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A Subsurface Indian Ocean Dipole Response to Tropical Volcanic Eruptions
Author(s) -
Izumo Takeshi,
Khodri Myriam,
Lengaigne Matthieu,
Suresh Iyyappan
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl078515
Subject(s) - westerlies , volcanism , volcano , geology , climatology , atmospheric sciences , environmental science , tectonics , geochemistry , seismology
The impacts of explosive volcanism on the densely populated Indian Ocean (IO) region remain elusive. Dedicated sensitivity experiments indicate that tropical volcanic eruptions induce a stronger surface cooling over Africa than of ocean, promoting westerlies in the equatorial IO. These westerlies drive a subsurface response reminiscent to that of a negative IO Dipole (IOD) during autumn in the year of eruption. The eruption also drives an enhanced cooling over the northwestern IO as a direct response to climatological cloud cover distribution. The resulting anomalous zonal sea surface temperature gradient contributes to enhance equatorial westerly anomalies in summer. The response is sensitive to the IO preconditioning, being larger when the system is favorable to a positive IOD development. Volcanic eruptions also induce a subsurface IOD‐like response in the multimodel database from the Coupled Model Intercomparison Project Phase 5 as well as a primary productivity decrease in the eastern IO.