Fronts, baroclinic transport, and mesoscale variability of the Antarctic Circumpolar Current (ACC) along 115°E are examined on the basis of CTD data from two hydrographic cruises occupied in 1995 as a part of the World Ocean Circulation Experiment (WOCE cruise I9S) and in 2004 as a part of CLIVAR/CO₂ repeat hydrography program. The integrated baroclinic transport across I9S section is (97.2×10⁶±2.2×10⁶) m³/s relative to the deepest common level (DCL). The net transport at the north end of I9S, determined by the south Australian circulation system, is about 16.5×10⁶ m³/s westward. Relying on a consistent set of water mass criteria and transport maxima, the ACC baroclinic transport, (117×10⁶±6.7×10⁶) m³/s to the east, is carried along three fronts:the Subantarctic Front (SAF) at a mean latitude of 44°-49°S carries (50.6×10⁶±13.4×10⁶) m³/s; the Polar Front (PF), with the northern branch (PF-N) at 50.5°S and the southern branch (PFS) at 58°S, carries (51.3×10⁶±8.7×10⁶) m³/s; finally, the southern ACC front (SACCF) and the southern boundary of the ACC (SB) consist of three cores between 59°S and 65°S that combined carry (15.2×10⁶±1.8×10⁶) m³/s. Mesoscale eddy features are identifiable in the CTD sections and tracked in concurrent maps of altimetric sea level anomalies (SLA) between 44°-48°S and 53°-57°S. Because of the remarkable mesoscale eddy features within the SAF observed in both the tracks of the cruises, the eastward transport of the SAF occurs at two latitude bands separating by 1°. Both the CTD and the altimetric data suggest that the mesoscale variability is concentrated around the Antarctic Polar Frontal Zone (APFZ) and causes the ACC fronts to merge, diverge, and to fluctuate in intensity and position along their paths.

The ocean general circulation model for the earth simulator (OFES) products is applied to estimate the transports of the Mindanao Current (MC) and the Mindanao undercurrent (MUC) and explore the relation between them on seasonal scale. In general, the MUC is composed of the lower part of the Southern Pacific Tropical Water (SPTW) and Antarctic Intermediate Water (AAIW). While the deep northward core below 1 500 m is regarded as a portion of MUC. Both salinity and potential density restrictions become more reasonable to estimate the transports of MC/MUC as the properties of water mass having been taken into consideration. The climatological annual mean transport of MC is (37.4±5.81)×10⁶ m³/s while that of MUC is (23.92±6.47)×10⁶ m³/s integrated between 26.5σ_θ and 27.7 σ_θ, and (17.53±5.45)×1010⁶ m³/s integrated between 26.5 σ_θ and 27.5 σ_θ in the OFES. The variations of MC and MUC have good positive correlation with each other on the seasonal scale: The MC is stronger in spring and weaker in fall, which corresponds well with the MUC, and the correlation coefficient of them is 0.67 in the OFES. The same variations are also appeared in hybrid coordinate ocean model (HYCOM) results. Two sensitive experiments based on HYCOM are conducted to explore the relation between MC and MUC. The MUC (26.5< σ_θ< 27.7) is strengthening as the MC increases with the enhancement of zonal wind field. It is shown, however, that the main part of the increasement is the deeper northward high potential density water (HPDW), while the AAIW almost remains stable, SPTW decreases, and vice versa.

In this paper, effort is made to demonstrate the quality of high-resolution regional ocean circulation model in realistically simulating the circulation and variability properties of the northern Indian Ocean (10°S-25°N, 45°-100°E) covering the Arabian Sea (AS) and Bay of Bengal (BoB). The model run using the open boundary conditions is carried out at 10 km horizontal resolution and highest vertical resolution of 2 m in the upper ocean. The surface and sub-surface structure of hydrographic variables (temperature and salinity) and currents is compared against the observations during 1998-2014 (17 years). In particular, the seasonal variability of the sea surface temperature, sea surface salinity, and surface currents over the model domain is studied. The high-resolution model's ability in correct estimation of the spatio-temporal mixed layer depth (MLD) variability of the AS and BoB is also shown. The lowest MLD values are observed during spring (March-April-May) and highest during winter (December-January-February) seasons. The maximum MLD in the AS (BoB) during December to February reaches 150 m (67 m). On the other hand, the minimum MLD in these regions during March-April-May becomes as low as 11-12 m. The influence of wind stress, net heat flux and freshwater flux on the seasonal variability of the MLD is discussed. The physical processes controlling the seasonal cycle of sea surface temperature are investigated by carrying out mixed layer heat budget analysis. It is found that air-sea fluxes play a dominant role in the seasonal evolution of sea surface temperature of the northern Indian Ocean and the contribution of horizontal advection, vertical entrainment and diffusion processes is small. The upper ocean zonal and meridional volume transport across different sections in the AS and BoB is also computed. The seasonal variability of the transports is studied in the context of monsoonal currents.

In June 2003 and 2006 concentrations of nutrient were determined in the Changjiang Estuary. The data indicated that phosphate and nitrate did not behave conservatively in the estuary, but silicate behaved conservatively. An important mobilization of phosphate and nitrate was observed from the river up to halfway in the estuary. Both input flux (from river to estuary) and output flux (from estuary to coastal zone) of phosphate, silicate and nitrate were calculated from statistical interpretations of the salinity profiles. There was a large discrepancy between input and output fluxes of phosphate and nitrate. The river fluxes of silicate, phosphate and nitrate (f_r) are augmented 5.3%, 28.9% and 36.6% in June 2003 and 1.0%, 62.5%, 31.7% in June 2006 by internal inputs (f_i). The phosphate and nitrate fluxes are enhanced through the estuarine process, while silicate flux is unaltered. The authors present some long-term data for nutrient concentrations and the ratios of silicon to nitrogen to phosphorus in the Changjiang Estuary. Silicate level falled in the last two decades, while concentration of nitrate increased. Phosphate concentration had no significant change.

Based on the field data including tidal current,suspended sediment concentration,grain size of surface sediments,the transport mechanism and movement trend of sediments are analyzed using the method of flux decomposition and Grain Size Trend Analysis.The results show that the concentration and flux of suspended sediments decrease sharply from the Hangzhou Bay to the offshore area.The suspended sediment transport is mainly controlled by advection transport including average current transport and Stokes drift-induced transport and the gravitational circulation transport.The surface sediments are transported from the entrance of the Hangzhou Bay to the offshore area in general; meanwhile,the sediment transport has two obvious transport trends in the offshore area.The interaction of tidal currents,residual currents,the East China Sea coastal current,Taiwan Warm Current and wind waves appear to play important roles in the sediment transport.Furthermore,the sediment distribution and transport are significantly affected by the Zhoushan Archipelago.

By introducing the wave-induced Coriolis-Stokes forcing into ageostrophic motion equation, the Eulerian transport is modified by the wave-induced Stokes drift. The long-term mean contributions of the Stokes transport with remotely generated swells being included to the ageostrophic transport are analyzed using the ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis data. The ratio of Stokes transport to Ekman transport in north-south (N-S) direction can reach a maximum of over 50% in the subtropical region. The preliminary influence of the Stokes transport on the North Pacific gyre is all year persistent, while the effect on the North Atlantic gyre is only obvious in boreal winter and early spring.

The major difference between the two concepts,"transport" and "propagation",of wave energy is expounded in both mathematical expression and basic idea,and the mechanism of energy transport and the meaning of group velocity for water waves are discussed in this paper.A number of important conclusions are given from the present discussion,which are favourable to clarifying some confusion or obscurity as such concepts as energy transport,propagation and group velocity are used in the study of water wave theory and its applications.

Four trawl-resistant bottom mounts, with acoustic Doppler current profilers (ADCPs) embedded, were deployed in the Karimata Strait from November 2008 to June 2015 as part of the South China Sea-Indonesian Seas Transport/Exchange and Impact on Seasonal Fish Migration (SITE) Program, to estimate the volume and property transport between the South China Sea and Indonesian seas via the strait. The observed current data reveal that the volume transport through the Karimata Strait exhibits significant seasonal variation. The winter-averaged (from December to February) transport is -1.99 Sv (1 Sv=1×10⁶ m³/s), while in the boreal summer (from June to August), the average transport is 0.69 Sv. Moreover, the average transport from January 2009 to December 2014 is -0.74 Sv (the positive/negative value indicates northward/southward transport). May and September are the transition period. In May, the currents in the Karimata Strait turn northward, consistent with the local monsoon. In September, the southeasterly trade wind is still present over the strait, driving surface water northward, whereas the bottom flow reverses direction, possibly because of the pressure gradient across the strait from north to south.

Based on the output data from 1997 to 2000 obtained by the MITgcm's (general circulation model) adjoint assimilation method, volume, heat and salt transports through the Luzon Strait are calculated. The results indicate that there are obvious different characteristics between 1997 and 1998~2000 on the transports through the Luzon Strait. During 1997, theLuzon Strait had a mean net westward transport of 3.93×10⁶ m³/s with a maximum transport of 7.34×10⁶ m³/s in October. During 1998~2000, the Luzon Strait possessed an annual mean eastward transport of 0.93×10⁶, 1.80×10⁶ and 1.00×10⁶ m³/s respectively with a maximum eastward transport of 4.10×10⁶/3.31×10⁶ m³/s in July 1998/1999 and 2.06×10⁶ m³/s in April 2000, respectively. Moreover, the transports in 1997 indicated a difference from the other years, i.e.,that the ranges of westward inflows expanded more obviously to north of the Luzon Strait and downwards exceedingthose of the other years. The westward inflows expanded horizontally to the north part of the Luzon Strait until 21°N.

Water circulation and sediment transport in the Beibu Gulf are important for its environmental protection and resource exploitation. By employing the Regional Ocean Modeling System (ROMS), we studied the seasonal variation of circulation, sediment transport and long-term morphological evolution in the Beibu Gulf. The simulation results show that the circulation induced by tide and wind is cyclonic both in winter and summer in the gulf and that the wind-driven circulation is stronger in winter than that in summer. The sediment concentration is higher in the Qiongzhou Strait, west of the Hainan Island and the coast of Vietnam and the Leizhou Peninsula. The sediment is transported westwards in winter and eastwards in summer in the Qiongzhou Strait. The west entrance of the Qiongzhou Strait is dominated by westward transport all the year round. The sediment discharged by rivers is deposited near the river mouths. The simulated result demonstrates that the sediment transport is mainly controlled by tidal induced bottom resuspension in the Beibu Gulf. Four characteristics are summarized for the distribution patterns of erosion and deposition. (1) The erosion and deposition are insignificant in most area of the gulf. (2) Sediment deposition is more significant in the mouths of Qiongzhou Strait. (3) The erosion is observed in the seabed of Qiongzhou Strait. (4) Erosion and deposition occur alternatively in the west of Hainan Island.