Physical Oceanography

In the Northern Hemisphere, the north Indian Ocean exhibits unique oceanographic characteristics compared to those of its counterparts — the north Altantic and the north Pacific Oceans. Firstly, the northern Indian Ocean lies in the tropics — well below 30°N – and is land-locked on the northern side. Hence, there is no source of deep convection of the cold waters of polar origin. Secondly, the northern Indian Ocean experiences the semiannually reversing monsoon winds blowing from northeast during December-February and from southwest during June-September. The surface winds are consistent in their direction during these periods and are famously known as the Northeast monsoon and Southwest monsoon, respectively. There also exist inter-monsoon periods in between the monsoons, characterized by weak and variable winds, intense summer heating in May and mild heating during October. The sea bottom slopes up towards the north and merges with the continental shelf. The Indian Peninsula divides the north Indian Ocean into the Arabian Sea and Bay of Bengal. Though these marginal seas occupy the same latitudinal range, the water characteristics exhibit wide differences, which bring both the oceanographers and meteorologists to a common platform of understanding the monsoons, their response on these marginal seas in respect of climatic variability and living resources for the benefit of people. These marginal seas are forced by the above wind systems, solar heating owing to the lower latitudes, the immense evaporation, precipitation, particularly during the southwest monsoon period, and the huge river run-off, particularly in the Bay of Bengal. The circulation, especially in the equatorial region, differs markedly from the other two oceans. The Arabian Sea is connected to the warm, highly saline waters of the Persian Gulf and Red Sea.