• Basil Mathew

      Articles written in Journal of Earth System Science

    • Hydrography and circulation off the Antarctica in the Indian Ocean region

      G S Sharma Basil Mathew

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      The hydrography and circulation pattern off Antarctica in the Indian Ocean region are studied using vertical sections of temperature, salinity and oxyty approximately along 20°E, 77°E and 90°E, and the dynamic topography of the sea surface with reference to 1000 db. Based on the oceanographic characteristics, the whole region under study can be divided into three zones, the extreme ends being characterised by the frontal structure. The dicothermal layer is conspicuous during summer south of 50°S. The surface flow around Antarctica is mainly zonal. The East Wind Drift, found as a narrow westward flow near Antarctica, is observed at a lower latitude in the eastern Indian Ocean where the land extends northword. Contrary to expectation there is evidence of a westward flowing surface current at about 35°S between 45°E and 65°E.

    • On the observed synoptic variability in the thermal structure of the upper northern Bay of Bengal during MONEX-79

      R R Rao Basil Mathew

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      The short-term variability observed in the near surface meteorological parameters and in the vertical thermal structure of the upper layers of the northern Bay of Bengal during a weak monsoonal regime is examined with the aid of time series measurements. The variability of the mixed layer depth is interpreted in terms of forced mixing caused by the surface wind stress and free mixing by buoyancy flux, Ekman pumping controlled by the curl of the surface wind stress, convergence associated with a clockwise gyral circulation and stratification caused by freshwater discharges from rivers. The daily-averaged current vectors in the upper layers indicate the presence of clockwise gyral circulation in the polygon area.

    • Water characteristics and transport of the Antarctic circumpolar current in the Indian Ocean

      P M Muraleedharan Basil Mathew

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      Geostrophic velocities are computed across meridians 37 °E and 105 °E using hydrographic data. The estimated mass transport is represented on a temperature-salinity diagram. The characteristics of the water within the Antarctic circumpolar current at 37 °E and 105 °E are discussed. The computed transport agrees with the previous estimates. Transports due to the current between 45 °S and the Antarctic continent at these two meridians are comparable. The westerly flow south of 42 °S at 105 °E is associated with a cyclonic eddy which appears to be a permanent feature, whereas the one at 50 °S is related to the topography of the region.

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