11:35 AM - 11:50 AM
[ACG29-10] Interannual variability in sea surface height at southern mid-latitudes of the Indian
Ocean
Keywords:sea level variability, Rossby waves, interannual variability, south Indian Ocean, El Nino/Southern Oscillation
This study examines interannual variability in sea surface height (SSH) at southern
mid-latitudes of the Indian Ocean (10°-35°S). Our focus is on the relative role of local
wind forcing and remote forcing from the equatorial Pacific Ocean. We use satellite
altimetry measurements, an atmospheric reanalysis and a one-dimensional wave
model tuned to simulate observed SSH anomalies. The model solution is decomposed
into the part driven by local winds and that driven by SSH variability radiated from the
western coast of Australia. Results show that variability radiated from the Australian
coast is larger in amplitude than variability driven by local winds in the central and
eastern parts of the south Indian Ocean at mid latitudes (between 19° and 33°S),
whereas the influence from eastern boundary forcing is confined to the eastern basin
at lower latitudes (10° and 17°S). The relative importance of coastally forced variability
at mid latitudes is due to the weakness of wind stress curl anomalies in the south
Indian Ocean. Our analysis further suggests that SSH variability along the west coast
of Australia originates from remote wind forcing in the tropical Pacific, as is pointed out
by previous studies. The zonal gradient of SSH between the western and eastern parts
of the south Indian Ocean is also mostly controlled by variability radiated from the
Australian coast, indicating that interannual variability in meridional geostrophic
transport is driven principally by Pacific winds.
mid-latitudes of the Indian Ocean (10°-35°S). Our focus is on the relative role of local
wind forcing and remote forcing from the equatorial Pacific Ocean. We use satellite
altimetry measurements, an atmospheric reanalysis and a one-dimensional wave
model tuned to simulate observed SSH anomalies. The model solution is decomposed
into the part driven by local winds and that driven by SSH variability radiated from the
western coast of Australia. Results show that variability radiated from the Australian
coast is larger in amplitude than variability driven by local winds in the central and
eastern parts of the south Indian Ocean at mid latitudes (between 19° and 33°S),
whereas the influence from eastern boundary forcing is confined to the eastern basin
at lower latitudes (10° and 17°S). The relative importance of coastally forced variability
at mid latitudes is due to the weakness of wind stress curl anomalies in the south
Indian Ocean. Our analysis further suggests that SSH variability along the west coast
of Australia originates from remote wind forcing in the tropical Pacific, as is pointed out
by previous studies. The zonal gradient of SSH between the western and eastern parts
of the south Indian Ocean is also mostly controlled by variability radiated from the
Australian coast, indicating that interannual variability in meridional geostrophic
transport is driven principally by Pacific winds.