromine
recycling with important implications as the melt season arrives earlier
due to climate change