Conference Agenda

Nearly ¾ of the world’s mega cities are by the sea and almost 80% of the global population live within 100km from the coast. These numbers make very clear that coastal regions worldwide are not only socially important but also economically critical with e.g. harbours, fish farms and exploitation sites for natural resources (oil/gas rigs or offshore wind farms). Moreover the seaside is important for recreational activities and as a natural habitat for local marine life. With respect to the extreme importance of the coastline, constant monitoring of this region is compulsory. Just like the diversity of perspectives in the coastal areas, the diversity of maritime information is complex. Many parameters and layers of information are needed to obtain a comprehensive picture for a given application.

Driven by the self-evident advantages of Earth observation methods to monitor large areas while keeping costs at a reasonable level, numerous methods have been developed and improved by the Chinese and German Dragon partners to extract maritime information from satellite-based sensors and will be outlined in the presentation. While most of the information is only available separately, the combination of different information layers is needed to generate a holistic maritime situation awareness. For this an integrated platform is needed to simultaneously visualize and generate a synopsis of different types of information, selected according to the respective application.

We present a prototype of a web-based near-real-time information platform to combine information such as sea state, wind information, AIS messages, SAR-based ship detections and sea ice information to obtain a thorough maritime situation awareness. The system can be expanded for oil spill detection and other relevant information and can thus serve as a powerful decision support system for national or international authorities e.g. in catastrophy or disaster management. The platform can help uncover exceptional conditions or behavior and represents an important constituent in sustainable coastal management.

Between 2008 and 2016, there were mass summer blooms of Enteromorpha in the Yellow Sea, China. It covered an area of thousands of square kilometers annually, lasting an average of 90 days. The blooms seriously affected the marine ecological environment and attracted considerable research attention. Remote sensing data, model predictions, and marine environment ecological data measured by ships before, during, and after the Enteromorpha blooms were used in this study of the national aquatic germ plasm resources of Qianliyan Island area. Underwater robots survey trepang, wrinkles abalone, and submarine ecological status. We found that the time taken by Enteromorpha to cover the national aquatic germ plasm resources of Qianliyan Island area was relevant, as were changes in sea surface temperature (SST). The Enteromorpha made a rise in inorganic nitrogen, reactive phosphate, and heavy metals content in upper, middle, and bottom layers of sea water, dissolved oxygen (DO) and pH were reduced; and there were changes in the dominant animal and plant population. Enteromorpha sedimentation during out-breaks was measured by benthos sampling. Considerable growth in starfish number was obtained by underwater robot observation. All of this directly influenced the regional ecological environment. Numbers of trepang and wrinkles abalone were declined over the years. Global warming and SST anomalies are the two main reasons for frequent marine disasters that take place. National aquatic germ plasm resources of Qianliyan should be protected from the blooms.

The simulation of fully nonlinear steady-state large-amplitude internal solitary waves in continuously stratified fluids based on the 2D incompressible Euler equations with Boussinesq approximation is carried out with Gerris, an open source fluid dynamics software. The large-amplitude solitary wave structure and characteristic parameters simulated by the fully nonlinear Gerris implementation of Euler model and by the weakly nonlinear KdV model are compared. The results indicate that high-order nonlinear terms should not be neglected when large-amplitude are concerned for studying internal solitary wave. The results simulated by Gerris reveal that the wavelength of isopycnic surface of a fully nonlinear large-amplitude internal solitary wave varies with depth, which makes it doubtful to retrieve the internal wave amplitude using the distance between two extreme values of internal wave pattern extracted from a spaceborne SAR image based on the analytical solution of the KdV equation. Therefore, the retrieval method is necessary to be reassessed. The validity of the interal solitary wave modeling with Gerris is tested by two sets of in-situ measurements of internal waves.

The internal solitary wave (ISW) amplitude is one of the most important parameters of ISWs. Knowing its variation is helpful for understanding ISW energy transferring, dissipating and mixing processes. Synthetic aperture radar (SAR) has been considered as a powerful instrument for deriving ISW amplitude as it can provide a wide view of ISW evolution independent from daylight, cloud coverage, and weather conditions. However, the derivation of ISW amplitude by SAR images in a two-layer shallow water system is much sensitive to the upper layer thickness. So the accurate estimation of upper layer thickness is crucial for determining the ISW amplitude. In this paper, we present a novel method of finding the best-fit values of upper layer thickness within their reasonable ranges from consecutive SAR images based on the extended Korteweg–de Vries (eKdV) equation, to derive ISW amplitude. An ISW case observed twice by the Chinese C-band SAR GaoFen-3 (GF-3) and the German X-band SAR TerraSAR-X (TS-X) with temporal interval of approximately 11 minutes, in a shallow water depth of around 74 m at the southeast of Hainan Island, is used to demonstrate the method. Compared to the representative amplitude estimation of -4.43 m - 6.99 m derived by classic KdV equation in a continuously stratified ocean, the proposed method yields an amplitude of -4.67 m, which indicates the new method can provide reliable ISW amplitude estimation. To further illustrate its practicability in the case when there were no nearly synchronous in-situ measurements with the satellite observation, the typical climatological datasets World Ocean Atlas 2013 (WOA13) are used to perform the new method in the Hainan case, and the results show the new method has prominent advantages in amplitude estimation in shallow water than the conventional method based on classic KdV theory in a continuously stratified ocean.

The HY-2B satellite is the second dynamic environment satellite in China. It was successfully launched on October 25th, 2018 with a sun-synchronous orbit at an altitude of ~970km. Repeat cycles of 14 days are planned for the first two years with oceanographic purpose and 168 days geodetic cycles will follow for the third year of the mission. The satellite is equipped with a Ku/C bands altimeter and the orbit is determined thanks to SLR, GPS.

The HY-2B satellite altimeter provides sea surface height, significant wave height, sea surface wind speed, and polar ice sheet elevation. First of all, the description of instruments and the instrument parameters will be put forward briefly in this research. And then, the current status of the HY-2B products will be described in detail, including the measurement accuracy.

Comparing with Jason-2 and Jason-3 satellite radar altimeters and on-site buoys, the objects of comparison include significant wave height, sea surface wind speed, and sea level anomaly and so on. It is found that the precision of HY-2B satellite radar altimeter secondary products reaches the same kind of satellite radar altimeter products in the world, and some products are better than Jason-2 and Jason-3 standard products.