Ocean Currents, Bathymetry & Marine Ecology
Ocean circulation is driven by wind stress, Earth's rotation (Coriolis effect), and density gradients arising from temperature and salinity variations, known as thermohaline circulation or the global ocean conveyor belt. In the North Indian Ocean, monsoon wind reversals uniquely invert surface current directions between the Southwest and Northeast monsoons, influencing upwelling systems along the Malabar and Somali coasts. Oceanographic phenomena such as the Indian Ocean Dipole (IOD) and El Niño-Southern Oscillation (ENSO) exert profound teleconnections on South Asian weather and marine productivity. The preservation of sensitive marine ecosystems—including the coral reefs of Lakshadweep, Andaman and Nicobar Islands, and Gulf of Mannar—is vital for benthic biodiversity and coastal climate buffering.
Key Concepts & Examination Highlights
- The Indian Ocean is the only ocean where surface currents completely reverse direction seasonally due to monsoon winds.
- The Coriolis force deflects ocean currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
- Thermohaline circulation is governed by water density variations determined by ocean temperature and salinity.
- The Gulf of Mannar Marine National Park was India's first marine biosphere reserve established in 1989.