Special issue  

The OPALE (Oxidant Production over Antarctica Land and its Export) project aims to quantify, understand, and model the level of oxidants present in the lower atmosphere of Antarctica. The oxidants are very abundant there in relation to the presence of large snow- and ice-covered areas. Previous studies focused on oxidants present in the lower atmosphere at the South Pole and at several coastal sites located in West Antarctica. Based on atmospheric measurements carried out at the Concordia (DC) station located at 3250m elevation on the high Antarctic plateau and at the coastal site of Dumont d’Urville (DDU), the project focuses on oxidants present over the eastern part of the Antarctic continent. The obtained data would be of great interest for the scientific communities working on numerous aspects of the global change (coupling atmosphere–ice–climate, interpretation of deep ice cores mainly drilled in East Antarctica, atmospheric chemistry over snow-covered regions).

Atmospheric measurements carried out at DDU and DC included HO_x radicals, chemical species controlling the radical productions (O₃, HONO, H₂O₂, HCHO, NO, and NO₂), and an isotopic approach to highlight oxidation mechanisms. The field data obtained during the two field campaigns are used to do the following:

• examine the levels of oxidants over the high Antarctic plateau and factors controlling their budgets;
• evaluate the impact of this very oxidizing boundary layer at coastal regions of East Antarctica on the basis of in situ observations and chemistry-transport model simulations.