Nighttime chlorine monoxide observations by the Odin satellite and implications for the ClO/Cl2O2 equilibrium

• Published in: Geophysical Research Letters
• Main Authors: Berthet, Gwenaël, Ricaud, Pierre, Lefèvre, Franck, Le Flochmoën, E., Urban, Jakub, Barret, Brice, Lautie, N., Dupuy, E., de La Noe, J., Murtagh, D.
• Other Authors: Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge UK (CAM), Service d'aéronomie (SA), 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), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Department of Radio and Space Science Göteborg, Chalmers University of Technology Göteborg, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux Pessac (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Swedish National Space Board; Canadian Space Agency; National Technology Agency of Finland; Centre National d'Etudes Spatiales
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2005
• Subjects: Atmosphère moyenne; Composition chimique; Chimie atmosphérique; Mesure satellitaire; [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]; [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; Arctic
• Online Access: https://hal.science/hal-00069338; https://hal.science/hal-00069338/document; https://hal.science/hal-00069338/file/Berthet_et_al-2005-Geophysical_Research_Letters.pdf; https://doi.org/10.1029/2005GL022649

We use measurements of chlorine monoxide (ClO) by the SMR instrument onboard the Odin satellite to study the nighttime thermal equilibrium between ClO and its dimer Cl2O2. Observations performed in the polar vortex during the 2002–2003 Arctic winter showed enhanced amounts of nighttime ClO over a wide range of stratospheric temperatures (185 < T < 225 K). Odin/SMR measurements are here compared to three-dimensional model calculations using various published estimations of the Keq equilibrium constant between ClO and Cl2O2. Our results show that the value of Keq currently recommended by JPL (Sander et al., 2003) leads to a large underestimation of the observed nighttime ClO amounts, and that a realistic estimation of Keq must lie between the values determined by Cox and Hayman (1988) and Von Hobe et al. (2005).