ITF in a coupled GCM and its interannual variability related to ENSO and IOD

摘要

The interannual variability of the mass transport of the Indonesian Throughflow (ITF) is very possible to be connected with the El Ni(n)o-Southern Oscillation (ENSO) in the Pacific Ocean and/or the Indian Ocean Dipole (IOD). The IPSL (Institute Pierre-Simon Laplace) coupled general circulation model (CGCM) was employed to examine the interannual variability of the ITF and understand its relationship with the climatic variation in both the basins. A 1 000 a integration was conducted and an annual mean model output was utilized. The pathways of the simulated ITF are reasonable within the Indonesian seas. The major transport occurs in the upper 300 m,with an annual mean transport of 15.68×106 m3/s, among which the 13.83×106 m3/s through the Makassar Strait is the principal component. The interannual variability of the ITF transport is significant in a 2～4 a period. The relationship between sea level differences across the Indonesian seas (sites in the western Pacific north of the equator and south coast of Java, respectively) and the ITF transport is straightforward on the interannual time-scale with a simultaneous correlation of 0.82. Further investigation indicates that the preceding climatic variation in the tropical Pacific is related to the ITF transport anomaly. The ENSO-like pattern leads the extreme of ITF transport by 1 a, with the correlation between a Ni(n)o 3 SST index and the ITF transport of 0.37. It means that there tends to be an El Ni(n)o anomaly in the Pacific 1 a before a large ITF transport. The simultaneous correlation between the Ni(n)o 3 SST index and the ITF transport is -0.34. The patterns of sea surface temperature and sea surface height are, however, not the typical ENSO anomaly. The ITF transport is more related to the concurrent interannual variability over the Indian Ocean. The simultaneous correlation between the ITF transport and the dipole mode index is 0.46 and the pattern of upper layer anomaly is much like that of the IOD.