Planetary-scale tropopause folds in the southern subtropics

Jean-Luc Baray (1) , V. Daniel (2) , Gérard Ancellet (3) , Bernard Legras (2)

1 LPA - Laboratoire de physique de l'atmosphère
2 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
3 SA - Service d'aéronomie

Daily measurements of tropospheric ozone at La Reunion Island (55 E, 21 S) in July 1998 show that ozone layers are quasi-permanent in the troposphere between 6 and 10 km with values reaching 80 to 100 ppbv. Meridional cross sections of potential vorticity reveal that these layers are related to tropopause folds beneath the subtropical jet. Folding is persistent and extends over a considerable longitude range from mid-Atlantic to mid-Pacific. We suggest that this structure is due to the convergent flow associated to the descent branch of the Hadley circulation during aus-tral winter.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]; Océan, Atmosphère

Jean-Luc Baray, V. Daniel, Gérard Ancellet, Bernard Legras. Planetary-scale tropopause folds in the southern subtropics. Geophysical Research Letters, 2000, 27 (3), pp.353-356. ⟨10.1029/1999GL010788⟩. ⟨insu-01411556⟩