Measurements of OH and RO₂ radicals at the coastal Antarctic site of Dumont d'Urville (East Antarctica) in summer 2010-2011

Alexandre Kukui (1) , Michel R. Legrand (2) , Gérard Ancellet (1) , Valérie Gros (3, 4) , Slimane Bekki (5) , Roland Sarda-Estève (3, 4) , Rodrigue Loisil (6) , Suzanne Preunkert (2)

1 TROPO - LATMOS
2 LGGE - Laboratoire de glaciologie et géophysique de l'environnement
3 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
4 CAE - Chimie Atmosphérique Expérimentale
5 STRATO - LATMOS
6 DTI - Division technique INSU/SDU

Measurements of OH and total proxy RO₂ (HO₂ plus organic peroxy) radicals were conducted in December 2010/January 2011 at the coastal East Antarctic site of Dumont d'Urville (DDU, 66°40'S 140°01'E) as part of the Oxidant Production over Antarctic Land and its Export (OPALE) project. Compared to measurements carried out at the West Antarctic coast, relatively high concentrations of radicals were found with 24 h average values of 2.1 × 10⁶ and 3.3 × 10⁸ molecule cm^-3 for OH and peroxy radicals, respectively. On the basis of the steady-state calculations, the observed high concentration of peroxy radicals is in good agreement with the observed levels of O₃ and HCHO representing via their photolysis the major primary radical sources. The observed OH levels at DDU could be explained only assuming some RO₂ to OH conversion mechanism equivalent to the presence of NO in the range of 10 to 50 pptv. As neither NO nor halogen oxides were measured at DDU the mechanism of this recycling could not be explicitly identified. However, an examination of variability of radical levels as a function of the origin (oceanic versus continental) of sampled air masses suggests a more important OH production from RO₂ recycling in continental air masses.

Mots clés: Antarctic photochemistry; Atmospheric oxidants; Hydroxyl radicals

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

Alexandre Kukui, Michel R. Legrand, Gérard Ancellet, Valérie Gros, Slimane Bekki, et al.. Measurements of OH and RO₂ radicals at the coastal Antarctic site of Dumont d'Urville (East Antarctica) in summer 2010-2011. Journal of Geophysical Research: Atmospheres, 2012, 117 (D12), pp.D12310. ⟨10.1029/2012JD017614⟩. ⟨hal-00705587⟩