Fronts Of The Southeast Indian Ocean And Their Variations

Baroclinic component is the dominant part of Antarctic Circumpolar Current (ACC), and baroclinic transportation associated with fronts makes up the majority part of the total baroclinic transportation of ACC. Therefore it is critical to study the properties and variations of oceanic fronts for understanding ACC. Because of the enormous area of the Southern Ocean and rough in situ condition, the knowledge about the oceanic fronts there is still limited. Although many scientists have investigated the fronts in the Southern Indian Ocean, most of the studies were based on thermohaline properties of the fronts. Most of measurements were implemented in austral summer with sparse spatial resolution and distributed along cruise tracks of Antarctic replenishment vessels. Comprehensive and continuous measurements are rare. Especially the knowledge about South Indian Ocean is less than other parts of Southern Ocean. The in situ observations of Chinese National Antarctic Research Expeditions in Southern Ocean were focused on the southeast Indian Ocean mostly, therefore the oceanic fronts in the southeast Indian Ocean between 70°and 150°E are chosen as the objectives of the present study.Most of the oceanic fronts in the southeast Indian Ocean is accompanied with strong baroclinic geostrophic currents. Different from previous view in studying fronts, strong currents related to fronts to study and identify fronts, through which the current characteristics within fronts are shown. Based on these results, the locations, velocity, width and possible variations of fronts in the section along 115°E is described. The variations of fronts in the southeast Indian Ocean are analyzed in eddy kinetic energy and thermohaline properties, and the frontogenesis of oceanic fronts is also discussed preliminarily. Main results are as follows:1. The locations and orientations of the Subantarctic Front (SAF), the primary Polar Front and Southern ACC Front (SACCF) in the ACC of the Southeast Indian Ocean can be identified more precisely by the current distribution derived from ADCP data than by hydrographic data, because these fronts are usually accompanied by strong currents, although the speed coinciding with the SACCF is less than that of the SAF and primary PF. The secondary PF does not always coincide with a jet. The location and orientation of the STF is more difficult to be identified through current data, since there usually is no jet accompany it. The activities of eddies could strengthen and split the current within the SAF.2. On average the principal axis of ACC is consist of two flows in the section along 115°E...