Modeling the Sources and Chemistry of Polar Tropospheric Halogens (Cl, Br, and I) Using the CAM-Chem Global Chemistry-Climate Model

• Published in: Journal of Advances in Modeling Earth Systems
• Main Authors: Fernandez, R.P., Carmona-Balea, A., Cuevas, C.A., Barrera, J.A., Kinnison, D.E., Lamarque, J.F., Blaszczak-Boxe, C., Kim, K., Choi, W., Hay, T., Blechschmidt, A.M., Schönhardt, A., Burrows, J.P., Saiz-Lopez, A.
• Other Authors: European Commission, Consejo Superior de Investigaciones Científicas (España), National Center for Atmospheric Research (US), Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina), Agencia Nacional de Promoción Científica y Tecnológica (Argentina), Korea Polar Research Institute, University of Bremen, German Research Foundation, European Space Agency, SCOAP
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2019
• Subjects: Photodynamic therapy; Methyl aminolevulinate; Bowen’s disease; Antarctic; Arctic; Southern Ocean; The Antarctic; Antarc*; Antarctica; Korea Polar Research Institute; Sea ice
• Online Access: http://hdl.handle.net/10261/206452; https://doi.org/10.1029/2019MS001655

31 pags., 12 figs., 6 tabs. -- Open Access funded by Creative Commons Atribution Licence 4.0 Current chemistry climate models do not include polar emissions and chemistry of halogens. This work presents the first implementation of an interactive polar module into the very short-lived (VSL) halogen version of the Community Atmosphere Model with Chemistry (CAM-Chem) model. The polar module includes photochemical release of molecular bromine, chlorine, and interhalogens from the sea-ice surface, and brine diffusion of iodine biologically produced underneath and within porous sea-ice. It also includes heterogeneous recycling of inorganic halogen reservoirs deposited over fresh sea-ice surfaces and snow-covered regions. The polar emission of chlorine, bromine, and iodine reach approximately 32, 250, and 39 Gg/year for Antarctica and 33, 271, and 4 Gg/year for the Arctic, respectively, with a marked seasonal cycle mainly driven by sunlight and sea-ice coverage. Model results are validated against polar boundary layer measurements of ClO, BrO, and IO, and satellite BrO and IO columns. This validation includes satellite observations of IO over inner Antarctica for which an iodine “leapfrog” mechanism is proposed to transport active iodine from coastal source regions to the interior of the continent. The modeled chlorine and bromine polar sources represent up to 45% and 80% of the global biogenic VSL and VSL emissions, respectively, while the Antarctic sea-ice iodine flux is ~10 times larger than that from the Southern Ocean. We present the first estimate of the contribution of polar halogen emissions to the global tropospheric halogen budget. CAM-Chem includes now a complete representation of halogen sources and chemistry from pole-to-pole and from the Earth's surface up to the stratopause. This study has been funded by the European Research Council Executive Agency under the European Union′s Horizon 2020 Research and Innovation program (Project “ERC‐2016‐COG 726349 CLIMAHAL”) and supported by the Consejo Superior de Investigaciones Científicas (CSIC) of Spain. Computing resources, support, and data storage are provided and maintained by the Computational and Information System Laboratory from the National Center of Atmospheric Research (CISL,2017). R. P. F. would like to thank CONICET, ANPCyT (PICT 2015‐0714), UNCuyo (SeCTyP M032/3853), and UTN (PID 4920‐194/2018) for the financial support. Partial funding for this work was provided by the Korea Polar Research Institute (KOPRI) project (PE18200). The contributions of the University of Bremen have been supported by the State of Bremen, the German Research Foundation (DFG), the German Aerospace (DLR), and the European Space Agency (ESA). We gratefully acknowledge the funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) —Projektnummer 268020496—TRR 172, within the Transregional Collaborative Research Center “ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes,and Feedback Mechanisms (AC)3 ” in subproject C03 as well as the support by the University of Bremen Institutional Strategy Measure M8 in the framework of the DFG Excellence Initiative.