Transport timescales and halogen budget in the Arctic polar Vortex and the UTLS during HALO-ASCCI

ASCCI项目是北半球极地冬末至早春的HALO任务，旨在研究北极最下层平流层和对流层上层的臭氧。ASCCI活动的科学背景在同一申请人（Andreas Engel）和Björn-Martin Sinnhuber （KIT Karlsruhe）的活动协调提案中进行了描述。在这里，我们特别关注与法兰克福大学提出的与ASCCI运动相关的工作方面。法兰克福大学拥有一台带有电子捕获（GC-ECD）和质谱（GC-MS）检测的原位气相色谱仪。该仪器能够使用电子冲击（EI）和负化学电离（NCI）以及平均年龄示踪剂SF6测量广泛的卤化碳。我们关注与卤代烃相关的方面，它们在大气中的分布，大气中的总卤素负荷，平流层中的可用氯和溴，以及空气的平均年龄，特别是在ASCCI期间要调查的极地冬季条件。我们将在本提案中解决的主要研究问题是：与2015/2016年冬季进行的最后一次HALO极地冬季活动相比，大气氯预算发生了怎样的变化？-大气溴预算与2015/2016年冬季进行的最后一次HALO北极冬季活动相比有何变化-使用一种新的改进方法确定平流层下层的典型运输时间（平均空气年龄）是多少？-氯和溴的收支和平均年龄与南半球的分布相比如何，特别是如果数据在漩涡相对坐标系中进行比较？

The project ASCCI is a HALO mission in the Northern Hemisphere polar late winter to early spring to study ozone in the Arctic lowermost stratosphere and upper troposphere. The scientific background of the ASCCI campaign is described in the campaign co-ordination proposal by the same applicant (Andreas Engel) and Björn-Martin Sinnhuber (KIT Karlsruhe). Here we focus specifically on aspects related to the work proposed at University Frankfurt in relation to the ASCCI campaign. University Frankfurt operates an in-situ gas chromatograph with electron capture (GC-ECD) and with mass spectrometric (GC-MS) detection. The instrument is capable of measuring a wide suite of halocarbons, using both Electron Impact (EI) and Negative Chemical Ionization (NCI), and also the mean age tracer SF6. We focus on aspects related to halocarbons, their atmospheric distribution, on total halogen loading of the atmosphere, available chlorine and bromine in the stratosphere and on aspects of mean age of air, specifically for the polar winter conditions to be investigated during ASCCI. The main research question we will adress within this proosal are: - how has the atmospheric chlorine budget chenged in comparison to the winter 2015/2016 when the last Arctic polar winter campaign with HALO was performed. - how has the atmospheric bromine budget chenged in comparison to the winter 2015/2016 when the last Arctic polar winter campaign with HALO was performed - what are typical transport times (mean age of air) in the lower stratosphere using a new and improved method to determine mean age? - How do chlroine and bromine budgets and also mean age compare to the Southern Hemisphere distributions, in particular if data are comared in a vortex-relative coordinate system?