Observations of OH and HO2 radicals in coastal Antarctica

• Main Authors: S. J.-B. Bauguitte, H. K. Roscoe, D. E. Heard, R. A. Salmon, J. D. Lee, W. J. Bloss, A. E. Jones
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2007
• Subjects: Physics; QC1-999; Chemistry; QD1-999; Antarctic; Austral; Halley Research Station; Antarc*; Antarctica
• Online Access: https://doaj.org/article/283beb54234340a28b918dfde3835868

OH and HO 2 radical concentrations have been measured in the boundary layer of coastal Antarctica for a six-week period during the austral summer of 2005. The measurements were performed at the British Antarctic Survey's Halley Research Station (75° 35' S, 26° 19' W), using the technique of on-resonance laser-induced fluorescence to detect OH, with HO 2 measured following chemical conversion through addition of NO. The mean radical levels were 3.9×10 5 molecule cm −3 for OH, and 0.76 ppt for HO 2 (ppt denotes parts per trillion, by volume). Typical maximum (local noontime) levels were 7.9×10 5 molecule cm −3 and 1.50 ppt for OH and HO 2 respectively. The main sources of HO x were photolysis of O 3 and HCHO, with potentially important but uncertain contributions from HONO and higher aldehydes. Of the measured OH sinks, reaction with CO and CH 4 dominated, however comparison of the observed OH concentrations with those calculated via the steady state approximation indicated that additional co-reactants were likely to have been present. Elevated levels of NO x resulting from snowpack photochemistry contributed to HO x cycling and enhanced levels of OH, however the halogen oxides IO and BrO dominated the CH 3 O 2 – HO 2 – OH conversion in this environment, with associated ozone destruction.