Ocean acidification and warming are occurring globally through increasing CO₂ absorption into the oceans, and impose two serious and imminent threats to the persistence of scleractinian corals and the reef ecosystem they construct. To evaluate the effects of ocean acidification and warming on the early life stages of the reef-building corals Acropora austera and A. intermedia, their larvae were incubated at a full cross design of two temperatures (about 28℃, about 30℃) and pCO₂ (about 570 μatm, about 1 300 μatm) for 8 d. There were no significant differences in rates of settlement. Larval mortality rates of two reef-building corals were unaffected in any treatments. High pCO₂ significantly reduced post-settlement survival of A. austera but not A. intermedia, with a 25.87% reduction in post-settlement survival in high pCO₂ compared to control. Our results show that larvae settlement and mortality rates of the reef-building corals A. austera and A. intermedia were unaffected by ocean acidification and warming, and high pCO₂ are more detrimental to mortality rates of juvenile A. austera than high temperature. Different species of juvenile corals exhibit species-specific response to ocean acidification and warming, with important implications for coral recruitment and even species structure composition of reef-building corals in the future ocean.

As one of the most abundant species of family Notothenioidei, rock cod (Patagonotothen ramsayi) plays an important role in energy transfer in the food web in the Patagonian Shelf. Currently, the work on feeding ecology of this species mainly bases on the conventional stomach content analysis, which only reflects short-term variation in feeding. Therefore, this study analyzed the distribution of fatty acids in three tissues (muscle, liver and gonad) of rock cod, and analyzed whether fatty acids in these tissues can characterize their feeding habits and transfer of diet. The results indicate that 27 kinds of fatty acids were detected in the tissues of rock cod. The storage and use of fatty acids in liver and gonad tissues are not suitable for indicating the diet of rock cod because they are involved in growth and reproduction. Compared to liver and gonad tissues, the longer renewal cycle of muscle tissue may better reflect its absorption of fatty acids from food. For the analysis of fatty acids in the muscle tissue of the rock cod in different size groups, it is inferred that the small-size rock cod (immature individual, 100−240 mm) mainly fed on planktonic organisms. The benthic feeding characteristics of rock cod increase with the increasing of size, and the feeding pattern transfer from planktonic feeding to planktonic-benthic feeding. In addition, due to the consumption of a certain amount of fishery discards by rock cod, the contribution rate of saprophytic food chain to predatory food chain is weakened. The results derive from this study further demonstrate that, compare to tissues of liver and gonad, the fatty acids of muscle tissue can be more suitable to indicate the food source of oceanic fish species.

The horizontal suspended and bed-load sediment transport in the bottom boundary layer were computed by applying a one-dimensional parameterized scheme to the in-situ data obtained from two stations in the Bohai Strait during a winter field investigation in 2018. In the parameterized scheme, a simplified one-dimensional advection-diffusion equation was used to calculate the vertical suspended sediment concentration in the bottom boundary layer. Aiming at verifying the reliability of the parameterization scheme, two models of bed shear stress calculation, four critical bed-shear stress methods and two advection-diffusion solutions were compared based on the observations. It showed that: (1) bed shear stress calculated by different models are fairly consistent; (2) the critical bed-shear stress is affected by sediment cohesive effects; (3) stratification effect of sediment concentration and the difference of critical bed-shear stress with different particle size fractions need to be considered solving the one-dimensional advection-diffusion equation. Based on the optimal parameterization obtained from the comparisons, sediment transport of the two stations was further calculated: (1) during resuspension events, the ratio of the horizontal suspended sediment flux within 5 meters above bottom accounting for the suspended sediment flux throughout the entire water column which is about 21% in T01 and 17% in T02 is significantly higher than the ratio of the water flux within the same layers; (2) the mean suspended sediment flux estimated by the parameterization scheme in winter is about 16% higher than the result estimated from the conventional method which ignores the vertical variation of suspended sediment concentration in the bottom boundary layer; (3) bed-load transport is generally 2 orders of magnitude smaller than the suspended load transport.

To recognize the environmental effects on underwater acoustic localization in deep sea and improve the measurement system performance against environmental variations, an simulation method for localization performance evaluation under different oceanographic conditions was presented, in which the sound filed calculation, error propagation and crossing solution were integrated by modelling, and the effects of seasonal environmental variation on localization performance were discussed in the case of Western Pacific. According to simulation results, when the receiving depth was near the surface, the sound channel showed different models in summer and winter, such that the accuracy was worse in summer influnced by seasonal thermocline and better in winter influnced by surface duct, the difference of root mean square error (RMSE) beyond 50 m; when the receiving depth was in the upper ocean, the localization performance had an obviously seasonal change caused by the active range of direct wave, and the accuracy was better in winter than that in summer, the difference of RMSE was 15−20 m; when the receiving depth was near the bottom, the better accuracy was obtained using reliable acoustic path, and the localization performance had little change with season. This work indicates that the seasonal environmental variation induces differences in the sound channel as well as the arrival acoustic information, the error propagation and crossing solution for the localization in the half convergence zone area of deep sea, then exert significant effects on localization performance as the receiving depth in the upper ocean.

Based on the direct turbulence observations in the Bohai Sea during September 2017, this study investigates the spatial distribution of turbulent mixing in the Bohai Sea and the associated influencing factors. The water column was weakly stratified during the observation period. As influenced by the freshwater input from Yellow River, relatively warm and fresh water was found in the Laizhou Bay. The typical south-north dual-core cold bottom water structure still exited in the central Bohai Sea during the observation period. The observed turbulent kinetic energy (TKE) dissipation rate ε ranged from 10⁻⁹ to 10⁻⁵ W/kg and statistically satisfied the lognormal distribution. Intensified mixing was found at the nearshore region of the Liaodong Bay and the Bohai Bay. The corresponding vertical eddy diffusivity was about 10⁻⁶～10⁻² m²/s. In the vertical direct direction, strong mixing occurred near the sea surface and bottom layers. Further analysis shows that the station-averaged TKE dissipation rate are positively related to the wind speed and barotropic tidal velocity. On the other hand, the dissipation rate and buoyancy frequency N satisfied the power function relationship of $\varepsilon = 2.0 \times {10^{ - 8}} + 3.0 \times {10^{ - 7}}{({N^2}/N_0^2)^{ - 5}}$ indicating that inhibition effect of stratification on turbulent mixing.

Salinity linear trends and their contributed dynamics processes in the tropical Pacific Ocean were investigated with the Argo salinity and temperature fields, current assimilations and atmospheric reanalysis datasets. The robust salinity anomaly event (SAE) occurred in the tropical Pacific Ocean during 2015−2017, which resulted possibly in the reversing of Argo salinity long-term trends. Such SAE was characterized as distinct regional discrepancies and vertical structures. Significant surface freshening occurred in the northern tropical Pacific (NTP) and Southern Ocean Convergence Zone (SPCZ), whose remarkable freshening maximum could reach 0.71−0.92 and covered the upper mixed layer. Another subsurface salinification in the southern tropical Pacific (STP) with the maximum of 0.46 was found around thermocline layer. Moreover, the salinity anomalies in SAE can expand from west to east along the isopycnal layers. Salinity advection and entrainment were exhibited as the fundamental dynamic processes to the SAE event in the tropical Pacific Ocean, while advection term acted as the major contribution to salinity variability. Both of the dynamic factors played important role on SAE features during the whole event in the NTP and later period in the SPCZ and STP. The surface freshwater flux and subsurface mixing induce by density compensation were also supplements to the SAE events in the NTP freshening and STP salinification respectively.

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.

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.