TY  - JOUR
A1  - Rauthe-Schöch, Armin
A1  - Baker, Angela
A1  - Schuck, Tanja J.
A1  - Brenninkmeijer, Carl
A1  - Zahn, Andreas
A1  - Hermann, Markus
A1  - Stratmann, Greta
A1  - Ziereis, Helmut
A1  - Velthoven, Peter F. J. van
A1  - Lelieveld, Jos
T1  - Trapping, chemistry and export of trace gases in the South Asian summer monsoon observed during CARIBIC flights in 2008
T2  - Atmospheric chemistry and physics. Discussions
N2  - The CARIBIC (Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container) passenger aircraft observatory performed in situ measurements at 10–12 km altitude in the South Asian summer monsoon anticyclone between June and September 2008. These measurements enable us to investigate this atmospheric region, which so far has mostly been observed from satellites, using the broad suite of trace gases and aerosols measured by CARIBIC. Elevated levels of a range of atmospheric pollutants were recorded e.g. carbon monoxide, total reactive nitrogen oxides, aerosol particles and several volatile organic compounds. The measurements provide detailed information about the chemical composition of air in different parts of the monsoon anticyclone, particularly of ozone precursors. While covering a range of 3500 km inside the monsoon anticyclone, CARIBIC observations show remarkable consistency, i.e. with regular latitudinal patterns of trace gases during the entire monsoon period. Trajectory calculations indicate that these air masses originated mainly from South Asia and Mainland Southeast Asia.
Using the CARIBIC trace gas and aerosol measurements in combination with the Lagrangian particle dispersion model FLEXPART we investigated the characteristics of monsoon outflow and the chemical evolution of air masses during transport. Estimated photochemical ages of the air were found to agree well with transport times from a source region east of 95 ° E. The photochemical ages of the air in the southern part of the monsoon anticyclone were consistently younger (less than 7 days) and the air masses mostly in an ozone forming chemical regime. In its northern part the air masses were older (up to 13 days) and had unclear ozone formation or destruction potential. Based on analysis of forward trajectories several receptor regions were identified. In addition to predominantly westward transport, we found evidence for efficient transport (within 10 days) to the Pacific and North America, particularly during June and September, and also of cross-tropopause exchange, which was strongest during June and July. Westward transport to Africa and further to the Mediterranean was the main pathway during July.
Y1  - 2015
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/41886
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-418866
UR  - http://www.atmos-chem-phys-discuss.net/15/6967/2015
SN  - 1680-7367
SN  - 1680-7375
N1  - © Author(s) 2015. CC Attribution 3.0 License.
VL  - 15
SP  - 6967
EP  - 7018
PB  - European Geosciences Union
CY  - Katlenburg-Lindau
ER  -