Open AccessDynamics of 2015 positive Indian Ocean Dipole
Author(s) -
Putri Adia Utari,
Mokhamad Yusup Nur Khakim,
Dedi Setiabudidaya,
Iskhaq Iskandar
Publication year - 2019
Publication title -
journal of southern hemisphere earth systems science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 7
ISSN - 2206-5865
DOI - 10.1071/es19002
Subject(s) - climatology , sea surface temperature , indian ocean dipole , ocean heat content , monsoon , mixed layer , latent heat , walker circulation , subtropical indian ocean dipole , geology , indian ocean , oceanography , environmental science , atmospheric sciences , geography , meteorology
Evolution of typical positive Indian Ocean Dipole (pIOD) event was dominated by a significant sea-surface temperature (SST) cooling in the south-eastern tropical Indian Ocean. Interestingly, during the evolution of 2015 pIOD event, the SST in the south-eastern tropical Indian Ocean did not reveal significant cooling, instead anomalous strong SST warming took place in the western tropical Indian Ocean off the East African coast. This anomalous SST warming was associated with a weakening of the Asian summer monsoon. Furthermore, analysis on the mixed layer heat budget demonstrated that the evolution of the 2015 pIOD event could be attributed mainly to the air-sea heat flux. By decomposing the air-sea heat flux, it is found that reduced latent heat loss plays an important role on the SST warming in the western pole and keeping SST warm in the eastern pole. We note that a residual term also may play a role during the initial development of the event. In contrast to the SST pattern, the subsurface temperature revealed a clear positive dipole pattern. Shallow (deep) 20°C isothermal layer in the eastern (western) equatorial Indian Ocean was observed during boreal summer. This robust subsurface dipole pattern indicated that the subsurface ocean response was largely wind driven through the equatorial wave dynamics as previously suggested.