The Impact of the South Asia High Bimodality on the Chemical Composition of the Upper Troposphere and Lower Stratosphere

The South Asia High （SAH） is the dominant feature of the circulation in the upper troposphere and lower stratosphere （UTLS） during the boreal summer, and the upper tropospheric anticyclonic circulation extends into the lower stratosphere. The preferred locations of the center of the SAH occur in two...

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Published in:Atmospheric and oceanic science letters = Daqi-he-haiyang-kexue-kuaibao 2011, Vol.4 (4), p.229-234
Main Author: YAN Ren-Chang BIAN Jian-Chun FAN Qiu-Jun
Format: Article
Language:English
Subjects:
bimodality
Carbon monoxide
chemical composition
Chemical speciation
Distribution
Ozone
Plateaus
Pollution monitoring
SAH
Stratosphere
Temperature
Temperature fields
Tracers
Tropopause
Troposphere
UTLS
Water vapor
Water vapour
伊朗高原
低平流层
化学成分
化学物质
南亚高压
对流层顶
蛛网膜下腔
青藏高原
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Summary:The South Asia High （SAH） is the dominant feature of the circulation in the upper troposphere and lower stratosphere （UTLS） during the boreal summer, and the upper tropospheric anticyclonic circulation extends into the lower stratosphere. The preferred locations of the center of the SAH occur in two different regions, and the center can be located over the Iranian Plateau or over the Tibetan Plateau. This bimodality has an impact on the distribution of chemical constituents in the UTLS region. We analyzed water vapor （H20）, carbon monoxide （CO）, and ozone （03） data derived from the Aura Microwave Limb Sounder （MLS） and total column ozone data from the Ozone Monitoring Instrument （OMI）. For the Iranian Plateau mode of the SAH, the tropospheric tracers exhibited a positive anomaly over the Iranian Plateau and a negative anomaly over the Tibetan Plateau, whereas the stratospheric tracer exhibited a negative and a positive anomaly over the Iranian Plateau and the Tibetan Plateau, respectively. For the Tibetan Plateau mode, however, the distribution of the anomaly was the reverse of that found for the chemical species in the UTLS region. Furthermore, the locations of the extrema within the anomaly seemed to differ across chemical species. The anomaly extrema for H20 occurred in the vicinity of the SAH ridgeline, whereas CO and O3 exhibited a northward shift of 4-8 degrees. These impacts of the variation in the SAH on the chemical constitutes in the UTLS region can be attributed in part to the dynamical structure delineated by the tropopause field and the temperature field at 100 hPa.
ISSN:1674-2834
2376-6123
DOI:10.1080/16742834.2011.11446934