Observations of hydroxyl and peroxy radicals and the impact of BrO at Summit, Greenland in 2007 and 2008

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Liao, Jin, Huey, L., Tanner, Dave, Brough, Neil, Brooks, S., Dibb, Jack, Stutz, Jochen, Thomas, Jennie L, Lefer, Barry, Haman, C., Gorham, K.
• Other Authors: School of Earth and Atmospheric Sciences Atlanta, Georgia Institute of Technology Atlanta, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), NOAA Air Resources Laboratory (ARL), National Oceanic and Atmospheric Administration (NOAA), EOS Climate Change Research Center Durham, Institute for the Study of Earth, Oceans, and Space Durham (EOS), University of New Hampshire (UNH)-University of New Hampshire (UNH), Department of Atmospheric and Oceanic Sciences Los Angeles (AOS), University of California Los Angeles (UCLA), University of California (UC)-University of California (UC), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Geosciences Houston, University of Houston, Department of Chemistry Irvine, University of California Irvine (UC Irvine)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: [SDU]Sciences of the Universe [physics]; Greenland; Ice Sheet
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-03623465; https://hal-insu.archives-ouvertes.fr/insu-03623465/document; https://hal-insu.archives-ouvertes.fr/insu-03623465/file/acp-11-8577-2011.pdf; https://doi.org/10.5194/acp-11-8577-2011

International audience The Greenland Summit Halogen-HO x (GSHOX) Campaign was performed in spring 2007 and summer 2008 to investigate the impact of halogens on HO x (= OH + HO 2 ) cycling above the Greenland Ice Sheet. Chemical species including hydroxyl and peroxy radicals (OH and HO 2 + RO 2 ), ozone (O 3 ), nitrogen oxide (NO), nitric acid (HNO 3 ), nitrous acid (HONO), reactive gaseous mercury (RGM), and bromine oxide (BrO) were measured during the campaign. The median midday values of HO 2 + RO 2 and OH concentrations observed by chemical ionization mass spectrometry (CIMS) were 2.7 × 10 8 molec cm -3 and 3.0 × 10 6 molec cm -3 in spring 2007, and 4.2 × 10 8 molec cm -3 and 4.1 × 10 6 molec cm -3 in summer 2008. A basic photochemical 0-D box model highly constrained by observations of H 2 O, O 3 , CO, CH 4 , NO, and J values predicted HO 2 + RO 2 (R = 0.90, slope = 0.87 in 2007; R = 0.79, slope = 0.96 in 2008) reasonably well and under predicted OH (R = 0.83, slope = 0.72 in 2007; R = 0.76, slope = 0.54 in 2008). Constraining the model to HONO observations did not significantly improve the ratio of OH to HO 2 + RO 2 and the correlation between predictions and observations. Including bromine chemistry in the model constrained by observations of BrO improved the correlation between observed and predicted HO 2 + RO 2 and OH, and brought the average hourly OH and HO 2 + RO 2 predictions closer to the observations. These model comparisons confirmed our understanding of the dominant HO x sources and sinks in this environment and indicated that BrO impacted the OH levels at Summit. Although, significant discrepancies between observed and predicted OH could not be explained by the measured BrO. Finally, observations of enhanced RGM were found to be coincident with under prediction of OH.