Abstract
Abstract. Understanding the interaction between anthropogenic air pollution and Reactive Halogen Species (RHS) activity has had only limited support from 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 mixing ratios 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 mixing ratios of BrOx. This is the result of an increase in the rate of the heterogeneous decomposition of BrONO2, which in turn causes an increase in the rate of the "Bromine Explosion" mechanism. However, above a certain threshold level of NO2 (daily average mixing ratios of 0.2 ppbv during RBS activity), the daily average mixing ratios of BrOx decrease for a further increase in the NO2 mixing ratios. This investigation shows that the influence of NO2 on BrOx production clearly reflects an enhancement of RBS activity caused by anthropogenic activity.
Highlights
The destruction of ozone in the tropospheric boundary layer of Polar Regions by Reactive Halogen Species (RHS=X, XO, XnOm, HOx, X2, XY (X,Y=F,Cl, Br, I)) has been well documented during the last two decades
It has been shown that activity of Reactive Bromine Species (RBS=Br, BrO, BrnOm, HOBr, Br2), with BrO levels up to ∼30 ppt, play a major factor in boundary layer ozone depletion events (ODE’s) (Platt and Hoenninger, 2003)
The role of NO is not discussed because the NO levels measured during the field campaigns were usually very low, and frequently dropped below the detection limit (0.1 ppbv) during RBS activity
Summary
The destruction of ozone in the tropospheric boundary layer of Polar Regions by Reactive Halogen Species (RHS=X, XO, XnOm, HOx, X2, XY (X,Y=F,Cl, Br, I)) has been well documented during the last two decades (e.g., see Simpson et al, 2007 for an overview). It has recently been recognized that RBS may lead to ozone destruction in the boundary layer at mid-latitude areas This was evident for the first time at the Dead Sea where very high BrO levels, above 150 ppt, were detected together with daytime depletion of O3 from levels of above 120 ppb to below the detection limit of the instrument (
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
