Mixing and ageing in the polar lower stratosphere in winter 2015–2016
Mixing and ageing in the polar lower stratosphere in winter 2015–2016
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DOI：
10.5194/acp-18-6057-2018
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发表时间：
2017-10
影响因子：
6.3
通讯作者：
J. Krause;P. Hoor;A. Engel;F. Plöger;J. Grooß;H. Bönisch;T. Keber;B. Sinnhuber;W. Woiwode;H. Oelhaf
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文献类型：
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作者：
J. Krause;P. Hoor;A. Engel;F. Plöger;J. Grooß;H. Bönisch;T. Keber;B. Sinnhuber;W. Woiwode;H. Oelhaf
抽象。我们提供了2015-2016年冬季的数据，这些数据是在2015年12月至2016年3月期间在北极对流层上部和平流层下部（UTLS）的POLSTRACC（气候变化中的极地平流层）飞机活动期间测量的。这项工作的重点是运输和混合的作用之间的老化和潜在的化学处理的空气质量从平流层，具有中纬度和低纬度的空气质量分数与小过境时间起源于热带低平流层。通过结合CO，N2 O和SF 6的测量，我们估计的演变过程中的运输和混合的UTLS组成的相对贡献的冬季。我们发现，在北大西洋和欧洲北极地区，在Θ=360 K和Θ=410 K之间的平流层外低层和最低层，随着冬季的推移，N2 O和SF6值的下降表明，部分来自涡旋的老化平流层空气的影响越来越大。平流层低层CO相对于N2 O平均增加（3.00 ± 1.64）ppb V.我们表明，这种增加CO是一致的对流层空气的混合增加的快速传输机制的一部分，在平流层低冲浪区。分析的空气质量的部分影响，起源于热带对流层顶的空气质量，准水平混合到高纬度地区。对流层空气含量的增加部分地补偿了UTLS的老化，这是由于水平混合的对流层影响的空气质量从涡旋中非绝热下降造成的。这与平流层化学拉格朗日模型（CLaMS）模拟的年龄谱一致，该模型显示，在6个月以下的过境时间，对流层空气中相应的分数增加，同时增加来自平流层上部和涡旋区域的老化空气，过境时间超过2年。因此，我们得出结论，2015-2016年冬季平流层最低层受到来自平流层上部和涡旋区的老化空气的影响。这些气团受到来自低纬度地区的混合增加的显著影响，导致2016年1月至3月北极平流层最低层的年轻空气比例同时增加了6%。
Abstract. We present data from winter 2015–2016, which were measured during the POLSTRACC (The Polar Stratosphere in a Changing Climate) aircraft campaign between December 2015 and March 2016 in the Arctic upper troposphere and lower stratosphere (UTLS). The focus of this work is on the role of transport and mixing between aged and potentially chemically processed air masses from the stratosphere which have midlatitude and low-latitude air mass fractions with small transit times originating at the tropical lower stratosphere. By combining measurements of CO, N 2 O and SF 6 we estimate the evolution of the relative contributions of transport and mixing to the UTLS composition over the course of the winter. We find an increasing influence of aged stratospheric air partly from the vortex as indicated by decreasing N 2 O and SF 6 values over the course of the winter in the extratropical lower and lowermost stratosphere between Θ=360 K and Θ=410 K over the North Atlantic and the European Arctic. Surprisingly we also found a mean increase in CO of (3.00 ± 1.64) ppb V from January to March relative to N 2 O in the lower stratosphere. We show that this increase in CO is consistent with an increased mixing of tropospheric air as part of the fast transport mechanism in the lower stratosphere surf zone. The analysed air masses were partly affected by air masses which originated at the tropical tropopause and were quasi-horizontally mixed into higher latitudes. This increase in the tropospheric air fraction partly compensates for ageing of the UTLS due to the diabatic descent of air masses from the vortex by horizontally mixed, tropospheric-influenced air masses. This is consistent with simulated age spectra from the Chemical Lagrangian Model of the Stratosphere (CLaMS), which show a respective fractional increase in tropospheric air with transit times under 6 months and a simultaneous increase in aged air from upper stratospheric and vortex regions with transit times longer than 2 years. We thus conclude that the lowermost stratosphere in winter 2015–2016 was affected by aged air from the upper stratosphere and vortex region. These air masses were significantly affected by increased mixing from the lower latitudes, which led to a simultaneous increase in the fraction of young air in the lowermost Arctic stratosphere by 6 % from January to March 2016.