Anthropogenic Bromoform at the Extratropical Tropopause
Yue Jia, Josefine Hahn, Birgit Quack, Edward R. Jones, Meghan Brehon, Susann Tegtmeier
Abstract
Abstract Bromoform (CHBr 3 ) contributes to stratospheric ozone depletion but is not regulated under the Montreal Protocol due to its short lifetime and large natural sources. Here, we show that anthropogenic sources contribute significantly to the amount of CHBr 3 transported into the Northern Hemisphere (NH) extratropical stratosphere. We present a new CHBr 3 emission inventory comprised of natural and anthropogenic sources, with the latter estimated from ship ballast, power plant cooling and desalination plant brine water. Including anthropogenic sources in the new inventory increases CHBr 3 emissions by up to 31.5% globally and 70.5% in the NH. In consequence, atmospheric CHBr 3 is also significantly higher, especially over the NH extratropics during boreal winter. Here anthropogenic sources enhance bromine at the tropopause by 0.9 ppt Br, thus doubling natural CHBr 3 abundances. For some latitudes, tropopause bromine increases by 2.4 ppt Br suggesting significant contributions of anthropogenic CHBr 3 to the NH lowermost stratosphere.