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OCEANMRAPHTC ASSESSMENT tr TIf EAST ASIAN 5EA5
Aprilani SocAiarto
National Institute of Oceanology
Jakarta, Indonesia
ABSTRACT
This paper reviews oceanographic conditions in South-East Asian waters, in
particular highlighting the monsoonal influence on oceanographic features. It gives
a general assessrnent of atmospheric and water circulation and tidal patterns, and
summarizes the data rt ihe discontinuity layer, temperature, salinity, dissolved
oxygen' and transpareney of the waters in the region. Finally it describes the
present knowledge of nutrients and pnimary productivity, and associated
phenomena such as upwelling.
Introduction
The East Asian Seas actually cover I very large area in the western Pacific Ocean,
bordered by the Bering Ses to the North, the lndian Ocean to the south, the coasts of
continental Asia to the West and the Pacific Ocean to the East. However, the East Asian
Seas Action Plan of the United Nations Environment Proqramme (UNEP) is limited to the
Souih-East Asian Region, and this oceanographic assessment concentrales on that region. This
assessrnenl is largely based on the work of Wyrtki (f96f) and various existing reviews such as
Soegiarto and Birowo (1975), Soegiarto (1978) and Soegiarto (1901).
The South-East Asian Waters
The waters and islands between Asia and Australia and between the Pacific and the
Indian oceans form a geognaphical unit because of thein special structure and position. In
geographical lerms, the whole region is a part of Asia and is referred to as Soulh-East Asia,
In oceanographic terms, the waters of ihe region are part of the Pacific Ocean, which is
separated from the Indian Ocean by the islands of Sumatra, Java, and the Nusa Tenggara
(Lesser Sunda). The seas in lhe region draw lheir water from the Pacific, to which lhey
provide access.
The South-East Asian waters comprise the Andaman Sea, the Straits of Mallaca, the
Straits of Singapore, the South China Sea, the Java Sea, the Flores Sea, the Banda Sea, the
Arefura Sea, the Timor Sea, the Celebes Sea, the Sulu Sea, and the Philippine Sea (Figure lI
Tlp whole body of water covers 8.94 million sguare kilometres in area, which represents
about 2.5 per cenl of the world's ocean surface.
The South-East Asian seas form me geographic unit distinct from the Pacific and
Indian means. Tle Andaman Sea is part of the Indian Ocean but should be regarded as
South-Emt Asian waters. It is perhaps rather zurprising thet the Timor and Arafura Seas and
Gulf of Carpentaria are often regarded, in oceanographic terms, as part of the pacific
Ocean.
Nearly all types of topographical features are found in South-East Asian waters, such
as shallow continental shelves, deep sea beins, troughs, trenches, continental slopes, and
volcanic and coral islands. In its distrihrtion of water and land the South-East Asian region is
one of ihe most complex structures on earth. The nurneroue large and small islands divide the
waters into different seas connected by many channels, passeges, and straits. The complexity