Japan Geoscience Union Meeting 2016

Presentation information


Symbol A (Atmospheric and Hydrospheric Sciences) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS11] Stratosphere-troposphere Processes And their Role in Climate

Mon. May 23, 2016 3:30 PM - 5:00 PM A01 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Yousuke Yamashita(National Institute for Environmental Studies), Hideharu Akiyoshi(National Institute for Environmental Studies), Kaoru Sato(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Yoshihiro Tomikawa(National Institute of Polar Research), Chair:Hideharu Akiyoshi(National Institute for Environmental Studies)

3:30 PM - 3:45 PM

[AAS11-13] Observational study of the short-lived ozone depleting substances, bromoform and dibromomethane

*Yoko Yokouchi1, Takuya Saito1, Jiye Zeng1, Hitoshi Mukai1, Stephen Montzka2 (1.National Institute for Environmental Studies, 2.National Oceanic and Atmospheric Administration)

Keywords:bromocarbons, sources, long-term observation

Bromoform (CHBr3) and dibromomethane (CH2Br2), which undergo photolytic degradation and react with OH to produce inorganic bromine, are the large contributors of organic bromine from the ocean to the atmosphere, where it can affect stratospheric and tropospheric ozone chemistry (Carpenter and Liss 2000; Montzka and Reimann 2011). These naturally produced ozone-depleting substances (ODS) are attracting more interest as concentrations of anthropogenic ODS decrease under the provisions of the Montreal Protocol. The major sources of these bromocarbons are believed to be seaweed or macroalgae, followed by phytoplankton and other biological sources, but many uncertainties remain with regard to their production amount and mechanism. In this study, we conducted high-frequency long-term measurements of CH2Br2 and CHBr3 at Hateruma Island, and found that the relationship between [CH2Br2]/[CHBr3] and [CHBr3] could be explained by their chemical decay in the atmosphere with a fairly consistent CH2Br2/CHBr3 initial emission ratio, and some additional coastal effects. By combining these data with NOAA global observation data (14-yr monthly data from 14 ground stations), we obtained new insight into the global sources of these bromocarbons and their chemical degradation.