Implication of tropical lower stratospheric cooling in recent trends in tropical circulation and deep convective activity - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Atmospheric Chemistry and Physics Année : 2019

Implication of tropical lower stratospheric cooling in recent trends in tropical circulation and deep convective activity

Résumé

Large changes in tropical circulation from the mid-to-late 1990s to the present, in particular changes related to the summer monsoon and cooling of the sea surface in the equatorial eastern Pacific, are noted. The cause of such recent decadal variations in the tropics was studied using a meteorological reanalysis dataset. Cooling of the equatorial southeastern Pacific Ocean occurred in association with enhanced cross-equatorial southerlies that were associated with a strengthening of the deep ascending branch of the boreal summer Hadley circulation over the continental sector connected to stratospheric circulation. From boreal summer to winter, the anomalous convective activity center moves southward following the seasonal march to the equatorial In-dian Ocean-Maritime Continent region, which strengthens the surface easterlies over the equatorial central Pacific. Accordingly , ocean surface cooling extends over the equatorial central Pacific. We suggest that the fundamental cause of the recent decadal change in the tropical troposphere and the ocean is a poleward shift of convective activity that resulted from a strengthening of extreme deep convection penetrating into the tropical tropopause layer, particularly over the African and Asian continents and adjacent oceans. We conjecture that the increase in extreme deep convection is produced by a combination of land surface warming due to increased CO 2 and a reduction of static stability in the tropical tropopause layer due to tropical stratospheric cooling.
Fichier principal
Vignette du fichier
acp-19-2655-2019.pdf (7.84 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

hal-02172615 , version 1 (09-10-2020)

Licence

Paternité - Pas de modifications

Identifiants

Citer

Kunihiko Kodera, Nawo Eguchi, Rei Ueyama, Yuhji Kuroda, Chiaki Kobayashi, et al.. Implication of tropical lower stratospheric cooling in recent trends in tropical circulation and deep convective activity. Atmospheric Chemistry and Physics, 2019, 19 (4), pp.2655-2669. ⟨10.5194/acp-19-2655-2019⟩. ⟨hal-02172615⟩
154 Consultations
21 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More