Journal Article

FZJ-2020-05050

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Aircraft‐based observations of ozone‐depleting substances in the upper troposphere and lower stratosphere in and above the Asian summer monsoon\

Adcock, K. E. (Corresponding author) ; Fraser, P. J. ; Hall, B. D. ; Langenfelds, R. L. ; Lee, G. ; Montzka, S. A. ; Oram, D. E. ; Röckmann, T. ; Stroh, F.FZJ* ; Sturges, W. T. ; Vogel, B.FZJ* ; Laube, J. C.FZJ*

2021
Wiley Hoboken, NJ

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Please use a persistent id in citations: http://hdl.handle.net/2128/26995  doi:10.1029/2020JD033137

Abstract: Recent studies show that the Asian Summer Monsoon Anticyclone (ASMA) transports emissions from the rapidly industrializing nations in Asia into the tropical upper troposphere. Here we present a unique set of measurements on over 100 air samples collected on multiple flights of the M55 Geophysika high altitude research aircraft over the Mediterranean, Nepal and northern India during the summers of 2016 and 2017 as part of the European Union project StratoClim. These air samples were measured for 27 ozone‐depleting substances (ODSs), many of which were enhanced above expected levels, including the chlorinated very short‐lived substances, dichloromethane (CH2Cl2), 1,2‐dichloroethane (CH2ClCH2Cl) and chloroform (CHCl3). CH2Cl2 mixing ratios in the tropopause region were 65‐136 ppt in comparison to previous estimates of mixing ratios in the tropical tropopause layer of 30‐44 ppt in 2013‐2014. Backward trajectories, calculated with the trajectory module of the chemistry‐transport model CLaMS and driven by the ERA5 reanalysis, indicate possible source regions of CH2Cl2 in South Asia. We derived total Equivalent Chlorine (ECl), and Equivalent Effective Stratospheric Chlorine (EESC) and found that these quantities were substantially higher than previous estimates in the literature. EESC at mean age‐of‐air of 3 years based on the 2016 measurements was 1861‐1872 ppt in comparison to a previously estimated EESC of 1646 ppt. Our findings show that the ASMA transports larger than expected mixing ratios of long‐lived and very short‐lived ODSs into the upper troposphere and lower stratosphere, likely leading to an impact on the stratospheric ozone layer.

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Contributing Institute(s):

1. Stratosphäre (IEK-7)

Research Program(s):

1. 2112 - Climate Feedbacks (POF4-211) (POF4-211)
2. STRATOCLIM - Stratospheric and upper tropospheric processes for better climate predictions (603557) (603557)
3. EXC3ITE - EXploring Chemistry, Composition and Circulation in the stratosphere with Innovative TEchnologies (678904) (678904)

Appears in the scientific report 2021

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; DEAL Wiley ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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