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A preliminary assessment of the Pacific Equatorial Intermediate Currents (EICs) in five ocean models outputs (OFES, LICOM, HYCOM, ECCO2 and SODA) were conducted according to the spatial and temporal features using observation data which was calculated from Argo trajectories. The EICs in Argo currents field are mainly composed of the alternating east-west zonal jets. In the east-west direction, the currents are strong in the western but weak in the eastern, in the south-north direction, the currents are strong in the southern but weak in the northern. Besides, there are seasonal variations and the phase of seasonal variations is characterized by westward propagation and meridionally symmetrical on the equator. The assessment results show that SODA is the best dataset in these five models, all the characteristics are almost consistent with the observation. The second is ECCO2, the flow field is almost consistent with the observation except the kinetic energy. Then comes the OFES, LICOM and HYCOM, all of them are able to simulate the structures of the alternating zonal jets.

The tidal residual current in the adjacent area of Sanggou Bay plays an important role in material transport. However, due to the lack of observation data, the overall spatial pattern of the tidal residual current in this area is still unclear. 22 sets of observational data and high-resolution numerical simulation data of the ocean current were used to analyze the overall spatial characteristics of tidal residual currents and to reveal its formation mechanism. The tidal residual currents within the Sangou Bay are generally weak, while in the areas near the three headlands (Lidao, Xunshan and Chushan), the tidal residual currents show significant pair of eddies. To the northern part of each headland, there is a cyclonic tidal residual eddy; while to the southern part of each headland, there is an anticyclonic tidal residual eddy. The pair of eddies near the headlands of Lidao and Chushan are much stronger and cover wider area than those of Xunshan. Dynamic diagnosis based on the residual vorticity equation shows that the tidal residual eddies are mainly induced by the horizontal shearing due to the lateral boundary friction, the bottom friction stress curl only affects the tidal residual eddies near the headland of Lidao, and the effect of potential vorticity conservation is not significant in the formation process of the all three pair of the tidal residual eddies.

Distribution of eddy originations and characteristics of eddies in summer and winter in the Bay of Bengal (BOB) from 1993 to 2017 were analyzed based on Mesoscale Eddy Trajectory Atlas Product provided by AVISO. Seasonal variabilities of mesoscale eddies were found mainly in the western BOB, the Andaman Sea and the southern BOB. Eddies in the Andaman Sea distribute from north to south with order of “anticyclones-cyclones-anticyclones” and “cyclones-anticyclones-cyclones” in winter and summer respectively. Growth of eddies has seasonal variabilities and varies from different regions. Eddies in the western BOB intensify rapidly but vanish slowly in summer. Sri Lanka cold eddies intensify slowly but vanish rapidly. Amplitude and radius of eddies are different in different regions. Amplitude and radius of anticyclones are larger than those of cyclones whenever in summer or winter in the western BOB. Radius of anticyclones is larger than that of cyclones near the Southwest Monsoon Current. While, amplitude of anticyclones is smaller than that of cyclones. Amplitude and radius of eddies northernmost are the largest whenever in summer or winter in the Andaman Sea. Eddies with lifetime about 30-40 days are the largest number in the Bay of Bengal. Eddies with long lifetime mainly distribute in the western BOB.

The phenomenon of “double peak” of tidal water level in Daya Bay and Dapeng Bay was reproduced by means of the measured data, and it is determined that the abnormal growth of shallow water tide is the main cause of the phenomenon, among which the one-quarter-day tide and the one-sixth-day tide played a crucial role. The high-resolution hydrodynamic model of Daya Bay and Dapeng Bay was constructed by using the SCHISM model. The simulation shows that in the open sea outside Daya Bay and Dapeng Bay, tidal type is irregular diurnal tide in the eastern sea, tidal type is irregular semidiurnal tide in the western sea and two bays. The pattern of current is irregular semidiurnal currents in study area. The difference of hydrology between the two adjacent bays is directly caused by the deformation process of one-quarter-day and one-sixth-day tide in Daya Bay and Dapeng Bay. Through the numerical experiments of building different bottom friction intensity, eliminating bottom topography and changing water depth, it is shown that whether the direction of split tide propagation is consistent with the direction of shallower water depth is the fundamental reason that leads to the different tidal wave deformation in two bays.

The characteristics of tropical-cyclone(TC) activities over the western North Pacific during 1951-2016 were analyzed using three TC best track datasets(CMA, JTWC and RSMC). The consistent conclusions in three datasets are as follows: TCs mainly occurred in the latitude of 10°N-25°N. Before 1980, there was a southward latitude shift of TC position points, while it was the opposite after 1980. The TC translation speed was mostly distributed in the 2~6 m/s, and TCs significantly sped up near 25°N. The TC translation speed had a significant decrease trend before 1980. The maximum wind speed was mainly distributed in the range of 10~15 m/s, and it decreased before 1980. The radius of maximum wind speed was relatively smaller in the region with larger maximum wind speed. The radius of maximum wind speed of TCs and typhoons decreased by 0.46 km and 0.54 km per year respectively during 2001-2016. The results of CMA and RSMC were highly consistent, while the results of JTWC were different from them to some extent. The difference between the three datasets had a great influence on the change of TC intensity and the numbers of position points, but had a little influence on the change of the TC location and translation speed.

In order to solve the problem that there is a large deviation in retrieving SST by using reanalysis data of NCEP and Radiative Transfer Equation Algorithm, taking HJ-1B SST retrieval as an example and starting from the correction of the atmospheric transmittance, two improved Radiative Transfer Equation Algorithm: algorithms of the Center Point Algorithm and the Mean Point Method are proposed, and they are verified by MODIS SST and buoy SST. The two improved algorithms have improved the atmospheric transmittance deviation and HJ SST retrieval deviation significantly, and both HJ SST and MODIS SST show significant consistency. The MODIS SST verification shows that the average deviation and mean square error of the two improved algorithms are about 0.5 ℃. The buoy SST verification shows that the Mean Point Algorithm has higher retrieval accuracy, which average deviation is 0.55 ℃, the average deviation of the Center Point Algorithm is 0.81 ℃.

The fitting depth and calculated interval velocity will be inaccurate when the time-depth fitting of vertical seismic profile (VSP) data is applied to deep strata. In this study, polynomials and power functions were used to fit the time-depth relation based on VSP data from 41 drilling holes in the East China Sea Shelf Basin. The applicability of the fitting in deep strata was analyzed by analyzing the seismic velocity volume data and seismic profiles. The three-dimensional seismic velocity volume from migration has a maximum depth of 8 s in two-way travel time (TWT). The average fitting depth from the quadratic polynomial is 9.2% higher and the average interval velocity is 36.2% higher, respectively, whereas the power fitting depth and interval velocity are 28.9% lower and 35.6% lower, respectively in the deep strata (TWT=8 s), where the seismic velocity volume data shows that the average depth and interval velocity at 41 drilling holes are 18 140 m and 6 208 m/s, respectively. To solve this problem, a segmented fitting model was proposed, in which the interval velocity increase turning point of the VSP data was firstly identified, then the quadratic polynomial function was used to fit the VSP data above the turning point and the power function was used to fit the VSP data beneath the turning point. At TWT=8 s, the errors of the average fitting depth and interval velocity are reduced to 3.3% and 4.7%, respectively. The segmented fitting model shows that the average fitting depth and interval velocity are 27 516 m and 7 334 m/s, respectively, and these values basically are consistent with the observed Moho depth(TWT=11 s) in the seismic section of the study area. The segmented fitting method can significantly improve the accuracy of time-depth conversion of the strata, especially at large depths.

The preparation of standard reference material for five heavy metals in low salinity seawater was studied, which was prepared by volumetric method using the diluted seawater from oceans. The statistical results for each metal indicated that the homogeneity and stabilities were very well at 95% confidence level. Using three analytical methods including atomic absorption spectrophotometry (AAS), inductively coupled plasma mass spectrometry (ICP-MS), and anodic stripping voltammetry (ASV) the characterization was determined by a total of 9 laboratories qualified by China Metrology Accreditation (CMA). Certified standard materials were used for metrological traceability. The total average value of 9 laboratories measurements which satisfied statistical requirements was taken as the standard value. The results of standard values and uncertainties were Cu 15.2 ± 0.7 μg/L, Pb 15.3 ± 0.7 μg/L, Zn 98.9 ± 4.7 μg/L, Cd 2.02 ± 0.10 μg/L, and Cr 15.3 ± 0.6 μg/L, respectively. The developed standard reference material can be used for quantity transfer and quality control of heavy metals analysis in low salinity seawater from near shore and estuary areas.

The Free-Fall Penetrator(FFP) is a new type of in-situ measurement equipment for seabed sediments, which is used for in-situ investigation of engineering properties of seabed sediments. Based on the self-developed FFP equipment, field tests were carried out at two stations in the Yellow Sea to analyze the influence of probe size on judging sediment properties. The results show that the probe size has different effects on the determination of penetration depth, penetration resistance and sediment type in different sediments. In fine sediments the probe size has less influence of penetration depth and the penetration resistance. When delineating geological stratification, smaller diameter probes can reflect more subtle changes in penetration resistance. There is more obvious influence of the probe size in coarse sediments. The larger size probe makes the bigger penetration resistance, and the penetration depth is reduced. Depending on the standardized depth and hardness factor, coarse sediments and fine sediments can be distinguished. The size of the probe is increased in the coarse sediment, the hardness factor is reduced, which is advantageous to refine the type of deposit.

Taking Jinshanzui-Longquangang marginal shoal in the northern Hangzhou Bay as the study area, based on the measured and chart data from 1989 to 2014, we analyzed the topographic change of beach section and the variation characteristics of erosion and deposition of regional beach section along the Jinshanzui to Longquangang(JSZ-LQG) segment. The results showed that during study period there was relative stable eroded deepen channel in the study area, and the scouring and silting of the nearshore seabed showed a "fluctuating" law. The shallow area above 5 m water depth(2014) presented accreted patterns, meanwhile, seabed below 5 m water depth(2014) showed a general scouring trend since 1989. Moreover, variation of sediment discharge into the Yangtze River is an influencing factor of erosion/deposition in the study area. The typhoon waves, movement of the erosion and accretion sand body induced complexity in erosion and accretion in seabed of the JSZ-LQG segment.