Trace gas composition in the Asian summer monsoon anticyclone: a case study based on aircraft observations and model simulations

Publikationstyp:
Zeitschriftenaufsatz
Metadaten:
Autoren
  • Klaus-D Gottschaldt
  • Hans Schlager
  • Robert Baumann
  • Heiko Bozem
  • Veronika Eyring
  • Peter Hoor
  • Patrick Joeckel
  • Tina Jurkat
  • Christiane Voigt
  • Andreas Zahn
  • Helmut Ziereis
Autoren-URL
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=fis-test-1&SrcAuth=WosAPI&KeyUT=WOS:000401432200007&DestLinkType=FullRecord&DestApp=WOS_CPL
DOI
10.5194/acp-17-6091-2017
eISSN
1680-7324
Externe Identifier
  • Clarivate Analytics Document Solution ID: EV0LT
ISSN
1680-7316
Ausgabe der Veröffentlichung
9
Zeitschrift
ATMOSPHERIC CHEMISTRY AND PHYSICS
Paginierung
6091 - 6111
Datum der Veröffentlichung
2017
Status
Published
Titel
Trace gas composition in the Asian summer monsoon anticyclone: a case study based on aircraft observations and model simulations
Sub types
  • Article
Ausgabe der Zeitschrift
17

Datenquelle: Web of Science (Lite)

Andere Metadatenquellen:
Abstract
<jats:p>Abstract. We present in situ measurements of the trace gas composition of the upper tropospheric (UT) Asian summer monsoon anticyclone (ASMA) performed with the High Altitude and Long Range Research Aircraft (HALO) in the frame of the Earth System Model Validation (ESMVal) campaign. Air masses with enhanced O3 mixing ratios were encountered after entering the ASMA at its southern edge at about 150 hPa on 18 September 2012. This is in contrast to the presumption that the anticyclone's interior is dominated by recently uplifted air with low O3 in the monsoon season. We also observed enhanced CO and HCl in the ASMA, which are tracers for boundary layer pollution and tropopause layer (TL) air or stratospheric in-mixing respectively. In addition, reactive nitrogen was enhanced in the ASMA. Along the HALO flight track across the ASMA boundary, strong gradients of these tracers separate anticyclonic from outside air. Lagrangian trajectory calculations using HYSPLIT show that HALO sampled a filament of UT air three times, which included air masses uplifted from the lower or mid-troposphere north of the Bay of Bengal. The trace gas gradients between UT and uplifted air masses were preserved during transport within a belt of streamlines fringing the central part of the anticyclone (fringe), but are smaller than the gradients across the ASMA boundary. Our data represent the first in situ observations across the southern part and downstream of the eastern ASMA flank. Back-trajectories starting at the flight track furthermore indicate that HALO transected the ASMA where it was just splitting into a Tibetan and an Iranian part. The O3-rich filament is diverted from the fringe towards the interior of the original anticyclone, and is at least partially bound to become part of the new Iranian eddy. A simulation with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model is found to reproduce the observations reasonably well. It shows that O3-rich air is entrained by the outer streamlines of the anticyclone at its eastern flank. Back-trajectories and increased HCl mixing ratios indicate that the entrained air originates in the stratospherically influenced TL. Photochemical ageing of air masses in the ASMA additionally increases O3 in originally O3-poor, but CO-rich air. Simulated monthly mean trace gas distributions show decreased O3 in the ASMA centre only at the 100 hPa level in July and August, but at lower altitudes and in September the ASMA is dominated by increased O3. The combination of entrainment from the tropopause region, photochemistry and dynamical instabilities can explain the in situ observations, and might have a larger impact on the highly variable trace gas composition of the anticyclone than previously thought.</jats:p>
Autoren
  • Klaus-D Gottschaldt
  • Hans Schlager
  • Robert Baumann
  • Heiko Bozem
  • Veronika Eyring
  • Peter Hoor
  • Patrick Jöckel
  • Tina Jurkat
  • Christiane Voigt
  • Andreas Zahn
  • Helmut Ziereis
DOI
10.5194/acp-17-6091-2017
eISSN
1680-7324
Ausgabe der Veröffentlichung
9
Zeitschrift
Atmospheric Chemistry and Physics
Sprache
en
Online publication date
2017
Paginierung
6091 - 6111
Status
Published online
Herausgeber
Copernicus GmbH
Herausgeber URL
http://dx.doi.org/10.5194/acp-17-6091-2017
Datum der Datenerfassung
2022
Titel
Trace gas composition in the Asian summer monsoon anticyclone: a case study based on aircraft observations and model simulations
Ausgabe der Zeitschrift
17

Datenquelle: Crossref

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