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| Titel |
Transport of mesospheric H2O during and after the stratospheric sudden warming of January 2010: observation and simulation |
| VerfasserIn |
C. Straub, B. Tschanz, K. Hocke, N. Kämpfer, A. K. Smith |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 12 ; Nr. 12, no. 12 (2012-06-22), S.5413-5427 |
| Datensatznummer |
250011277
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| Publikation (Nr.) |
 copernicus.org/acp-12-5413-2012.pdf |
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| Zusammenfassung |
The transportable ground based microwave radiometer MIAWARA-C monitored the
upper stratospheric and lower mesospheric (USLM) water vapor distribution
over Sodankylä, Finland (67.4° N, 26.6° E) from January
to June 2010. At the end of January, approximately 2 weeks after MIAWARA-C's
start of operation in Finland, a stratospheric sudden warming (SSW) disturbed
the circulation of the middle atmosphere. Shortly after the onset of the SSW
water vapor rapidly increased at pressures between 1 and 0.01 hPa. Backward
trajectory calculations show that this strong increase is due to the
breakdown of the polar vortex and meridional advection of subtropical air to
the Arctic USLM region. In addition, mesospheric upwelling in the course of
the SSW led to an increase in observed water vapor between 0.1 and 0.03 hPa.
After the SSW MIAWARA-C observed a decrease in mesospheric water vapor volume
mixing ratio (VMR) due to the subsidence of H2O poor air masses in the
polar region. Backward trajectory analysis and the zonal mean water vapor
distribution from the Microwave Limb Sounder on the Aura satellite (Aura/MLS)
indicate the occurrence of two regimes of circulation from 50° N to
the North Pole: (1) regime of enhanced meridional mixing throughout February
and (2) regime of an eastward circulation in the USLM region reestablished
between early March and the equinox. The polar descent rate determined from
MIAWARA-C's 5.2 parts per million volume (ppmv) isopleth is
350 ± 40 m d−1 in the pressure range 0.6 to 0.06 hPa between early
February and early March. For the same time interval the descent rate in the
same pressure range was determined using Transformed Eulerian Mean (TEM) wind
fields simulated by means of the Whole Atmosphere Community Climate Model
with Specified Dynamics (SD-WACCM). The average value of the SD-WACCM TEM
vertical wind is 325 m d−1 while the along trajectory vertical
displacement is 335 m d−1. The similar descent rates found indicate
good agreement between the model and MIAWARA-C's measurements. |
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