Based on the hybrid detection method for ocean mesoscale eddy, this paper uses the measured data to verify the detected boundary and center of eddy, and draws the following conclusions. (1) By diagnosing the angle between the detected boundary and the measured current vector, the results show that the detected boundary of eddy can basically reflect the current state of the actual eddy. (2) The center of detected eddy is compareed with the center that inversed by the measured current and temperature data. The results show that the detected center of eddy is basically consistent with the inversed center. Furthermore, by comparing the fitting effect of circle and ellipse to the detected boundary of eddy, the results show that the fitting accuracy of ellipse is higher than that of circle.

As a kind of coastal accumulation body in high-energy environment, natural gravel beach is a good coastal protection barrier due to its coarse particle size and large porosity. The gravel morphology is an important parameter to understand the gravel formation process, but it is difficult to obtain the quantitative parameters of a large number of gravels quickly and accurately. In this study, we surveyed three gravel beaches (Jiuzhangya, Yueyawan, Changtan) in the Beichangshan Island, four gravel beaches (Xianjingyuan, Linhai, Changshanwei and Mingzhuguangchang) in the Nanchangshan Island in the Shandong Province. We measured beach profile, collected gravel samples and took gravel images. Using the software ImageJ for digital image measurement in situ without interference, we can quickly obtain a large number of gravel morphologic parameters, including particle size, grinding roundness and shape ratio. The results show that the range of the particle size is 4−79 mm, which was mainly pebbles. The average particle size of the beach in the Beichangshan Island is slightly smaller than that in the Nanchangshan Island, with the largest average particle size of gravels in the Jiuzhangya Beach of the Beichangshan Island and the smallest one in the Xianjingyuan Beach of the Nanchangshan Island. From beach berm to the high tidal line, the average particle size decreases gradually, but increases at waterline. The range of roundness of gravel is 0.59–0.75, and the grade is round. The gravel beaches have reached a relatively mature stage based on roundness, with the best roundness in the Yueyawan Beach and the worst roundness in the Changtan Beach of the Beichangshan Island. The gravel roundness increases from land to sea. The shape ratio ranges from 1.36 to 1.77, which is negatively correlated with the gravel roundness (R²=0.98). The gravel gradually changed from long strip to elliptic shape from land to sea. The gravel beaches morphology of the Changshan Island is affected by the provenances, dynamic conditions and human activities. The slope range of the gravel beach in the study area is 16%−35%, and they are positively correlated with the gravel particle size.

The modern Zhujiang River Delta has experienced the formation and evolution from drowned valley to delta, which is rich in regional characteristics. The research on the Zhujiang River Delta in the past hundred years is summarized into four paradigms: historical description, field investigation-scientific reasoning, instrument applied-discipline theory and “dynamic-sedimentary-morphologic” scale-crossing paradigm. Each illustrated by superb examples and documented. Based on the research of the authors and his team, this paper puts forward several propositions concerning the formation and evolution of the Zhujiang River Delta, which are substantially different from the existing literature, and makes necessary differentiation and analysis from multiple perspectives, including the millennial-scale changes of coastline since the transgression maximum, the mode of formation and evolution of the modern Zhujiang River Delta and the development and its mechanism of the major channels of the network in the delta. Finally, the approache of interdisciplinary, scale-crossing and time-space quantification concerning delta research are briefly discussed.

The risk assessment and zoning of submarine landslides can guide the site selection and risk prevention of offshore engineering facilities. In this paper, an unsupervised machine learning spectral analysis algorithm was used to evaluate the risk of submarine landslides in the Chengdao sea area of the Yellow River Estuary. A model of submarine landslides risk assessment with 9 input parameters, 4 output parameters and 0.08 as kernel function parameters is constructed. By using this model, the study area can be divided into 4 parts: high, quite high, quite low and low risk of submarine landslide. The comparison between the evaluation results and the distribution characteristics of geological environment factors show that the most important factors are the type of seafloor sediment and hydrodynamic action, and the most important trigger factor is liquefaction. The analysis results of model parameters present that the evaluation results with slightly lower accuracy can be obtained by reasonably simplifying the input factors, and the kernel function parameter is important index affecting the evaluation accuracy. The above research shows that the unsupervised machine learning algorithm can be well used in the risk assessment of submarine landslides, and the richness and accuracy of data categories are important factors affecting the assessment accuracy.

Based on the WRF (Weather Research and Forecasting Model) and its three-dimensional variational data assimilation system, the numerical simulation and Doppler radar data assimilation are conducted with the data of GFS (Global Forecasting System) and JMA (Japan Meteorological Agency) reanalyses as the initial conditions respectively. The impact of assimilation radar data in different background fields on the initial typhoon field, internal structure and forecast were investigated based on the super typhoon case Saomai in 2006. The results show that, both experiments with GFS and JMA data are able to enhance the typhoon initial winds field at 700 hPa and geopotential height field at 500 hPa after assimilating radar observations. The improvements in terms of the root-mean-square error during the 3 h during the data assimilation cycling, the minimum sea level pressure, and the thermal and dynamic structure from the JMA tests are more significant than that with GFS data. The forecast skills for the precipitation, the typhoon track, and the intensity are also noticeable with JMA data by correctly predicting the precipitation location in the front of typhoon.

Himawari-8 is a new generation geostationary meteorological satellite launched by the Japan Meteorological Agency, and provides the important observation data for merging hourly sea surface temperature (SST). This paper uses the optimal interpolation method to provide the hourly Northwest Pacific SST based on the Advanced Himawari Imagery(AHI) SST, the Global Change Observation Mission-Water (GCOM-W1) Advanced Microwave Scanning Radiometer 2 (AMSR2) SST and North-East Asian Regional–Global Ocean Observing System (NEAR-GOOS) SST. The diurnal SST variation and the bias between multi-source SSTs are the two significant factors affecting the accuracy of hourly SST fusion products. In order to make full use of SST at the adjacent time and improve the accuracy, a diurnal variation model of Himawari-8 AHI SST is established by using the matchup data set, which contains simultaneous Himawari-8 AHI SST and European Centre for Medium-Range Weather Forecasts wind data at the same location. In addition, a bias correction method based on Poisson’s equation is applied to correct GCOM-W1 AMSR2 SST biases relative to the AHI SST. The experimental results show that the diurnal warming calculated by the hourly SST fusion product is closely related to sea surface wind speed, which indirectly confirms the accuracy of the hourly SST fusion products. The root mean square difference and bias between the hourly SST fusion product and NEAR-GOOS SST are 0.89℃ and 0.09℃, respectively. The results show that the hourly SST fusion product is basically consistent with the in situ SST.

The sea surface temperature(SST), salinity(SSS), dissolved oxygen (DO), chlorophyll a(Chl a) and surface partial pressure of carbon dioxide(pCO₂) was determined by underway measurement system in the Qiongzhou Strait in summer 2011 and 2014, and the spatiotemporal variations of pCO₂ were analyzed and its control factors were explained. The averages of pCO₂ in surface sea water were (516±29) μatm and (533±15) μatm, sea-air CO₂ fluxes were (8.4±1.7) mmol/(m²·d) and (4.5±0.4) mmol/(m²·d) in summer 2011 and 2014, the Qiongzhou Strait acted as strong atmospheric CO₂ source and was more higher than the adjacent and similar sea areas. The upwelling forced the CO₂-enriched subsurface water to intrude the surface water and elevated pCO₂ in the east mouth, also promoted biological productivity and absorbed CO₂ from sea water, and also made the pCO₂ drop and DO rise sharply in the vicinity of west mouth in summer 2011. The upwelling was weak in east mouth and vertical mixing was strong along ship-track in summer 2014, the distributions of pCO₂ and DO were obviously different from that in summer 2011. Narrow channel effect was significant in the middle of Qiongzhou Strait, high water transportation speed with strong mixing resulted in weak photosynthetic activity, they altogether maintained high pCO₂ in summer 2011 and 2014.

The qualitative and quantitative analyses on betaine lipids of microalgae were conducted by means of the quadrupole flight time ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-Q-TOF-MS) using electron spraying ionization. As a result, 133 betaine lipids including 53 DGCC, 41 DGTS and 39 DGTA were identified from 14 species of microalgae in four major phyla. DGCC was the dominant betaine lipid in dinoflagellates and haptophytes, while DGTS was the main betaine lipid in chlorophytes. There were two main types of betaine lipid in diatoms: DGCC in centric diatom and DGTA in pennate diatom. The differences of fatty acid of betaine lipid in marine microalgae were only observed at the phyla and class levels, but at lower taxonomic levels the differences were less stable. DGCC existed in diatoms, dinoflagellates and chlorophytes, which contained C14−C18 saturated and unsaturated fatty acids and C20 and C22 polyunsaturated fatty acids. The difference in DGCC is that saturated C14−C18 fatty acids existed in dinoflagellates, while the fatty acids of odd carbon numbers C19 occurred only in diatoms. The results of description and molecular characterization of betaine lipid in microalgae can be served in future investigation in chemotaxonomy, physiology, ecological role of microalgae and functional properties of these phosphorous-lacking polar lipids.

In this paper, the time series analysis model ARIMA (1, 2, 0) was applied to simulate and predict the stock of small yellow croaker (Larimichthys polyactis) based on the monitoring catches data of canvas stow net in the southern Yellow Sea from 2003 to 2014 and verified by the monitoring catches data of 2015 and 2016. The results showed that the simulated and actual values for the catch yield from 2003 to 2014 were correlated significantly (p<0.05) and the correlation coefficient was 0.881. The relative error between predicted and actual value in 2015 and 2016 were respectively 6.73% and 22.75%, the overall relative error was 14.74% and the regression equation fitted the real situation better, which illustrated that the time series analysis model ARIMA (1, 2, 0) can be applied to simulate the catches trend of L. polyactis and predict the catch stock, especially superior in short-term forecasting. However, in any case the fixed model of L. polyactis is not always suitable for all data analysis, and the values of p, d and q in ARIMA model are considered to be variable according to different time series. Therefore, the optimal values of p, d and q should be determined based on the guidance and analysis of relevant theories in order to avoid copying directly the fixed model.

Increasing atmospheric CO₂ concentration leads to ocean acidification, which might affect phytoplankton to varying degrees. Phytoplankton in coastal waters may be affected by seawater acidification and alkalization. In this experiment, Thalassoosira punctigera (diatom) was used to investigate its growth, photosynthesis, dark respiration, cell size, chlorophyll a content, biogenic silica content and chlorophyll fluorescence at seven pCO₂ levels (25 μatm, 50 μatm, 100 μatm, 200 μatm, 400 μatm, 800 μatm, 1 600 μatm). The results showed that, compared with 400 μatm, the growth rate and chlorophyll a content in seawater acidification (pCO₂ > 400 μatm) and alkalization (pCO₂ < 400 μatm) treatments were significantly reduced, but the degree of decrease was greater under the condition of alkalization. In addition, cells showed lower photosynthesis rates and maximum quantum yield of PSII (Fv/Fm) and relative maximum electron transport rate (rETRmax) under alkalization conditions. However, there was no significant changes in biogenic silica content and cell size among different pCO₂ levels. We found both seawater alkalization and acidification could inhibit the physiological activities of T. punctigera, and seawater alkalization had much more inhibited effects. Our results showed that the cell grown at current pCO₂ level (400 μatm) had the optical physiological performance. Moreover, among the pCO₂ levels set in this study, seawater alkalization has a more significant effect on T. punctigera. The present study provides a theoretical basis for studying the effects of changing seawater carbonate chemistry on the marine primary productivity in coastal waters.