Hossaini Ryan, Atlas Elliot, Dhomse Sandip S, Chipperfield Martyn P, Bernath Peter F, Fernando Anton M, Mühle Jens, Leeson Amber A, Montzka Stephen A, Feng Wuhu, Harrison Jeremy J, Krummel Paul, Vollmer Martin K, Reimann Stefan, O'Doherty Simon, Young Dickon, Maione Michela, Arduini Jgor, Lunder Chris R
Lancaster Environment Centre Lancaster University Lancaster UK.
Rosenstiel School of Marine and Atmospheric Science (RSMAS) University of Miami Coral Gables FL USA.
J Geophys Res Atmos. 2019 Feb 27;124(4):2318-2335. doi: 10.1029/2018JD029400. Epub 2019 Feb 16.
Very short-lived substances (VSLS), including dichloromethane (CHCl), chloroform (CHCl), perchloroethylene (CCl), and 1,2-dichloroethane (CHCl), are a stratospheric chlorine source and therefore contribute to ozone depletion. We quantify stratospheric chlorine trends from these VSLS (VSLCl) using a chemical transport model and atmospheric measurements, including novel high-altitude aircraft data from the NASA VIRGAS (2015) and POSIDON (2016) missions. We estimate VSLCl increased from 69 (±14) parts per trillion (ppt) Cl in 2000 to 111 (±22) ppt Cl in 2017, with >80% delivered to the stratosphere through source gas injection, and the remainder from product gases. The modeled evolution of chlorine source gas injection agrees well with historical aircraft data, which corroborate reported surface CHCl increases since the mid-2000s. The relative contribution of VSLS to total stratospheric chlorine increased from ~2% in 2000 to ~3.4% in 2017, reflecting both VSLS growth and decreases in long-lived halocarbons. We derive a mean VSLCl growth rate of 3.8 (±0.3) ppt Cl/year between 2004 and 2017, though year-to-year growth rates are variable and were small or negative in the period 2015-2017. Whether this is a transient effect, or longer-term stabilization, requires monitoring. In the upper stratosphere, the modeled rate of HCl decline (2004-2017) is -5.2% per decade with VSLS included, in good agreement to ACE satellite data (-4.8% per decade), and 15% slower than a model simulation without VSLS. Thus, VSLS have offset a portion of stratospheric chlorine reductions since the mid-2000s.
极短寿命物质（VSLS），包括二氯甲烷（CHCl）、氯仿（CHCl）、全氯乙烯（CCl）和1,2 - 二氯乙烷（CHCl），是平流层氯的一个来源，因此会导致臭氧消耗。我们使用化学传输模型和大气测量数据，包括来自美国国家航空航天局（NASA）的VIRGAS（2015年）和POSIDON（2016年）任务的新型高空飞机数据，来量化这些极短寿命物质产生的平流层氯趋势（VSLCl）。我们估计VSLCl从2000年的69（±14）万亿分之一（ppt）氯增加到2017年的111（±22）ppt氯，其中超过80%通过源气体注入进入平流层，其余来自产物气体。模拟的氯源气体注入演变与历史飞机数据吻合良好，这些数据证实了自21世纪中期以来报告的地表CHCl增加情况。极短寿命物质对平流层总氯的相对贡献从2000年的约2%增加到2017年的约3.4%，这既反映了极短寿命物质的增长，也反映了长寿命卤代烃的减少。我们得出2004年至2017年期间VSLCl的平均增长率为3.8（±0.3）ppt氯/年，不过逐年增长率是可变的，在2015 - 2017年期间较小或为负。这是一个暂时效应还是长期稳定情况，需要进行监测。在平流层上部，包含极短寿命物质时模拟的HCl下降速率（2004 - 2017年）为每十年 - 5.2%，与大气化学实验（ACE）卫星数据（每十年 - 4.8%）吻合良好，并且比不包含极短寿命物质的模型模拟慢15%。因此，自21世纪中期以来，极短寿命物质抵消了平流层氯减少的一部分。
