Long-term changes of the upper stratosphere as seen by Japanese rocketsondes at Ryori (39°N, 141°E) - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Annales Geophysicae Année : 1999

Long-term changes of the upper stratosphere as seen by Japanese rocketsondes at Ryori (39°N, 141°E)

Résumé

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.
Fichier principal
Vignette du fichier
angeo-17-1210-1999.pdf (233.29 Ko) Télécharger le fichier
Origine : Accord explicite pour ce dépôt
Loading...

Dates et versions

hal-00329137 , version 1 (18-06-2008)

Identifiants

  • HAL Id : hal-00329137 , version 1

Citer

Philippe Keckhut, K. Kodera. Long-term changes of the upper stratosphere as seen by Japanese rocketsondes at Ryori (39°N, 141°E). Annales Geophysicae, 1999, 17 (9), pp.1210-1217. ⟨hal-00329137⟩
79 Consultations
119 Téléchargements

Partager

Gmail Facebook X LinkedIn More