Observed subsurface eddies near the Vietnam coast of the South China Sea

In this study, subsurface eddies near the Vietnam coast of the South China Sea were observed with in situ observations, including Argo, CTD, XBT and some processed and quality controlled data. Based on temperature profiles from four Argo floats near the coast of Vietnam, a subsurface warm eddy was identified in spring and summer. The multi-year Argo and Global Temperature and Salinity Profile Programme(GTSPP) data were merged on a seasonal basis based on the data interpolating variational analysis(DIVA) method to reconstruct the three-dimensional temperature structure. There is a warm eddy in the central subsurface at 12.5°N, 111°E below300 m depth in spring, which does not exist in autumn and is weak in winter and summer. From CSIRO Atlas of Regional Seas(CARS) and Generalized Digital Environment Model(GDEM) reanalysis data, this subsurface warm eddy is also verified in spring.

Influence of two inlets of the Luzon overflow on the deep circulation in the northern South China Sea

An inverse reduced-gravity model is used to simulate the deep South China Sea(SCS)circulation.A set of experiments are conducted using this model to study the influence of the Luzon overflow through the two inlets on the deep circulation in the northern SCS.Model results suggest that the relative contribution of these inlets largely depends on the magnitude of the input transport of the overflow,but the northern inlet is more efficient than the southern inlet in driving the deep circulation in the northern SCS.When all of the Luzon overflow occurs through the northern inlet the deep circulation in the northern SCS is enhanced.Conversely,when all of the Luzon overflow occurs through the southern inlet the circulation in the northern SCS is weakened.A Lagrangian trajectory model is also developed and applied to these cases.The Lagrangian results indicate that the location of the Luzon overflow likely has impacts upon the sediment transport into the northern SCS.

Change of Tropical Cyclone Heat Potential in Response to Global Warming

Tropical cyclone heat potential （TCHP） in the ocean can affect tropical cyclone intensity and intensification. In this paper, TCHP change under global warming is presented based on 35 models from CMIP5 （Coupled Model Intercomparison Project, Phase 5）. As the upper ocean warms up, the TCHP of the global ocean is projected to increase by 140.6% in the 21st century under the RCP4.5 （＋4.5 W m 2 Representative Concentration Pathway） scenario, The increase is particularly significant in the western Pacific, northwestern Indian and western tropical Atlantic oceans. The increase of TCHP results from the ocean temperature warming above the depth of the 26~C isotherm （D26）, the deepening of D26, and the horizontal area expansion of SST above 26~C. Their contributions are 69.4%, 22.5% and 8.1%, respectively. Further, a suite of numerical experiments with an Ocean General Circulation Model （OGCM） is conducted to investigate the relative importance of wind stress and buoyancy forcing to the TCHP change under global warming. Results show that sea surface warming is the dominant forcing for the TCHP change, while wind stress and sea surface salinity change are secondary.

Distribution characteristics and source tracing of petroleum hydrocarbons in the northeastern South China Sea

In recent years,oil spills caused by human activities have occurred frequently,and the resultant oil pollution has received extensive attention worldwide.In this paper,a total of 50 water samples were collected from the northeastern part of the South China Sea,and total petroleum hydrocarbons(TPHs)and n-alkane content in the samples were analyzed by gas chromatography-flame ionization detector(GC-FID)technology.The petroleum hydrocarbon characteristic indices,such as carbon predominance index(CPI)and terrigenous/aquatic ratio(TAR),were calculated to trace the source of petroleum hydrocarbons.The measured value of TPHs ranged from 121.31-603.02μg/L.For surface waters,the TPHs in the no rthern coastal waters and the central waters were higher than that in the far shore.For ve rtical waters,the TPHs sharply decreased at first,and then increased slowly and finally reached a steady state.The n-alkanes in the water samples were concentrated in C10-C38,and they were mainly from terrestrial higher plant.The waters in the near shore,mid-layer and deep sea showed a strong reducing terrestrial characteristic,while the surface waters in the open sea showed an obvious oxidizing endogenous characteristic.