Recent Northern Hemisphere stratospheric HCl increase due to atmospheric circulation changes

E. Mahieu, M. P. Chipperfield, J. Notholt, T. Reddmann, J. Anderson, P. F. Bernath, T. Blumenstock, M. T. Coffey, S. S. Dhomse, W. Feng, B. Franco, L. Froidevaux, D. W.T. Griffith, J. W. Hannigan, F. Hase, R. Hossaini, N. B. Jones, I. Morino, I. Murata, H. NakajimaM. Palm, C. Paton-Walsh, J. M. Russell, M. Schneider, C. Servais, D. Smale, K. A. Walker

研究成果: ジャーナルへの寄稿学術論文査読

89 被引用数 (Scopus)

抄録

The abundance of chlorine in the Earth's atmosphere increased considerably during the 1970s to 1990s, following large emissions of anthropogenic long-lived chlorine-containing source gases, notably the chlorofluorocarbons. The chemical inertness of chlorofluorocarbons allows their transport and mixing throughout the troposphere on a global scale, before they reach the stratosphere where they release chlorine atoms that cause ozone depletion. The large ozone loss over Antarctica was the key observation that stimulated the definition and signing in 1987 of the Montreal Protocol, an international treaty establishing a schedule to reduce the production of the major chlorine- and bromine-containing halocarbons. Owing to its implementation, the near-surface total chlorine concentration showed a maximum in 1993, followed by a decrease of half a per cent to one per cent per year, in line with expectations. Remote-sensing data have revealed a peak in stratospheric chlorine after 1996, then a decrease of close to one per cent per year, in agreement with the surface observations of the chlorine source gases and model calculations. Here we present ground-based and satellite data that show a recent and significant increase, at the 2σ level, in hydrogen chloride (HCl), the main stratospheric chlorine reservoir, starting around 2007 in the lower stratosphere of the Northern Hemisphere, in contrast with the ongoing monotonic decrease of near-surface source gases. Using model simulations, we attribute this trend anomaly to a slowdown in the Northern Hemisphere atmospheric circulation, occurring over several consecutive years, transporting more aged air to the lower stratosphere, and characterized by a larger relative conversion of source gases to HCl. This short-term dynamical variability will also affect other stratospheric tracers and needs to be accounted for when studying the evolution of the stratospheric ozone layer.

本文言語英語
ページ(範囲)104-107
ページ数4
ジャーナルNature
515
7525
DOI
出版ステータス出版済み - 2014 11月 6

フィンガープリント

「Recent Northern Hemisphere stratospheric HCl increase due to atmospheric circulation changes」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル