Publications des scientifiques de l'IRD

Cretat J., Terray Pascal, Masson S., Sooraj K. P. (2018). Intrinsic precursors and timescale of the tropical Indian Ocean Dipole : insights from partially decoupled numerical experiment. Climate Dynamics, 51 (4), p. 1311-1332. ISSN 0930-7575.

Titre du document
Intrinsic precursors and timescale of the tropical Indian Ocean Dipole : insights from partially decoupled numerical experiment
Année de publication
2018
Type de document
Article référencé dans le Web of Science WOS:000439440200003
Auteurs
Cretat J., Terray Pascal, Masson S., Sooraj K. P.
Source
Climate Dynamics, 2018, 51 (4), p. 1311-1332 ISSN 0930-7575
The intrinsic precursors and timescale of the tropical Indian Ocean Dipole (IOD) are examined with the help of a partially coupled global experiment with decoupled SST over the tropical Pacific. The IOD does exist in the absence of sea surface temperature interannual variability in the tropical Pacific in our modeling framework, but has weaker amplitude and damped Bjerknes feedback. However, IOD variability is much more biennial in the absence than presence of El Nio Southern Oscillation, especially in the eastern equatorial Indian Ocean (IO). Such biennial rhythm results mainly from two mechanisms internal to the IO. The tropical ocean dynamics play a key role in the biennial anomalies during boreal winter with a sudden reversal of thermocline anomalies in the eastern equatorial IO forced by intraseasonal disturbances reminiscent of the Madden-Julian Oscillation (MJO). However, this preconditioning is not sufficient for triggering IOD events in the next boreal spring per se. The main trigger for pure IODs relates to tropical-extratropical interactions within the IO. Convection and diabating heating associated with negative IODs promote a Gill-type tropical response, excite mid-latitude wave-trains and subtropical blocking in the Southern Hemisphere that trigger positive subtropical IOD events during boreal winter. The latter promotes cold SST and anticyclonic circulation anomalies over the southeast IO that persist and migrate northeastward, triggering positive IOD events during the next boreal spring. Accounting for the complementary influence of tropical ocean dynamics coupled to MJO and tropical-extratropical ocean-atmosphere interactions may thus help improving IOD predictability.
Plan de classement
Limnologie physique / Océanographie physique [032]
Description Géographique
OCEAN INDIEN ; ZONE TROPICALE
Localisation
Fonds IRD [F B010073687]
Identifiant IRD
fdi:010073687
Contact