Radiosondes stratospheric temperatures from 1957 to 2008 at Dumont d'Urville (Antarctica): trends and link with Polar Stratospheric Clouds

Abstract

Abstract. Temperature profiles measurements are performed daily (00:00 UT) in Dumont d'Urville by Météo-France, using standard radiosondes, since the International Geophysical Year in 1957. A significant cooling of about 2.3 K/decade at 20 km appears between 1957 and 2008, consistent with other Antarctic studies. Due to a 16 years data gap between 1963 and 1978, only the most recent series, between 1979 and 2008, is used to investigate the inter-annual stratospheric temperatures variability. Over Dumont d'Urville, at the edge of the vortex, the annual mean temperature cooling of about 1 K/decade is the result of the cooling trends between 0.5 and 1.4 K/decade, in summer and autumn and a warming of about 1.1 K/decade in spring. These values are consistent with values obtained using data from inner vortex stations, but with smaller amplitude. No statistically significant trend is detected in winter. Despite the absence of mean temperature trend during winter, the occurrence of temperatures below the NAT threshold, between 1989 and 2008, reveals a significant trend of about +6%/decade. The PSCs occurrences frequency exhibits a concomitant trend of about +3%/decade, although not statistically significant. Yet, this is consistent with results obtained in the Northern Hemisphere. Such a possible positive trend in PSC occurrence has to be further explored to be confirmed or invalidated.

Contribution of stratospheric warmings to temperature trends in the middle atmosphere from the lidar series obtained at Haute‐Provence Observatory (44°N)

“… Nishizawa and Yoden [2005] show that more detailed distribution analyses could improve trend estimates and are helpful to separate the different causes of variability. It is particularly applicable when threshold mechanisms are concerned like polar clouds formation [ David et al , 2009], or with the occurrence of extreme or rare events.…”

Refroidissement de la stratosphère : Détection réussie mais quantification encore incertaine

“…Cependant, ces effets ne sont pas linéaires et dépendent des interactions entre ondes planétaires et circulation moyenne (avec parfois l'apparition de réchauffements stratosphériques soudains dans l'hémisphère Nord). Les études récentes à partir des données journalières montrent qu'il est possible de rendre compte de ces effets à partir d'analyses statistiques basées sur la distribution des observations plutôt que la traditionnelle moyenne (David et al, 2010 ;Angot et al, 2012).…”