Chemical Oceanography

Like most other oceanographic characteristics, chemical features of the Indian Ocean, particularly of its northern part, also distinguish it from the other oceans due to its unusual geographical setting. In the north, the Asian landmass bounds the Indian Ocean at rather low latitudes and isolates it from the deep convection areas of the northern hemisphere. 1 Also, unlike the Pacific and the Atlantic Oceans, the Indian Ocean does not have a continuous eastern land boundary as it is connected to the Pacific through the Indonesian waters. Thus, a typical eastern boundary circulation is absent here. 2 In the absence of a connection between the cold climatic regions of the two hemispheres, the subsurface renewal in the Indian Ocean mostly occurs through advection of waters [Subantarctic Mode Water (SMW), Antarctic Intermediate Water (AAIW), and the deep and bottom waters of the North Atlantic and Antarctic origins] from the circumpolar region in the south and, to a smaller extent, from the east (Pacific throughflow). However, there are some local sources of subsurface (intermediate) waters in the northwestern region itself — the Persian Gulf and the Red Sea. While the outflows from these marginal seas do bring about some renewal, they actually accentuate the isolation of intermediate layers of the northern Indian Ocean by preventing the flow of intermediate waters from the south. 2 Thus, differences in morphology and associated climate from the other two oceans give rise to unique circulation, biogeochemical cycling and, a resulting distribution of chemical constituents in the Indian Ocean.