A gap in the Indo‐Pacific warm pool over the South China Sea in boreal winter: Seasonal development and interannual variability

Liu, Qinyu; Jiang, Xia; Xie, Shang‐Ping; Liu, W. Timothy

doi:10.1029/2003jc002179

Cited by 170 publications

(159 citation statements)

References 30 publications

(48 reference statements)

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“…h , implying the divergence and convergence of eddy energy, exist along the eastern and western side of the southwestward horizontal current which may be caused by advection [Liu et al, 2004]. Compared with the abovementioned terms, tendency of EKE is small (Figure 4e), while the turbulent processes acts as the main sinks of the eddy energy with high values at southwestern SCS and the Luzon Strait (Figure 4f).…”

Section: Eddy Energy Sources and Sinksmentioning

confidence: 96%

Eddy energy sources and sinks in the South China Sea

Yang

Liu

et al. 2013

JGR Oceans

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[1] The eddy energy sources and sinks in the South China Sea (SCS) are studied based on a high-resolution ocean circulation model. Eddies are found to acquire their energy from barotropic instability (BT), the release of available potential energy (APE) associated with baroclinic instability (BC) and horizontal convergence from surrounding areas, while they lose energy due to turbulent processes. Both the eddy energy sources and sinks show western intensification with their maximum around the southwestern SCS where most of the wind-input energy occurs, and the Luzon Strait where the Kuroshio intrudes the SCS in winter. Unlike that in the open ocean, the eddy energy in the inner SCS is confined to the upper layer. Besides, the eddy energy indicates clear seasonal variability, especially at the Luzon Strait where the eddy activity is much stronger in winter than in summer. Energy budget analysis suggests that APE releasing is found to be the most important eddy energy source, accounting for over 60% of the total, followed by energy convergence from surrounding areas in horizontal direction (around 20%) and energy released from BT (around 15%). Most of the generated energy is mainly balanced by the turbulent processes, while both of the downward energy flux and tendency term are negligible.

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Section: Eddy Energy Sources and Sinksmentioning

confidence: 96%

Eddy energy sources and sinks in the South China Sea

Yang

Liu

et al. 2013

JGR Oceans

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“…The impact of topography on the SCS summer climate characteristics was further validated by a model [86]. There exists a summer cold tongue in the temperature structure associated with the SCSWBC; in addition, there is still a significant cold tongue in the same region in winter, and the generation of the winter cold tongue is related to the southward cold advection by the SCSWBC [87]. Xie et al [88] found that the 30-60 day intraseasonal oscillation of SST associated with the SCSWBC was under the influence of the Vietnam coastal upwelling [67,68], and this intraseasonal oscillation amplitude was obviously more significant near Vietnam coast than in any other regions.…”

Section: Air-sea Interactionmentioning

confidence: 99%

Progress of regional oceanography study associated with western boundary current in the South China Sea

et al. 2013

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Recent progress of physical oceanography in the South China Sea (SCS) associated with the western boundary current (WBC) and eddies is reviewed in this paper. It includes Argo observations of the WBC, eddy detection in the WBC based on satellite images, cross-continental shelf exchange in the WBC, eddy-current interaction, interannual variability of the WBC, air-sea interaction, the SCS throughflow (SCSTF), among others. The WBC in the SCS is strong, and its structure, variability and dynamic processes on seasonal and interannual time scales are yet to be fully understood. In this paper, we summarize progresses on the variability of the WBC, eddy-current interaction, air-sea interaction, and the SCSTF achieved in the past few years. Firstly, using the drifting buoy observations, we point out that the WBC becomes stronger and narrower after it reaches the central Vietnam coast. The possible mechanisms influencing the ocean circulation in the northern SCS are discussed, and the dynamic mechanisms that induce the countercurrent in the region of northern branch of WBC in winter are also studied quantitatively using momentum balance. The geostropic component of the WBC was diagnosed using the ship observation along 18°N, and we found that the WBC changed significantly on interannual time scale. Secondly, using the ship observations, two anti-cyclonic eddies in the winter of 2003/2004 in the northern SCS, and three anti-cyclonic eddies in the summer of 2007 along 18°N were studied. The results show that the two anti-cyclonic eddies can propagate southwestward along the continental shelf at the speed of first Rossby wave (~0.1 m s 1 ) in winter, and the interaction between the three anti-cyclonic eddies in summer and the WBC in the SCS is preliminarily revealed. Eddies on the continental shelf of northern SCS propagated southeastward with a maximum speed of 0.09 m s 1 , and those to the east of Vietnam coast had the largest kinetic energy, both of which imply strong interaction between eddy activity and WBC in the SCS. Thirdly, strong intraseasonal variability (ISV) of sea surface temperature (SST) near the WBC regions was found, and the ISV signal of SST in winter weakens the ISV signal of latent heat flux by 20%. Fourthly, the long-term change of SCSTF volume transport and its connection with the ocean circulation in the Pacific were discussed.South China Sea, western boundary current, eddy, eddy-current interaction, intraseasonal variability, South China Sea thoughflow Citation:Wang D X, Liu Q Y, Xie Q, et al. Progress of regional oceanography study associated with western boundary current in

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“…It is well-known that the cold tongue is caused by the winter monsoon, both directly through enhanced upward heat fluxes from strong surface wind and indirectly through cold water advection due to the western boundary current off the coast of Vietnam (Liu et al, 2004) set up by the monsoon. But, does the cold tongue have any impact on the winter monsoon itself and the associated rainfall in the Maritime Continent?…”

Section: Introductionmentioning

confidence: 99%

“…Centurioni et al (2009) estimated that the significant strength of Ekman currents off Vietnam is associated with the wind stress curl in the winter monsoon season. Liu et al (2004) showed that the western boundary current (e.g. Stommel, 1948) along the Vietnam coast transports colder seawater southward and forms the so-called cold tongue, an extension of cool sea surface temperature (SST) in SCS, which at the coldest is about 298 K. The cold tongue starts to form in November and lasts until March (Chen et al, 2003) before disappearing in April.…”

Section: Introductionmentioning

confidence: 99%

Effects of the cold tongue in the South China Sea on the monsoon, diurnal cycle and rainfall in the Maritime Continent

Koseki

Koh

Teo

2012

Quart J Royal Meteoro Soc

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We investigate the effects of the cold tongue in the South China Sea (SCS) on the winter monsoon, rainfall and diurnal cycle in the maritime continent using a numerical model verified with satellite rainfall and reanalysis data. Composite analysis of the observation and reanalysis data based on cold tongue index indicates that the penetration of the monsoon to Java Sea is enhanced when the cold tongue is strong. A sensitivity experiment without the cold tongue shows that the winter monsoon is diminished over SCS and around coastal regions because of anomalous low-level cyclonic circulation associated with enhanced convection over SCS due to the warmer sea surface temperature (SST). The diurnal cycle, in particular the night-morning rainfall, over the sea in coastal regions is modified. The effect on daytime rainfall over the land is relatively weaker. Along the northern coast of Java far from the SCS, the night-morning rainfall is much reduced over the Java Sea when the cold tongue is suppressed because of the weakened land-breeze front as a result of the weakened northerly monsoon. In contrast, the afternoon-evening rainfall on Java Island is slightly enhanced, showing that the local impacts are not simply the result of large-scale subsidence from the convective anomaly in the SCS. Along the northwestern coast of Borneo adjacent to the SCS, the weakened winter monsoon tends to reduce the rainfall at the land-breeze front near the coastline. On the other hand, the warmer SST forces a stronger land breeze and the weakened monsoon encourages further and faster offshore propagation of the land-breeze front. Consequently, the rainfall peak shifts further offshore in the sensitivity experiment. We conclude that the cold tongue has two effects, the sustenance of a strong monsoon (indirect effect) and the cooling of local SST (direct effect), which have opposite influences on the diurnal cycle in the Maritime Continent.

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A gap in the Indo‐Pacific warm pool over the South China Sea in boreal winter: Seasonal development and interannual variability

Cited by 170 publications

References 30 publications

Eddy energy sources and sinks in the South China Sea

Eddy energy sources and sinks in the South China Sea

Progress of regional oceanography study associated with western boundary current in the South China Sea

Effects of the cold tongue in the South China Sea on the monsoon, diurnal cycle and rainfall in the Maritime Continent

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