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| Titel |
Long-term changes of the upper stratosphere as seen by Japanese rocketsondes at Ryori (39°N, 141°E) |
| VerfasserIn |
P. Keckhut, K. Kodera |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 17, no. 9 ; Nr. 17, no. 9, S.1210-1217 |
| Datensatznummer |
250013813
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| Publikation (Nr.) |
 copernicus.org/angeo-17-1210-1999.pdf |
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| Zusammenfassung |
Wind and temperature profiles measured
routinely by rockets at Ryori (Japan) since 1970 are analysed to quantify
interannual changes that occur in the upper stratosphere. The analysis involved
using a least square fitting of the data with a multiparametric adaptative model
composed of a linear combination of some functions that represent the main
expected climate forcing responses of the stratosphere. These functions are
seasonal cycles, solar activity changes, stratospheric optical depth induced by
volcanic aerosols, equatorial wind oscillations and a possible linear trend.
Step functions are also included in the analyses to take into account
instrumental changes. Results reveal a small change for wind data series above
45 km when new corrections were introduced to take into account instrumental
changes. However, no significant change of the mean is noted for temperature
even after sondes were improved. While wind series reveal no significant trends,
a significant cooling of 2.0 to 2.5 K/decade is observed in the mid upper
stratosphere using this analysis method. This cooling is more than double the
cooling predicted by models by a factor of more than two. In winter, it may be
noted that the amplitude of the atmospheric response is enhanced. This is
probably caused by the larger ozone depletion and/or by some dynamical feedback
effects. In winter, cooling tends to be smaller around 40-45 km (in fact a
warming trend is observed in December) as already observed in other data sets
and simulated by models. Although the winter response to volcanic aerosols is in
good agreement with numerical simulations, the solar signature is of the
opposite sign to that expected. This is not understood, but it has already been
observed with other data sets.
Key words. Atmospheric composition and structure
(evolution of one atmosphere; pressure · density · and temperature) ·
Meteorology and atmospheric dynamics (middle atmosphere dynamics) |
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