Observations of OH and HO 2 radicals in coastal Antarctica
International audience 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'...
Main Authors: | , , , , , , |
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Other Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2007
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Subjects: | |
Online Access: | https://hal.science/hal-00302613 https://hal.science/hal-00302613/document https://hal.science/hal-00302613/file/acpd-7-2893-2007.pdf |
Summary: | International audience 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 or pmol mol ?1 ). 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. |
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