The modified method of reanalysis wind data in estuarine areas

High-quality wind field data are key to improving the accuracy of storm surge simulations in coastal and estuarine water. These data are also of great significance in studying the dynamic processes in coastal areas and safeguarding human engineering structures. A directional correction method for ECMWF reanalysis wind data was proposed in this paper based on the correlation with the measured wind speed and direction. The results show that the accuracies of wind speed and direction were improved after being modified by the correction method proposed in this paper. The modified wind data were applied to drive the storm surge model of the Yangtze Estuary for typhoon events, which resulted in a significant improvement to the accuracy of hindcasted water levels. The error of the hindcasted highest water levels was reduced by 16–19 cm

Numerical Study on Spatio-Temporal Distribution of Cold Front-Induced Waves along the Southeastern Coast of China

Cold fronts, as one of the most frequent extreme weather events, can induce significant waves on the sea. This work analyzes the spatial and temporal variations in cold front events, especially the characteristics of wind directions during cold fronts in the East China Sea (ECS). The SWAN (Simulating Waves Nearshore) model is applied to simulating the waves induced by cold fronts. To calibrate the model, two typical cold front events were selected to simulate the corresponding waves in the ECS. The results indicate that the data misfit between the observed and modeled significant wave heights (SWH) is within a reasonable range. Idealized sensitivity experiments were then designed in order to analyze and discuss the responses of ocean waves to wind direction, swell distribution, maximum of significant wave heights (MSWH), and time lag during the cold fronts. The results show that the average MSWH in the ECS decreases monotonically with the deflection of wind direction from north-east to north-west, while specific nearshore sites do not conform to this pattern due to topography. The time series of SWH indicate that the action of the swells leads to a prolongation of the duration of catastrophic waves. This work investigates the temporal and spatial distribution characteristics of cold front-induced wind wave fields in offshore Zhejiang, which has important value for the study of the impact of cold fronts on the ocean as well as disaster prevention and mitigation efforts

The Early Warning of Wave Disaster Risk in Deep-water Cage Culture: A case study of Nanji Island

By analyzing the damage mechanism of the cage, the paper classified the damage level and risk early warning level of the deep-water cage according to the three damage forms of deformation and fracture of the floating frame, broken anchor rope and off anchor, and excessive volume loss of the cage. For the six cage farming enterprises in Nanji Island, the damage levels of cages under different scenarios were calculated, the quantitative database was established, the input items of risk early warning system were simplified, the wave height threshold corresponding to the risk early warning levels was analyzed and determined, and the refined storm surge nearshore wave coupling numerical prediction model was used to make cage disaster risk early warning products, which were verified by typhoon 1808 "Maria" and typhoon 1909 "Lekima" . The predicted results were consistent with the actual damage, which could provide technical support and services for local cage aquaculture enterprises to deal with wave disasters in the future

Ocean acidification increases cadmium accumulation in marine bivalves: a potential threat to seafood safety

To date, the effects of ocean acidification on toxic metals accumulation and the underlying molecular mechanism remains unknown in marine bivalve species. In the present study, the effects of the realistic future ocean pCO2 levels on the cadmium (Cd) accumulation in the gills, mantle and adductor muscles of three bivalve species, Mytilus edulis, Tegillarca granosa, and Meretrix meretrix, were investigated. The results obtained suggested that all species tested accumulated significantly higher Cd (p<0.05) in the CO2 acidified seawater during the 30 days experiment and the health risk of Cd (based on the estimated target hazard quotients, THQ) via consumption of M. meretrix at pH 7.8 and 7.4 significantly increased 1.21 and 1.32 times respectively, suggesting a potential threat to seafood safety. The ocean acidification-induced increase in Cd accumulation may have occurred due to (i) the ocean acidification increased the concentration of Cd and the Cd2+/Ca2+ in the seawater, which in turn increased the Cd influx through Ca channel; (ii) the acidified seawater may have brought about epithelia damage, resulting in easier Cd penetration; and (iii) ocean acidification hampered Cd exclusion