Measurement-based modeling of bromine chemistry at the Dead Sea boundary layer ? Part 2: The influence of NO₂ on bromine chemistry at mid-latitude areas

E. Tas (1, 2) , M. Peleg (1) , D. U. Pedersen (1) , V. Matveev (1) , A. P. Biazar (3) , M. Luria (1)

1 Institute of Earth Sciences
2 Atmospheric Chemistry Department [MPIC]
3 Earth System Science Center [Huntsville]

Understanding the interaction between anthropogenic air pollution and Reactive Halogen Species (RHS) activity has had only limited support of direct field measurements, due to the fact that past field measurements of RHS have been mainly performed in Polar Regions. The present paper investigates the interaction between NO₂ and Reactive Bromine Species (RBS) activity by model simulations based on extensive field measurements performed in the Dead Sea area, as described in a companion paper (Tas et al., 2006). The Dead Sea is an excellent natural laboratory for this investigation since elevated concentrations of BrO (up to more than 150 pptv) are frequently observed, while the average levels of NO₂ are around several ppb. The results of the present study show that under the chemical mechanisms that occur at the Dead Sea, higher levels of NO₂ lead to higher daily average concentrations of BrO_X, as a result of an increase in the rate of the heterogeneous decomposition of BrONO₂ that in turn causes an increase in the rate of the "Bromine Explosion" mechanism. The present study has shown that the influence of NO₂ on BrO_X production clearly reflects an enhancement of RBS activity caused by anthropogenic activity. However, above a certain threshold level of NO₂ (daily average mixing ratios of 0.2 ppbv during RBS activity), the daily average concentrations of BrO_X decrease for a further increase in the NO₂ concentrations.

Domaines: Océan, Atmosphère

E. Tas, M. Peleg, D. U. Pedersen, V. Matveev, A. P. Biazar, et al.. Measurement-based modeling of bromine chemistry at the Dead Sea boundary layer ? Part 2: The influence of NO₂ on bromine chemistry at mid-latitude areas. Atmospheric Chemistry and Physics Discussions, 2008, 8 (2), pp.7725-7753. ⟨hal-00303472⟩