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Titre du document / Document title

Triggering of the positive Indian Ocean dipole events by severe cyclones over the Bay of Bengal

Auteur(s) / Author(s)

FRANCIS P. A. (1) ; GADGIL Sulochana (1) ; VINAYACHANDRAN P. N. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Center for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore -12, INDE

Résumé / Abstract

In this paper, we suggest that positive Indian Ocean dipole events could be triggered by the occurrence of severe cyclones over the Bay of Bengal during April-May. All positive Indian Ocean dipole events during 1958-2003 are preceded by at least one such severe cyclone. Severe cyclones over the Bay of Bengal strengthen the meridional pressure gradient across the eastern equatorial Indian Ocean (EEIO) and hence lead to the intensification of the upwelling favourable southeasterlies along the Sumatra coast. Severe cyclones can also lead to a decrease in the integrated water vapour content and suppress convection over the EEIO. We suggest that the suppression of convection over the EEIO in turn, leads to the enhancement of convection over the western equatorial Indian Ocean (WEIO) and hence to the weakening of the westerlies along the central equatorial Indian Ocean (CEIO). This can lead to a positive feedback between suppression of convection over the EEIO and enhancement of the convergence and convection over the WEIO. If this positive feedback continues until the winds over the CEIO become easterlies, the convection over the EEIO remains suppressed for a period much longer than the synoptic scale. The strong upwelling caused by the easterlies along the equator and southeasterlies along the Sumatra coast decreases the sea surface temperature of the EEIO very rapidly and a positive dipole event gets triggered.

Revue / Journal Title

Tellus. Series A, Dynamic meteorology and oceanography    ISSN  0280-6495   CODEN TSAOD8 

Source / Source

Congrès
International reseach institute for climate and society (IRI). Workshop, Palisades.New-York , ETATS-UNIS (03/2006)
2007, vol. 59, no4, pp. 461-475 [15 page(s) (article)] (1 p.)

Langue / Language

Anglais

Editeur / Publisher

Blackwell, Oxford, ROYAUME-UNI  (1983) (Revue)

Mots-clés anglais / English Keywords

Indian Ocean

;

Severe weather

;

Indian ocean dipole

;

Space remote sensing

;

Bay of Bengal

;

Satellite observation

;

Observation data

;

time series analysis

;

Tropical cyclone

;

Triggering

;

Formation mechanism

;

Climatology

;

Mots-clés français / French Keywords

Océan Indien

;

Temps violent

;

Dipôle océan Indien

;

Télédétection spatiale

;

Golfe du Bengale

;

Observation par satellite

;

Donnée observation

;

Analyse série temporelle

;

Cyclone tropical

;

Déclenchement

;

Mécanisme formation

;

Climatologie

;

Mots-clés espagnols / Spanish Keywords

Océano Indico

;

Tiempo violento

;

Teledetección espacial

;

Golfo de Bengala

;

Observación por satélite

;

Dato observación

;

Ciclón tropical

;

Inducción

;

Mecanismo formacion

;

Climatología

;

Localisation / Location

INIST-CNRS, Cote INIST : 2121 A, 35400016140544.0060

Nº notice refdoc (ud4) : 18919360



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