Spatial and Temporal Variability of Sea Surface Height in the Southeastern Tropical Indian Ocean Based on the Satellite Altimeter Data
Abstract: Sea surface height
(SSH) data from merged-satellite observations (e.g. TOPEX/Poseidon, JASON and
ERS) were used to evaluate the spatial and temporal variations of sea surface
circulations in the southeastern tropical Indian Ocean (SETIO). A Complex
Empirical Orthogonal Function (CEOF) was used to extract the dominant mode of variability
in the SETIO region. The results show that the first mode accounts for 41.2% of
the total variance dominates the variation. The second mode accounts for 18.2%
of the total variance, while the third and the fourth modes explain 6.5% and
2.6% of the total variance, respectively. The spectrum analysis indicates that
the 35-day variations is a prominent feature in all CEOF modes. Furthermore,
semiannual variation at period of about 180-day was observed in the first third
modes, while the annual variation of about 300-day was only observed in the
first two modes. A relatively strong variation at period of around 500-day was
observed in the first, second and fourth modes. It is suggested that the
spatial and phase pattern of the first and third modes are related to the
propagation of the Kelvin waves generated by wind stress over the equatorial
Indian Ocean. On the other hand, the second was likely related to the local
upwelling and downwelling generated by the seasonal changes in the alongshore winds.
Furthermore, the fourth mode represents the oceanic eddy generated from the
downstream straits of the Indonesian Throughflow.
Author: Iskhaq Iskandar,
Wijaya Mardiasnyah and Dedi Setiabudidaya
Journal Code: jpmatematikagg140004
