418
Chapter 11: The Pacific Ocean
China Sea. The resultant sediment regime in shoal water is a paradigm for domination
by mobile, thixotropic mud banks: similar processes along western India or the Guiana
coast of South America are weak in comparison. Sedimentary loads may be as much as
20 kg m
−3 at the mouths of the Yellow River at flood tide and, when transport slows
down, this material sinks out and leads to the development of offshore mud banks that
continually shift by tidal resuspension and transport (Wang, 1983). These mud banks
form lunate features that lie normal to the coast and extend up to 75 km offshore; a
feature termed the Great Sandbank formed in this way occupies much of the western
part of the Yellow Sea. Further, recall that in 2009 the Three Gorges dam on the Yangtse
should be completed, and that these works are expected to have major consequences for
the ecology of the entire shelf region of eastern China: already, concerns are expressed
for the potential loss of fishery resources.
Tidal fronts have been studied in three areas: in the Yellow Sea, on the western coast of
Korea, and on the central part of the Chinese coast. Nearly vertical isotherms follow the
familiar pattern in tidal mixing fronts that loop around groups of islands off SW Korea;
the area of low stability within the loop is marked by cold water of high salinity (Lie, 1989).
Defining Characteristics of Regional Oceanography
The East China and Yellow (Huanghai) Seas are large epicontinental shelf-depth seas,
whereas the shelf of the eastern Sea of Japan is very narrow. The East China Sea is open
to the Pacific Ocean except for the presence of Taiwan and the chain of Ryuku Islands,
whereas the Yellow Sea is enclosed on three sides by the Asian continent. The Bohai Sea is
a smaller, very shallow (<20 m) basin at the head of the Yellow Sea. Nontidal circulation
in these epicontinental seas is forced by the strongly seasonal regional wind system, and
the invariant presence at the shelf edge of warm Kuroshio flow.
Southward from the Yellow Sea the wind regime is dominated by the seasonally reversing
Asian monsoon: the Northeast Monsoon in winter and the Southwest in summer. Like New
England and Atlantic Canada, in the northern part of this province there is an extreme
contrast between winter and summer conditions. The cold, dry northerly winds strongly cool
the surface water in winter; cooling is reversed with the advance of the southerly monsoon
that begins in early May and by mid-July has reached the northern Yellow Sea so that the
entire province lies under the influence of a southerly flow of tropical air (Barry and Chorley,
1982); this regime induces a seasonal temperature range of about 10
C between winter and
summer, even at Hong Kong near the southern end of the province.
The thermocline is deepened in winter from 30–50 m to about 100 m at the shelf edge,
but in the East China Sea intersects the bottom at only 20 km of the coast (Watts, 1972;
Chan, 1970). Farther north, in the Yellow Sea, outbreaks of cold air from the Siberian
High, accompanied by strong winds, force almost complete mixing in both Bohai and
Yellow Seas. Thus, a very cold surface water mass develops there during winter, reaching
0
C in the inner Bohai Sea, where stratification is quite broken down. Subsequently,
summer warming reaches 28
C in the central Yellow Sea but a cold bottom-water mass
of 4–5
C lies below a remarkably steep thermocline (Wang and Zhu, 1991). The summer
temperature of the cold subthermocline water mass is related to regional air temperatures
of the previous winter.
Flow of modified coastal water from the western side of the Yellow Sea forms the
southward China Coastal Current of winter that, under the influence of the Siberian
northerly winds, passes through the Taiwan Strait (Shaw, 1992). This southward flow is
reinforced by discharge of freshwater from the Yellow and Yangtse Rivers and is associated
with a persistent cyclonic eddy, 100–200 km across, located south of Cheju Island; this
eddy is well predicted by geostrophic calculations and has cool, high-salinity water at its
center (Mao et al., 1986). During summer, flow in the China Coastal Current is reversed
Chapter 11: The Pacific Ocean
China Sea. The resultant sediment regime in shoal water is a paradigm for domination
by mobile, thixotropic mud banks: similar processes along western India or the Guiana
coast of South America are weak in comparison. Sedimentary loads may be as much as
20 kg m
−3 at the mouths of the Yellow River at flood tide and, when transport slows
down, this material sinks out and leads to the development of offshore mud banks that
continually shift by tidal resuspension and transport (Wang, 1983). These mud banks
form lunate features that lie normal to the coast and extend up to 75 km offshore; a
feature termed the Great Sandbank formed in this way occupies much of the western
part of the Yellow Sea. Further, recall that in 2009 the Three Gorges dam on the Yangtse
should be completed, and that these works are expected to have major consequences for
the ecology of the entire shelf region of eastern China: already, concerns are expressed
for the potential loss of fishery resources.
Tidal fronts have been studied in three areas: in the Yellow Sea, on the western coast of
Korea, and on the central part of the Chinese coast. Nearly vertical isotherms follow the
familiar pattern in tidal mixing fronts that loop around groups of islands off SW Korea;
the area of low stability within the loop is marked by cold water of high salinity (Lie, 1989).
Defining Characteristics of Regional Oceanography
The East China and Yellow (Huanghai) Seas are large epicontinental shelf-depth seas,
whereas the shelf of the eastern Sea of Japan is very narrow. The East China Sea is open
to the Pacific Ocean except for the presence of Taiwan and the chain of Ryuku Islands,
whereas the Yellow Sea is enclosed on three sides by the Asian continent. The Bohai Sea is
a smaller, very shallow (<20 m) basin at the head of the Yellow Sea. Nontidal circulation
in these epicontinental seas is forced by the strongly seasonal regional wind system, and
the invariant presence at the shelf edge of warm Kuroshio flow.
Southward from the Yellow Sea the wind regime is dominated by the seasonally reversing
Asian monsoon: the Northeast Monsoon in winter and the Southwest in summer. Like New
England and Atlantic Canada, in the northern part of this province there is an extreme
contrast between winter and summer conditions. The cold, dry northerly winds strongly cool
the surface water in winter; cooling is reversed with the advance of the southerly monsoon
that begins in early May and by mid-July has reached the northern Yellow Sea so that the
entire province lies under the influence of a southerly flow of tropical air (Barry and Chorley,
1982); this regime induces a seasonal temperature range of about 10
C between winter and
summer, even at Hong Kong near the southern end of the province.
The thermocline is deepened in winter from 30–50 m to about 100 m at the shelf edge,
but in the East China Sea intersects the bottom at only 20 km of the coast (Watts, 1972;
Chan, 1970). Farther north, in the Yellow Sea, outbreaks of cold air from the Siberian
High, accompanied by strong winds, force almost complete mixing in both Bohai and
Yellow Seas. Thus, a very cold surface water mass develops there during winter, reaching
0
C in the inner Bohai Sea, where stratification is quite broken down. Subsequently,
summer warming reaches 28
C in the central Yellow Sea but a cold bottom-water mass
of 4–5
C lies below a remarkably steep thermocline (Wang and Zhu, 1991). The summer
temperature of the cold subthermocline water mass is related to regional air temperatures
of the previous winter.
Flow of modified coastal water from the western side of the Yellow Sea forms the
southward China Coastal Current of winter that, under the influence of the Siberian
northerly winds, passes through the Taiwan Strait (Shaw, 1992). This southward flow is
reinforced by discharge of freshwater from the Yellow and Yangtse Rivers and is associated
with a persistent cyclonic eddy, 100–200 km across, located south of Cheju Island; this
eddy is well predicted by geostrophic calculations and has cool, high-salinity water at its
center (Mao et al., 1986). During summer, flow in the China Coastal Current is reversed