Future challenges in shelf seas - Introduction to the Physical and Biological Oceanography of Shelf Seas - page 360

Pacific water

Chukchi
Sea

East Siberian
Sea

Laptev
Sea

Kara
Sea

Atlantic water

Barents
Sea

Vertical mixing

Lateral exchange

Figure 11.4 Arctic Ocean exchange with the North Atlantic, and the transformation of water
masses. Figure courtesy of Yueng-Djern Lenn, Bangor University, UK.

tropical margins of the African and American continents, though in south-east Asia
and to the north of Australia there are large areas of broad shelf comparable in
extent to the major mid-latitude shelf seas.
As we noted in Chapter 2 ( Section 2.3.2 ), many of these areas are subject
to strong seasonal freshwater runoff which dominates over heat exchange in
terms of buoyancy input, driven by monsoons, promoting a seasonal cycle which is
somewhat analogous to that of the heating-cooling cycle in mid latitudes. They also
differ from mid-latitude shelf seas in that, being close to the equator, the Coriolis
parameter is close to zero so the influence of rotation is greatly diminished.
To date, these areas have been little studied so that understanding of their physical
and biological systems is limited, in spite of their considerable economic importance
to the large populations living in the coastal areas bordering these seas. As an
example of a tropical ROFI system, consider the Gulf of Thailand, shown in
Fig. 11.5 . This is a large shelf sea with an average depth of

50 metres and an area

∼

10 5 km 2 ) comparable to that of the North Sea. The Gulf has a relatively
energetic tidal regime which will drive considerable tidal mixing, as can be seen from
the plot of the SH parameter in Fig. 11.5a . Large freshwater inputs to the Gulf occur
during the wet season (June to October) from rivers flowing directly into the Gulf and

(2.7