Resuspension and its distribution of sediment depend upon three interacting components namely the characteristics of the mobile sediment, the bed forms and the forcing hydrodynamics. A good understanding of the process of sediment resuspension is important in sediment transport. In this paper, in-situ measurements of wave, current, and suspended sediment concentration profiles in the marine ranching of Xiangyun Bay were carried out. The vertical distribution characteristics of suspended sediment in the bottom boundary layer under the wave-current action were analyzed. The results show that the resuspension of seabed sediments in the study area is controlled by storm-waves. The bottom shear stress under storm wave is 10−15 times of the critical shear stress of sediment, resuspension of sediment lags behind storm-wave for 2−3 hours. The type of vertical distribution of suspended sediment is "I" under small wave load, the vertical distribution of suspended sediment in the bottom boundary layer presents a power exponential function, which is "L" type under storm-wave. Bedforms evolved with wave and current action, and which affected the resuspension process of sediments. ${u_{*w}}{\rm{/}}{u_{*c}} = 1.00$ can be used as a criterion to distinguish the bedfroms under the dominant control of wave or current. The value of ${u_{*w}}{\rm{/}}{u_{*c}}$ under wave load is higher than that under the dominant control of wave, and the cutoff value between them increased with the increase of wave load.

Due to the influence of runoff and estuarine morphology, asymmetrical phenomena of hydrodynamics, suspended sediment concentration (SSC) and salinity occurs between the flooding and ebbing stage in the estuary. Such a phenomena also shows significant regional and seasonal differences. Based on hydrological survey in July 2013 and January 2014 in the Changjiang River Estuary, it is found that suspended sediment concentration in the branched channels of the Changjiang River Estuary has asymmetric characteristics, which varies with flood and dry season as well as spring and neap tide. In terms of spatial variability, there exists along channel difference, inter-channel difference as well as water colume difference. The evolution of the estuary controlls the overall SSC difference between the North Branch and South Branch. The flood and dry seasons affect the redistribution process of SSC in the estuary. Spring tides has a stronger impact on SSC asymmetry than that of neap tides. Theseasonal wave condition affect the SSC asymmetric distribution in the turbidity maximum zone of the estuary along the north-south direction. The high sediment concentration near the bottom contributes significantly to the SSC asymmetry between flooding and ebbing stages at the river mouth.

Based on the buoys data over the China offshore area during July 1, 2018 to August 6, 2018 collected by the Ministry of Natural Resources, three SST reanalysis products (OISST, OSTIA SST, RTG SST) were validated and compared through analyzing the mean bias, root mean square error (RMSE), correlation coefficient and standard deviation bias. The comparison results show that in the whole time, three SST reanalysis products we used are comparable to the buoys data. The mean bias and correlation coefficient between OSTIA SST dataset and buoy SST data is 0.12℃ and 0.94, better than OISST dataset (−0.85℃, 0.90) and RTG SST dataset (−0.17℃, 0.86). Compared with 80% buoys, the reliability of OSTIA SST dataset is higher than OISST dataset and RTG SST dataset significantly. During typhoon transit periods, absolute values of mean bias and RMSE (correlation coefficient) between OSTIA SST dataset and buoy SST data are smaller (larger) than RTG SST dataset and OISST dataset, which means that OSTIA SST dataset can capture the basic characteristics of SST over the China offshore area more accurately in severe sea conditions.

Jason-3 satellite was successfully launched on January 17, 2016, and was put on its nominal orbit on February 12, 2016. Jason-3 was flying in formation with Jason-2 only 1 minute 20 seconds, and was about 560 km from Jason-2. Jason-2 was moved to its new interleaved orbit on September 1, 2016. Two orbits were parallel to increase the spatial coverage of satellite observations. The objectives of this paper are to assess Jason-3 data quality and to estimate the altimetry system performance includes validation of Jason-3 data availability and data quality monitoring of Jason-3 and radiometer parameters. The objectives focused on comprehensive comparison of the parameters of the Jason-2 and Jason-3, accurately evaluated the consistency of the two altimeter parameters using the opportunity that the missions were on the same ground track during the formation flight phase, analyzed the ability and stability of the Jason-3 from the perspective of global data, verified Jason-3 data accuracy by self-crossover analysis and dual crossover analysis with Jason-2. From the results presented here, it is demonstrated that the Jason-3 mission fulfils the requirements of high precision altimetry. It allows continuing the observation of the sea surface height variations at the same or higher accuracy as Jason-1, Jason-2 and T/P. In addition, significant wave height quality of Jason-3 data is significantly better than the Jason-2.

Although the length of short array multi-channel streamers is limited,the absence of equipment for positioning and depth fixing, e.g., birds, magnetic compass, tail mark, etc., will bring some problems, such as inaccurate seismic geometric definition, to the subsequent procedure of data processing. In addition, different sinking depths without correction of depth fixing at different receiving sections along the short towing cable will destroy the relationship of the theoretical hyperbolic curve between time and distance. As to the short-array multi-channel seismic reflection data, therefore, we utilize the surveying navigation data to calculate the real shot track points, and then the interpolation algorithm weighted with inverse ratio of distance is employed to estimate the trajectory coordinates of the receiving points, which aids in obtaining the authentic geometric parameters of the total array. In order to resolve the distortion of time-distance curve caused by inconsistent depth of receiving cable, we calculate the theoretical reflecting positions of common mid-point (CMP) with hyperbolic curve and gauge the static correction of receiving arrays with different sinking depths. Finally, distortions of the reflection event caused by the non-uniform sinking depths of receiving array are eliminated by the fitting algorithm of static correction. The application of above processing processes to the short-array seismic reflection data collected in the Ross Sea, West Antarctica produces high-resolution stacked seismic reflection profiles, which provides great technical assistance for following work of geological interpretation.

Compared with shore-based GNSS-R technology, the airborne GNSS-R has the advantages of high spatial resolution, wide monitoring range, high-resolution monitoring of specific areas, and flexible height and azimuth adjustments. This paper mainly studies the airborne GNSS-R altimetry model, based on the shore-based GNSS-R code altimetry principle, corrects the atmospheric delay, antenna distance, etc., optimizes the airborne altimetry model, and uses the DTU10 global sea level average height and tide. The model verifies the accuracy of the onboard GNSS-R altimetry model. By analyzing the GNSS-R airborne data of the CSIC-IEEC in the Baltic Sea in Finland on November 11, 2011, the inversion of the experimental data at different elevation angles was successfully carried out, and the inversion of the sub-meter airborne sea surface height was successfully achieved. The conclusion that the elevation angle has a great influence on the accuracy of the altimetry results qualitatively analyzes the error range caused by the elevation angle. The results of this paper demonstrate the feasibility of sea level altimetry for airborne GNSS-R.

Kinetic dissolution and the reactive continuum model were combined to characterize the reactivity of iron (Fe) and phosphorus (P) in surface sediments of the Changjiang (Yangtze) River Estuary and the adjacent East China Sea. Two kinetic parameters, i.e., theoretical amounts (m ₀) and apparent rate constant (k) of reactive Fe, were extracted by fitting kinetic dissolution data to the reactive continuum model. Results showed that Fe(Ⅱ) phases occurred in all surface sediments studies, which could be ascribed to rapid reduction of highly reactive organic-bound Fe(Ⅲ) flocculated/precipitated to the sediments. It is inferred that Fe(Ⅱ) occurs mainly as FeCO₃ in both the Changjiang (Yangtze )River Estuarine sediments and the adjacent East China Sea sediments. The m ₀ and k values of Fe(Ⅱ) were controlled mainly by total organic carbon (TOC) contents and clay fractions. Simultaneous release of Fe(Ⅱ) and associated P (mainly exchangeable P and authigenic P) resulted in similar pattern of dissolution kinetics. Relative to P adsorbed on surfaces of Fe(Ⅱ) solid phases, coprecipitated P with Fe(Ⅱ) phases has higher m ₀ but lower k. In fine-grained sediments with high TOC contents, Fe(Ⅲ) oxides have lower m ₀ values but higher k in comparison with those in coarse-grained sediments with lower TOC contents, which is caused by different processes of Fe redox cycling. Overall, the dissolution reactivity of P associated with Fe(Ⅲ) phases is largely controlled by the reductive reactivity of Fe(Ⅲ) phases. Our kinetic characterization indicates that flocculation/precipitation has caused reactive Fe enrichment in the estuarine sediments, occurring mainly in a narrow zone of low salinity, but the enrichment could not be revealed by conventional Fe speciation.

Yellow Sea is a semi-enclosed marginal sea that is significantly impacted by human activities. One of the major characteristics of Yellow Sea is the long-term existence of intensive cold water mass in summer. In order to study the cycling of particulate nitrogen in summer Yellow Sea, we analyzed the organic carbon and nitrogen content and isotope of the suspended particulate matter and of the surface sediments in South Yellow Sea in summer, 2016. We focus on the spatial variances in particulate nitrogen content, isotope character and the controlling factors respectively in coastal waters and cold water masse realm. In the coastal waters, the particulate nitrogen (PN) are comparatively higher and the vertical variances of nitrogen isotope (δ¹⁵N_PN) are small, while total nitrogen content (TN) in coastal sediment are lower and the nitrogen isotope (δ¹⁵N_TN) are mostly negative. In central south Yellow Sea where cold water masses exists, the PN is characterized of low content, significant vertical variances in δ¹⁵N_PN, while TN in sediment are characterized of high content and positive δ¹⁵N_TN. We further run bottom critical shear stress simulation and environmental factors analysis, and found out that the spatial variances of particulate nitrogen content and nitrogen isotopes in the South Yellow Sea was mainly controlled by the vertical mixing in water column, benthic boundary dynamic processes, and partially contributed by re-mineralization and terrestrial PN input.

Based on the seven comprehensive surveys in the coastal area of Rushan Bay in summer of 2009 and 2014, the distribution of nitrogen and phosphorus nutrients and nutrient structure were analyzed, and the budgets of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) were estimated based on the water balance calculated by Princeton Ocean Model (POM). The results show that the high concentrations of DIN and DIP in adjacent area of Rushan Bay in summer appears in the mouth area of Rushan Bay. Their concentrations and distributions are influenced by the terrestrial inputs, tides and currents significantly. The DIN and DIP effluxes from the sediment to the overlying water at the sediment-water interface result in the higher concentrations of DIN and DIP in the bottom water than those in the surface water. The budget of DIN shows that internal cycling is the dominant source of DIN for the primary production, accounting for 86% of uptake by primary production, followed by water exchange (11%), and benthic efflux (3%); the removal of DIN in the water column is dominant by sedimentation (80%), export to the offshore (16%), and denitrification (4%). The DIP budget shows that internal cycling in the water column is the dominant source of DIP for the primary production, accounting for 91% of uptake by primary production, followed by water exchange (9%), and benthic efflux (lower than 1%); the removal of DIP in the water column is also dominant by sedimentation (67%) and export to the off shore by water exchange (33%). Based on the budgets of DIN and DIP, internal recycling is the dominant source for both of DIN and DIP supplies in the coastal water column, and the burial efficiency of P is higher than N into the sediment in the area off Rushan Bay. However, the different nutrient structure between external and internal sources of the study area would result in a long-term effect on the nutrient balance and primary production due to the differential budget of DIN and DIP.

Transient electromagnetic method (TEM) is an effective method for deep-sea polymetallic sulfide exploration. High-grade metal components in seafloor polymetallic sulfides cause extremely strong induced polarization effects and have a significant impact on transient electromagnetic response. In this paper, the inductive effects of deep-sea polymetallic sulfides were analyzed through laboratory measurement and numerical simulation. First, systematic electrical tests were carried out on rock ore samples from the hydrothermal vent fields on the southwest Indian Ocean Ridge. The complex resistivity of typical sulfides has a phase shift of up to 160 mrad in the frequency domain. The time domain and frequency domain measurements show that the polarizability parameter is a good indicator to distinguish sulfide minerals and surrounding rocks. Using the Cole-Cole model to interpret the complex resistivity to obtain the characteristic parameters of complex resistivity, the relationship between parameters and the composition and structure of the massive sulfide was analyzed, and the typical sulfides were classified based on the polarizability parameter. The induced polarization parameters of the typical sulfides were used to calculate the transient electromagnetic response of the layered medium, which show that the influence of induced polarization effect can be observed simultaneously in the best observation window of the TEM response of the deep-sea polymetallic sulfide deposit. Although the transient response is distorted in the late stage of the acquisition window, in the early stage of signal reception, the induced polarization effect effectively enhances the detection capability of the TEM for deep-sea polymetallic sulfides, which provides an explanation basis for the transient electromagnetic measurement data.