How to identify internal solitary wave by using temperature logger?5 answersInternal solitary waves (ISWs) can be identified using temperature loggers through various methods. The traditional approaches include the whole water column isotherm (WCI) method and the single isotherm (SI) method, with the novel temperature superposition (TS) method showing promising results. In situ observations of ISWs are crucial for enhancing nonlinear internal wave theories, but challenges arise due to the complex thermohaline data collected by underwater gliders. Glider data analysis, including estimating vertical water velocity and identifying wave packets, provides a basis for ISW observation using gliders. Additionally, ocean buoys equipped with systems like acoustic Doppler current meters can monitor ISWs in real-time, benefiting offshore activities like oil and gas development in the South China Sea. These methods collectively contribute to a comprehensive approach for effectively identifying and monitoring ISWs using temperature loggers and oceanographic instruments.
How wave influence coastal flooding?5 answersWaves play a crucial role in influencing coastal flooding by causing wave overtopping, which can lead to significant inundation of coastal areas. The stochastic nature of waves also contributes to flood uncertainty, especially on short timescales, comparable to sea-level rise scenarios. Studies show that wave-induced processes, along with wind, tides, and baroclinicity, impact sea levels during extreme storm events, with wave-dependent stress and mixing affecting sea level variability significantly. Additionally, the characteristics of coral reefs can alter the effects of wave-driven flooding, with projections indicating that rising sea levels and climate change may reduce the reefs' ability to mitigate coastal hazards in the future. Overall, understanding wave dynamics is essential for predicting and managing coastal flooding risks effectively.
What are the coastal mapping techniques?5 answersCoastal mapping techniques include the use of nautical charts, hyperspectral imagery, remote sensing, video processing, and satellite earth observation data. Nautical charts are used to ensure the safety of shipping activities and contain information such as seabed topography, navigation hazards, and human-made structures. Hyperspectral imagery combined with LiDAR-based DEMs can be used to extract shorelines with sub-pixel accuracy and improve positional accuracy. Video processing algorithms, such as dynamic mode decomposition (DMD), can be used to map coastal bathymetry, wave directions, celerity, and near-surface currents from aerial video footage. Pixel-based techniques using a combination of multispectral and Synthetic Aperture Radar data can provide landcover classification for coastal areas, improving accuracy compared to traditional methods. Advanced technologies like the Coastal Zone Mapping and Imaging Lidar system (CZMIL) integrate lasers, receivers, scanners, and imagers to improve coastal mapping performance and produce value-added information products.
What are the main sources of coastal ocean waste?3 answersThe main sources of coastal ocean waste include industrial and domestic effluents, ballast water and brine wastes, accidental oil spills, modification of coastal structures, and discharge of treated wastewater and ballast water. Ocean waste can also result from poor handling of cargo on ships and vessels, as well as waste that enters waterways and rivers and flows into the sea. Waste is transported to the marine environment through various pathways, including river discharge, atmospheric deposition, direct discharge of emissions, solid wastes, radioactivity, thermal energy, and noise. Other sources of coastal ocean waste include sewage outfalls, storm runoff from agricultural lands and metropolitan areas, waste sludges, dredge materials, and low-level discharges into the coastal zone. Coastal pollution is also caused by nutrient-induced eutrophication, heavy metal pollution, organic pollutants such as oil and plastics, and radionuclide pollution.
How does the internal wave activity affect the ecosystem in northern South China Sea?5 answersInternal wave activity in the northern South China Sea (NSCS) has significant impacts on the ecosystem. These waves enhance biological productivity and affect coral reefs by modulating nutrient concentrations and temperature. The waves can suspend seafloor sediments and form marine nepheloid layers, which affect sediment and pollutant transport. The NSCS is home to the largest internal waves in the world's oceans, with some waves reaching heights of over 200 meters. These waves generate extreme turbulence, with turbulence levels over 10,000 times higher than in the open ocean. The waves are influenced by the Kuroshio current, which refracts the internal wave field. The increased internal wave activity in the NSCS is driven by intrusions of the Kuroshio Current into the Luzon Strait and freshwater fluxes associated with the El Nino-Southern Oscillation. Overall, the internal wave activity in the NSCS plays a crucial role in shaping the ecosystem and has implications for mitigating climate change impacts on coastal ecosystems.
What are the benefits of a holistic approach to coastal governance?5 answersA holistic approach to coastal governance offers several benefits. Firstly, it allows for the management of coastal and marine ecosystems in a more integrated and coordinated manner, leading to more sustainable outcomes. Secondly, it helps address deep-rooted issues such as path dependency, institutional inertia, and policy layering, which are barriers to transformative marine governance. Thirdly, it enables the identification and substantiation of significant physical geographical factors that impact the sustainability of coastal resorts, leading to better planning and development of beaches, protection from erosion, and maintenance of beach infrastructure. Fourthly, it provides a framework and methodology to assess local coastal governance, which can help local governments in managing climate risks and coastal assets more effectively. Lastly, a holistic approach facilitates community-based decision-making and prioritization of actions for climate risk governance, leading to better adaptation and mitigation against climate adversities.