Contrast validation test for retrieval method of high frequency ground wave radar

In this paper, on the basis of the working principles of high frequency ground wave radar for retrieval of ocean wave and sea wind elements were used to systematically study the data obtained from contrast validation test in Zhoushan sea area of Zhejiang Province on Oct. 2000, to validate the accuracy of OSMAR2000 for wave and wind parameters, and to analyze the possible error caused when using OSMAR2000 to retrieve ocean parameters.

SEASONAL VARIATIONS OF CIRCULATION AND SUSPENDED MATTER TRANSPORT IN THE YELLOW AND EAST CHINA SEAS

The Princeton Ocean Model (POM) was modified and used to study the monthly mean circulation in the Yellow Sea and the East China Sea. The calculated results showed almost all major characteristics of the circulation system and their seasonal evolutions. Offshore branch and inshore branch of the Taiwan Warm Current derived from the two sides of the Taiwan Island vary significantly in different seasons. The Tsushima Warm Current is a multi-source current, and especially in winter, mid-shelf water is its main source. The Yellow Sea Warm Current (YSWC) is the strongest in winter, and a part of the YSWC water always adds into the Tushima Warm Current through the north and south sides of the Cheju Island. The calculated thermal structures showed distinct path of the YSWC in winter and the position and scope of the Yellow Sea Cold Water Mass in summer. Based on the circulation simulation, suspended matter transport was modeled numerically by adding its governing equation into the POM. Simulated results on the temporal and spatial distribution of total suspended matter concentration revealed and further proved that seasonal characteristics of suspended matter transport are: storage in summer and autumn, transport in winter and spring in the Yellow and East China Seas. Shelf circulation plays a crucial role in long-term suspended matter transport.

REEXAMINATION OF THE ROLE OF VERTICAL CIRCULATION IN SEDIMENTATION IN THE YELLOW AND EAST CHINA SEAS

Based on figures available, role of upwelling in some fine sediment patches on China Sea shelves is examined from the viewpoints of physical process and biological process, respectively. It is further verified with more data wherever upwelling exists on continental shelf mud must occur-coincidence of upwelling areas with mud patches. Marine rain is named for physical process and marine snow is used as usual. It is pointed out that marine rain and marine snow are usually coexistent and interact each other. It is concluded that the mud patch southeast of Cheju Is. is formed by marine rain rather than marine snow since terrigenous elements are high and biogenic elements are not and that judging from sediment trap data the mud in the Okinawa Trough is accumulated by horizontal transport via wind-driven transverse circulation from inner shelf in winter and by vertical flux through biological activities (marine snow) and Aeolian deposit in spring. A number of controversies on fine sediment issues on China Sea shelves need to be further deliberated. Interaction between marine rain and snow also needs to be experimentally and theoretically studied.

DYNAMICS OF THE KUROSHIO INTRUSION INTO THE SOUTHEAST CHINA ADJACENT WATERS-A NUMERICAL STUDY

A series of numerical experiments have been carried out to study the dynamics of the Kuroshio intrusion into the north South China Sea (SCS) and the East China Sea (ECS). The Kuroshio itself can intrude into the SCS through the middle Luzon Strait, and into the ECS northeast to Taiwan and west of Tokara Strait. An inshore current from the north SCS through Taiwan Strait, shelf region of the ECS and to the Korea Strait is induced. The numerical experiments show that the momentum advection plays a substantial role in generating the NW Luzon Cyclonic Gyre (NWLCG) and has great influence on the pathway of the SCS Branch of the Kuroshio. The NWLCG is thus partly of inertial recirculation recirculation. Topography is a key factor for the formation of the circulation in the study area. The beta effect and momentum advention may intensify the Kuroshio intrusion northeast of Taiwan to a certain degree, but not large.

POTENTIAL APPLICATION FOREGROUND OF OCEAN MODE IN NAVY OCEANOGRAPHY

Ocean mode (or quasigeostrophic wave) analysis is one of the key data processing technique in oceanic acoustic tomography experiment. A primary study on its application foreground in Navy Oceanography is put forward with CTD data and Carton oceanic assimilation data. It shows that the sound speed mode is not well orthogonal to each other, so that it is practically no use. However, the current mode calculated from the CTD data collected in summer as the position with weak stochastic processes and strong geostrophic balance is well orthogonal to each other, it can be used everywhere in the ocean of the similar water mass at any time as long as the basic condition serves. It can be used for decomposition and reconstruction of dynamic or quasi-dynamic factors such as seawater temperature, from which and average of salinity the sound speed profile can be composed. It also shows that the monthly James Carton assimilation data is well consistent with observation ones in subsurface layer in the region with weak current speed but not well below subsurface layer or near the Kuroshio in the western Pacific. By running a nested ocean general circulation model with adjusted vertical eddy diffusivity to do data assimilation again and applying current mode analysis to reconstruct or compose related factors, it is hopefully possible to improve the precision and space resolution of the oceanic assimilation data. So that, it is definitely possible to obtain the three dimensional high resolution distribution of ocean sound speed in real time with the satellite SST and surface wind fields only.

SIMULATION OF EDDIES AFFECTED BY TOPOGRAPHY IN A BAROTROPICAL QUASI-GEOSTROPHIC FLUID

Based upon the quasi-geostrophic barotropic equation, taking the effect of seabed topography into account, analytical solutions and simulated eddies associated with different topographies are obtained. Through exhibiting the shape of various eddies we have found some interesting phenomena and had a better understanding of the importance of seabed topography to the eddy shape.

SEASONAL CIRCULATION IN THE NORTHWESTERN TROPICAL PACIFIC OCEAN DIAGNOSED WITH THE ASSIMILATION DATA FROM 1989 THROUGH 1997

An assimilation data set based on the Geophysical Fluid Dynamics Laboratory (GFDL) Modular Ocean Model version 3 (MOM3) and the NODC XBT data set is used to examine the circulation and its variabilities in the western tropical Pacific, with special emphasis on the seasonal variations. It is shown that the assimilated and observed mean velocities and transports of the major flows in the western tropical Pacific agree well. The flows in the north Pacific, including the North Equatorial Current (NEC), Kuroshio, Mindanao Current (MC) and north Equatorial Countercurrent (NECC) west of 140°E display the seasonal cycles almost in the same phase, with the biggest transport in spring and the smallest in autumn. The phase of the NECC seasonal cycle east of 140°E is opposite to that in the west. Besides of the annual cycle, there seems to be a semi-annual fluctuation of the NECC transport possibly resulting from the phase lag between seasonal cycles of the NEC and NGCC. Strong in summer during the southeast monsoon, the seasonal cycle of the Indonesian Throughflow (ITF) is closely linked with those of both the MC and the New Guinea Coastal Current/Undercurrent (NGCC/NGCUC), but not as strong as that in observations probably caused by the superimposed seasonal and interannual variations. Variations on the interannual time scale are also discussed, but only indistinct interannual variations of the flows related to the ENSO are revealed during 1989-1997. Transport of the NEC, Kuroshio and NECC are slightly larger in the E1 Nino years when that of the ITF is weaker, while the MC has little ENSO-related variation. There were also quasi-biennial signals superimposing the ENSO-like oscillations in the flows, but their relationships with the ENSO are still unclear.