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Title: The Role of Snow in Controlling Halogen Chemistry and Boundary Layer Oxidation During Arctic Spring: A 1D Modeling Case Study
Abstract

Reactive chlorine and bromine species emitted from snow and aerosols can significantly alter the oxidative capacity of the polar boundary layer. However, halogen production mechanisms from snow remain highly uncertain, making it difficult for most models to include descriptions of halogen snow emissions and to understand the impact on atmospheric chemistry. We investigate the influence of Arctic halogen emissions from snow on boundary layer oxidation processes using a one‐dimensional atmospheric chemistry and transport model (PACT‐1D). To understand the combined impact of snow emissions and boundary layer dynamics on atmospheric chemistry, we model Cl2and Br2primary emissions from snow and include heterogeneous recycling of halogens on both snow and aerosols. We focus on a 2‐day case study from the 2009 Ocean‐Atmosphere‐Sea Ice‐Snowpack campaign at Utqiaġvik, Alaska. The model reproduces both the diurnal cycle and high quantity of Cl2observed, along with the measured concentrations of Br2, BrO, and HOBr. Due to the combined effects of emissions, recycling, vertical mixing, and atmospheric chemistry, reactive chlorine is typically confined to the lowest 15 m of the atmosphere, while bromine can impact chemistry up to and above the surface inversion height. Upon including halogen emissions and recycling, the concentration of HOx(HOx = OH + HO2) at the surface increases by as much as a factor of 30 at mid‐day. The change in HOxdue to halogen chemistry, as well as chlorine atoms derived from snow emissions, significantly reduce volatile organic compound lifetimes within a shallow layer near the surface.

 
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NSF-PAR ID:
10369998
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Journal of Geophysical Research: Atmospheres
Volume:
127
Issue:
5
ISSN:
2169-897X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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