First investigations of IO, BrO, and NO2 summer atmospheric levels at a coastal East Antarctic site using mode‐locked cavity enhanced absorption spectroscopy

IO, BrO, and NO2 were measured for the first time at Dumont d'Urville (East Antarctic coast) during summer 2011/2012 by using a near‐UV‐Visible laser spectrometer based on mode‐locked cavity‐enhanced absorption spectroscopy. IO mixing ratios ranged from the 2σ detection limit (0.04 pptv) up to 0.15 pptv. BrO remained close or below the detection limit (2 pptv) of the instrument. Daily averaged NO2 values ranged between the detection limit (10 pptv) and 60 pptv being far higher than levels of a few pptv commonly observed in the remote marine boundary layer. Data are discussed and compared with those available for another coastal Antarctic station (Halley, West Antarctica). It is shown that the oxidative capacity of the atmospheric boundary layer at coastal Antarctic sites is quite different in nature from West to East Antarctica, with the halogen chemistry being promoted at West and the OH chemistry at East.