Publication Date:
2017-04-04
Description:
The interannual variability in the tropical
Indian Ocean, and in particular the Indian Ocean di-
pole mode (IODM), is investigated using both obser-
vations and a multi-decadal simulations performed by
the coupled atmosphere–ocean general circulation
model SINTEX. Overall, the characteristics of the
simulated IODM are close to the features of the ob-
served mode. Evidence of significant correlations be-
tween sea level pressure anomalies in the southeastern
Indian Ocean and sea surface temperature anomalies in
the tropical Indian and Pacific Oceans have been found
both in observations and a multi-decadal simulation. In
particular, a positive SLP anomaly in the southeastern
part of the basin seems to produce favorable conditions
for the development of an IODM event. The role
played by the ocean dynamics both in the developing
and closing phases of the IODM events is also inves-
tigated. Our results suggest that, during the developing
phase, the heat content and SST variability associated
with the IODM are influenced by a local response of
the ocean to the winds, and a remote response with the
excitation of Kelvin and Rossby waves. Ocean wave
dynamics appear to be important also during the dying
phase of the IODM, when equatorial downwelling
Kelvin waves transport positive heat content anomalies
from the western to the eastern part of the basin,
suppressing the zonal heat content anomaly gradient.
The results obtained from the model suggest a mechanism for the IODM. This mechanism is generally
consistent with the characteristics of the observed
IODM. Furthermore, it might give some clue in understanding the correlation between IODM and ENSOactivity found both in the model and in the observations.
Description:
This work has been supported by the European Community contract SINTEX ENV4-CT98-0714.
Description:
Published
Description:
567-582
Description:
4A. Clima e Oceani
Description:
JCR Journal
Description:
restricted
Keywords:
Coupled General Circulation Model
;
Indian Ocean Dipole Mode
;
Interannual variability
;
03. Hydrosphere::03.03. Physical::03.03.03. Interannual-to-decadal ocean variability
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Permalink
