Over the last two years, Chinese scientists from the both sides of the Taiwan Strait and from overseas, met several times to discuss the direction of deep-sea research in China. All agreed that the South China Sea should be the first priority, and a preliminary sketch of research program of the “The South China Sea Deep” was drafted. The overarching goal of the proposed program is to unveil “the life of a marginal sea”, from three major perspectives: (1) evolution of the oceanic crust in the deep basin, which will be revealed by validating the magnetic anomalies in the South China Sea using new techniques, implementing deep-water drilling of the oceanic crust, and systematically investigating the volcanic mountain chains in the basin; (2) deep-sea sedimentation, including observation of the modern deep-water currents and benthic sedimentation, and reconstruction of sediment response to the evolution of the marginal basin; and (3) biogeochemical processes to be approached by exploring the dynamics and consequences of subsurface fluid circulation, and by evaluating the microbial contribution to the deep-sea carbon cycling. Research breakthroughs are expected in the South China Sea on the basis of nation-wide cooperation with a combined effort by the scientific and engineering communities.

The Chinese probably first had the name of the South China Sea (pronounced as “Nanhai” in Chinese, where “Nan” means “south”, “hai” means “sea”) in writing at the time of Wuwang Period (1046 BC-1043 BC) during the Zhou Dynasty. “Nanhai (place name)”, was named for its closeness to the South China Sea (Nanhai), which clearly suggests that the term “Nanhai (place name)” was used later than the term “Nanhai (sea name)”. During Chengwang Period (1042 BC-1021 BC) of the Zhou Dynasty, the famous tribute of black millet (Indian millet), known as the story of “Millet of Nanhai”, was from the “Nanhai (place name)”. In Xuanwang Period (827 BC -782 BC) of the Zhou Dynasty, the name “Nanhai” used in the poem Jiang Han includes both the “Nanhai (sea name)” and “Nanhai (place name)”, which was the first time the name was used in writing. “Nanhai” was then used in Yu Gong of Shang Shu in late Zhanguo Period (475 BC -221 BC), but whether it meant the “Nanhai (sea name)” or not has yet to be confirmed. “Nanhai” was later used in Hai Nei Dong Jing of Shan Hai Jing during the Qin (221 BC -207 BC) and Han (206 BC- AD 220) Dynasties; it was also used in Nan Yue Lie Zhuan of Shi Ji and in an ancient map of early Western Han Dynasty (206 BC- AD 8), where it was definitely referring to the “Nanhai (sea name)”, just like its present meaning. From the Eastern Han Dynasty (AD 8-220) to the Tang (AD 618-907) and Song (AD 960-1279) Dynasties, the “Nanhai” was referred as the “Zhanghai”. Over the Ming (AD 1368-1644) and Qing (AD 1644-1911) Dynasties, the “Nanhai” was called the “Daminghai” and “Daqinghai” by foreigners. Then the “Nanhai” was translated as the “South China Sea” by foreigners and the name “South China Sea” has been widely used all over the world. Unfortunately, some Chinese translate the English name “South China Sea” directly into Chinese as the “Nanzhongguohai”, which is then used by some books, magazines and media. The “Nanhai” was first found and named by Chinese around 3 000 years ago, which has been well recognized all over the world. The “Nanhai” is the only name used in official publications and maps by the most recent governments of China. The “Nanhai” is also the only name used in the related administrative departments, armed forces and institutions. Therefore, the “Nanhai” should not be called the “Nanzhongguohai”. People using the name “Nanzhongguohai” can be considered ignorant to Chinese history, which may mislead people to think that the “Nanhai” (South China Sea) was first found and named by foreigners, and further confuse the Chinese sovereignty on the Nanhai.

The authors analyze the internal wave spectra of the ADCP（Acoustic Doppler Current Profiler） data from the South China Sea Monsoon EXperiment (SCSMEX) in 1998. The results suggest that the level of nonlinear interactions amongst internal waves affects the characteristics of internal wave spectra in the north South China Sea. In the seasonal thermocline (depths of 22 m and 58 m), the falloff rate of the spectra with frequency σ trends to fall between σ–1 and σ–2 for internal-wave band due to strong nonlinear interactions; furthermore, tidal harmonic frequency peaks with high energy show an amplitude decrease of σ–3 with frequency. Below the seasonal thermocline (depth 130 m), the nonlinear interactions are weakened with increasing depth so that the internal wave spectrum is similar to canonical Garrett-Munk spectrum, both showing a falloff rate of σ–2.

Using ADCP （Acoustic Doppler Current Profiler） and CTD (Conductivity/Temperature/Depth profiler) data acquired in August 2007 and the Gregg model, the authors estimate the internal-wave-scale mixing in the intermediate and deep layers of the South China Sea. They also use the Thorpe scale to study the vertical overturns in these layers and the corresponding diapycnal diffusivity. The results by the two methods are consistent, showing that the dissipation rate and diapycnal diffusivity in the upper 400m near the Luzon Strait are larger than those at 18°N, while there is no obvious distinction in the mediate and deep layers. These results, therefore, suggest that there may be active internal waves resulting in intensive internal wave mixing and vertical overturning in the upper 400m near the Luzon Strait. The dissipation rate and diapycnal diffusivity estimated by the Gregg model are at the level of 10–9 W?kg–1 and 10–6 m2?s–1, respectively. At most of the CTD stations surveyed, there always exists vertical overturning in the intermediate and deep layers and the diapycnal diffusivity estimated by the Thorpe scale does not decrease with depth. The characteristics of the fine-scale mixing reported here will facilitate the understanding of the intermediate and deep layers of the South China Sea.

In order to obtain a forecasting equation of sound velocity for seafloor sediments, the authors first apply the technology of principal component analysis and analyze existing empirical equation and its calculation errors. A principle component model is then built up using the measurement data of sediments from the continental slope and shelf in southern South China Sea. The authors also studied in theory how to exclude correlated parameters from a number of parameters that can affect the sound velocity and how to optimize a few parameters that are obviously related to sound velocity without cross-correlation. Using the optimal physical parameters, such as porosity n, median grain size Md and plastic limit Wp, a three-parameter forecasting equation of sound velocity is established for the continental shelf and slope in southern South China Sea. The equation is Cp =1774–5.0944 +12.499 Md +0.9985Wp. The relative forecasting error ranges only from –4.48% to 3.77%.

The authors analyze the essential energy loss during sediment acoustic measurement process, describe the principle of differential attenuation measurement that is the research base of parallel-axis and vertical-axis differential distance attenuation measurement methods, and deduce its attenuation coefficient formula. According to sectioning characteristics of the cylinder seafloor sediment samples from the South China Sea, a coaxial differential distance attenuation measurement method (CDDAMM) is put forward with combination of the above two methods, which is reasonable in principle and feasible in practice. Using CDDAMM, they measure the sound propagation signals of the sediments in both room and controlled temperatures, calculate the acoustic attenuation coefficient, and study the effect of temperature on sound propagation energy. The sound attenuation characters of deep-water seafloor sediments from the South China Sea are as follows. The sediments have large acoustic attenuation coefficients with high sand contents. As temperature increases, the attenuation coefficients vary nonlinearly and inhomogenously, with a descending trend on the whole. This research has provided both data and method for acoustic remote measurement and inversion of physical and mechanical properties of seafloor sediments.

Taking the precise measurement data by Hamilton’s parallel differential distance attenuation measurement method (PDDAMM) as the standard, the authors compare the Qian’s vertical coaxial attenuation measurement method (VCAMM) and Liu’s vertical differential distance attenuation measurement method (VDDAMM) with their coaxial differential distance attenuation measurement method (CDDAMM). By comparing the data from these three experiments with those by Hamilton’s method, the authors further analyze the connection of attenuation with sample length and measurement frequency as well as the benefits and drawbacks of these three experiments. Compared with VCAMM, CDDAMM is much more advisable in respect of reducing perturbations, which result from measuring instrument and the coupling between sample and transducer, and of sample length. Compared with VDDAMM, CDDAMM ensures in theory the coaxiality and directivity of compression wave in spreading process, and its data are much more precise than those by VDDAMM when using the same laboratory instrument.

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During the sporopollen and algae research of the deep-sea sediments at Core 69 in the South China Sea, five sporopollen zones have been distinguished in ascending order as Zone 1 (552.5—470 cm): Quercus (evergreen)-Pinus-Cyathea-Artemisia, Zone 2 (470—350 cm): Pinus-Podocarpus-Quercus-Polypodiaceae, Zone 3 (350—250 cm): Quercus (evergreen)-Castanopsis-Pinus-Polypodiaceae, Zone 4 (250—140cm): Pinus-Podocarpus-Artemisia-Polypodiaceae, and Zone 5 (140—0 cm): Podocarpus-Cyathea-Quercus (evergreen)-Pinus-Polypodiaceae. The sporopollen zones reflect three evolution stages of vegetation, climate and paleoenviornment in the South China Sea since 64 000 yr BP as follows: hot and wet tropical monsoon rainforest, semievergreen monsoon rainforest of northern tropics, and return to hot and wet tropical monsoon rainforest. Stage 1: During this period, the vegetation was characterized by tropical monsoon rainforest，reflecting a hot and wet climate when the sea level rose. There were many evergreen tree species. The tree layer was dominated by Dacrydium, Podocarpus, evergreen Quercus, Pinus, Elaeocarpus, Magnolia, Castanopsis, Palmae, Myrica and Altingia, among others. The herbage layer under canopy included Gramineae, Artemisia，Chenopodiaceae and Cyperaceae. The ferns were dominated by Polypodiaceae, Microlepia, Cyathea, Diplopterygium and Pteris. Mangrove plants grew along the coastal areas. Stage 2: The vegetation was semievergreen monsoon rainforest of northern tropics. This stage was indicated by the palynological Zones 2 to 4. The elements of evergreen Quercus, Castanopsis, Pinus and Magnolia from the southern subtropical zone increased in the vegetation, whereas the elements of Elaeocarpus, Dacrydium and Palmae from the tropical zone decreased. The herbage layer under canopy consisted of Gramineae, Artemisia and Cyperaceae, among others. The ferns were dominated by Polypodiaceae, Pteridium, Cyathea, Diplopterygium and Adiantum. Mangrove plants grew along the coastal areas. The vegetation was characterized by the northern tropical semievergreen monsoon rainforest, reflecting a slightly dry and warm climate when the sea level dropped. Stage 3: The vegetation was again tropical monsoon rainforest. Indicated by palynological Zone 5, the vegetation mainly consisted of Dacrydium, Podocarpus, Altingia, Palmae, Lauraceae, Magnolia, Sapindaceae, evergreen Quercus, Castanopsis and Myrica, among others. The herbage layer under canopy was dominated by Gramineae, Umbelliferae, Chenopodiaceae and Artemisia. The ferns included Polypodiaceae, Cyathea, Dicranopteris, Diplopterygium and Pteris. Mangrove plants grew along the coastal areas. All of these showed a hot and wet environment when the sea level rose. Combined the sporopollen and algae data with oxygen isotope dating, a stratigraphic division was done for the Core 69 in the South China Sea. Palynological Zone 1 corresponds to oxygen isotope period 3, and its stratigraphic time is Q33—2; Palynological Zones 2 to 4 correspond to oxygen isotope period 2, and its stratigraphic time is Q33—3; Palynological Zone 5 corresponds to oxygen isotope period 1, and its stratigraphic time is Q4.

The authors analyzed oxygen and carbon isotope of planktonic foraminifera from surface sediments and plankton tow samples collected from southern South China Sea (SCS) in spring 2002, and discussed their relationship with marine environmental parameters and depositional process. Their results show that Globigerinoides ruber and G. sacculifer have almost the same average δ18O values in the spring tow samples, which are obviously lighter than those in the surface sediments. In the surface sediments, however, the average δ18O value of G. ruber is apparently lighter than that of G. sacculifer, which may be related to gametogenesis calcification of G. sacculifer and seasonal difference of the two species. The average δ18O value of Pulleniatina obliquiloculata is apparently heavier than that of G. ruber and G. sacculifer in both the surface sediments and the upper water, suggesting a large intra-species δ18O gap between the three species. The average δ18O value of P. obliquiloculata in the upper water in spring is about 0.7‰ lighter than that in the surface sediments, possibly due to the winter flourish of P. obliquiloculata that prefers the low temperature of winter water. The average δ13C values of the three species show a similar trend in both the sediments and the upper water, namely, the heaviest for G. sacculifer, the lightest for P. obliquiloculata, and G. rubber in the middle. The difference of δ13C values between the three species may be mainly caused by vital effect. The regional variations of δ18O values of G. ruber and G. sacculifer in the surface sediments show a similar trend, with heavy values in the northwest and gradually lightening to the southeast of the studied area, all accords with the trend of yearly-averaged sea-surface temperature of gradually increasing from northwest to southeast. Both the δ18O and δ13C of P. obliquiloculata show heavier values in the upwelling stations of the studied area. The relationship of δ13C of P. obliquiloculata with nutrient level of the upper-water mass in southern SCS is contrary to that in northern SCS, which needs to be confirmed by future studies.

The authors report the organic matter in seep-carbonates from the block GC 185 (Sample GC-F) of the upper slope and the block AC 645 (Sample AC-E) of the lower slope of Gulf of Mexico, where water depth is 540 m and 2200 m, respectively. Their results show that both organic contents and alkane compositions are different between Samples AC-E and GC-F. Sample AC-E has low organic content, with relatively high fraction contents of normal alkanes, steranes and terpanes. It is dominated by low molecular weight alkanes and also with kinds of tricyclic terpanes and pentacyclic triterpanes that are maximized at 17α(H)，21β(H)-hoptane, indicating that the organic matter of the lower slope (Sample AC-E) mainly originated from bacteria and marine algae, with a little hydrocarbon seep from the underlying reservoir and slight microbial degradation. Sample GC-F has higher organic content, but its content of normal alkanes is low with mainly unresolved complex mixture (UCM). It also has kinds of tricyclic terpanes and pentacyclic triterpanes that are maximized at 17α(H)，21β(H)-nor-hoptane, suggesting that the organic matter of the upper slope (Sample GC-F) is microbial-degraded and mainly from seep hydrocarbon of the underlying reservoir. They also investigate the composition and distribution of normal alkanes, steranes and terpanes in seep carbonates, and discuss the relationship between organic matter source and cold seep.

The authors report on the mineralogical features and carbon-oxygen isotope composition of the authigenic carbonates build-up of Samples TVG-1 and TVG-11 from Jiulong methane reef in the South China Sea. The results by XRD confirm that the samples are composed of miscellaneous carbonates, including aragonite, Mg-calcite and dolomite, while detrital minerals are less abundant. In Sample TVG-1, aragonite is replaced by calcite and the pseudomorph of the former is observed, suggesting that this sample was formed earlier than the other because phase transformation of aragonite to calcite has occurred. SEM observation reveals that micro-scale acicular aragonite is usually associated with bio-filaments which may be extra-cellular polymeric substances produced by microorganisms. These observations confirm that carbonates precipitation is related to heterotrophic microbial communities fueled by hydrocarbon seepage only having weak activity currently. Stable isotope composition of the carbonates is characterized by strong 13C depletion, with a ?13C value of –46.22‰ and –52.88 ‰ for TVG-1 and TVG-11, respectively, indicating that the carbon source is most probably related to anaerobic oxidation of methane. Another distinct feature of the carbonates is its enrichment of ?18O, +3.19‰ and +4.07‰ for TVG-1 and TVG-11, respectively. 13C depletion and 18O enrichment along with the micro-fabric textural evidence suggest that the Jiulong carbonates build-up might have been precipitated from the fluids originating from gas-hydrate decomposition, which indicates that this area may have gas hydrate resources.

The authors explore the potential of gas hydrates as a source of energy. They discuss the methods for gas production from gas hydrates, which is widely available in permafrost and oceanic sediments. These hydrocarbon deposits have stimulated worldwide

efforts to understand gas production from hydrate dissociation in hydrate reservoir wells. According to formation conditions of gas hydrates, the production of gas hydrates can only be done through thermal injection, inhibitor injection, or depressurization.

In order to quantitatively assess gas production of natural gas hydrate reservoirs, a gas hydrate exploration well was used as an example to derive the gas volume produced from hydrate reservoir wells by using mathematical methods. The results show that

in gas hydrate reservoirs, the gas volume released from reservoir wells is a sensitive function of temperature and pressure of the boreholes and permeability of the gas hydrate. The function can be used to calculate gas volume produced from gas hydrate

wells and to evaluate the recoverability of gas hydrate reservoirs.

Underwater video compression is one of the key technologies for transmitting massive amount of real-time video data via underwater acoustic channels with limited bandwidth. The authors first describe the major problems involved in the development of underwater robots and underwater video compression, then comprehensively analyze the characteristics of several efficient video-coding methods, and finally discuss the future research directions. According to the characteristics of underwater imaging, they propose a potential hybrid global-local motion compensation scheme and a wavelet transform based a preprocessing method. Preparatory experimental results show that the proposed preprocessing method could effectively remove the visual and spatial redundancy of underwater images and the proposed hybrid compensation scheme could achieve a very high compression ratio. Further investigation is necessary for a fast and robust computing method of global motion.

Nowadays research device and monitoring system are power supplied by underwater lithium batteries. Underwater lithium batteries powering method has so many disadvantages that constrains the development of deep-sea scientific research. So a new mixed transmission technology based on the armored coaxial cable is proposed and finally realized. This new technology can mixed transfer direct-current high power source, real-time color image and data of both host and slave at the same time. This technology made the superposition of direct-current power source and SHDSL data signal mainly by capacitance coupling and Low-pass filtering. It adopts coaxial cable as the media for the data signal and power signal mixture transmission. Thus the goal of high-speed and long-distance transmission can be achieved.

Autonomous underwater vehicle (AUV) can be used for monitoring three-dimensional marine environment, thanks to its characters of covering large area and strong automation. The authors introduce marine monitoring technology by AUV in the world, and then present their own autonomous marine monitoring system. The system has two advantages: it can cover larger area than other AUVs and collect more autonomous data acquisition than a fixed float meter. The scheme of data acquisition, the procedure of autonomous acquisition and layered software architecture are given. The large-area field trial is first carried out in China, which shows that marine environmental three-dimensional monitoring by AUV is practical.

High strength solid buoyant material (SBM) is an important component of modern submersible technology. Hollow glass microsphere is one of the key materials for preparing SBM. In this paper, the authors first review hollow glass microsphere and SBM. Then, the research of the authors on hollow glass microsphere and SBM are also introduced. When the density of the hollow glass microsphere prepared by the group is as low as 0.21 g?cm–3, the broken particle ratio at 12 MPa of the microsphere is 40.6%. When the density of SBM is 0.52 g?cm–3, its compressive strength reaches 40 MPa.

Position and azimuth determining technology is one of the main technologies for deep ocean work. The authors propose a research method based on ring laser gyros, which can determine position and azimuth of deep-sea submersibles. According to the method, a set of analysis programs are designed, with which the attitude, velocity and position error are simulated and analyzed in detail. A 72-hour position and azimuth determining experiment has been carried out, which shows that the error of pitch and roll angle is below 0.006°, the azimuth error is below 0.035°, the velocity error is below 0.9 m?s–1, and the position error is below 29.9 km. The experiment results agree with the analysis results, which indicate that the research method is valid. Compared with position and azimuth determining system based on dynamically tuned gyroscopes, this new system has higher precision and better reliability.

Selecting an effective and convenient simplified model for dual-probe seafloor heat-flow meter is the theoretical basis for optimizing dual-probe structure, which is very important to improve heat-flow calculation accuracy. Basing on the finite element numerical model about seafloor pulsing dual-probe, the authors analyzed in detail how the dual-probe’s heat pulse duration, heat generation rate, thermal properties, length and radius affect model errors in three line source simplified models. The selected effective and convenient simplified model is the one whose model errors are the least. The results are as follows: 1) in dual-probe heat pulse method, Pulsed Finite Line Source (PFLS) model is a more practical simplified model, in which the model errors from pulse duration and probe length can be avoided; 2) in the PFLS model, model errors from probe thermal conductivity can be neglected. In addition, model errors can recede with probe spacing increasing, probe radius decreasing and probe volume heat capacity approaching the surrounding medium. When surrounding medium temperature change can be detected and recorded effectively by the sensor probe, probe heat pulse power cannot affect model errors.

A good method to find hydrothermal vents is to detect the abnormal concentration of dissolved inorganic carbon in deep ocean. The authors have designed a dissolved inorganic carbon microelectrode based on polydimethylsiloxane（PDMS）gel and Zinc-Aluminium-hydrotalcite (Zn-Al-LDH) ion carrier complex membrane, which can be used to detect deep-ocean inorganic carbon abnormality. This dissolved inorganic carbon microelectrode is miniature, and can conveniently be integrated in the same probing cavity with pH microelectrode, salinity meter, temperature sensor, oxidation-reduction potential sensor, etc. to detect various in-situ signals. It has been tested in the laboratory condition, together with Ag/AgCl reference microelectrode, connecting with the input of Keithley 6517A high-resistant potentiometer. It was shown that the signals responded well to different concentrations of NaHCO3 solutions, with 30-60 second c.a. response time and a limiting range between 10－1 and 10－4 mol?L–1.

Gas-tight sampling techniques of seafloor sediment are very important for various ocean researches, for the realizations of research goals are closely linked with the in-situ information of sediment samples. The purpose and significance to develop seafloor gas-tight sampling techniques are discussed in this paper, along with the definition of the gas-tight sampling techniques and the development of the seafloor pressure samplers. Several major techniques of the gas-tight samplers are emphatically presented. The development of the gas hydrate pressured corer in China is also introduced. Several ideas about how to develop gas-tight sampling techniques in China are put forward: 1) attach importance to the low-disturbing sampling research, and offer level clarity and material composition complete sediment samples for relevant oceanography research; 2) similar to the HYACINTH, in order to meet different geological conditions of seafloor, develop the series of gas-tight sampling devices. The gravity or shake corer can be adopt for the soft sediment (from the ooze, sand to gravel), and the rotary corer for the hard sediment; 3) carry out the core transfer technique under pressure. realize the analyzing, storing and obtaining of the small section samples without loss of pressure in laboratory, and launch geophysics, geochemistry, microorganism, and petroleum physics researches under the in-situ conditions; and 4) launch large depth sediment sampling technical research, and provide technical support for gas hydrate research in China.

A new design of 3-component magnetometer for deep ocean near seafloor is proposed to measure the geomagnetic field in high sensitivity for seafloor orebody investigation, whose magnetic field detector is based on Anisotropic Magneto Resistive (AMR) sensor. The error model of the sensor is analyzed in detail and the flow of correction procedure is given. The basic design of the sensor circuit, communication part and memory part is also discussed. Finally the experimental and test data to date is given, and the thinking of future work is discussed.

In 1994, Sino-Japan cooperative cruise for shipboard three-component magnetic field test was carried out in northern region of the South China Sea, using new Shipboard Three Component Magnetometer (STCM) developed by the Earthquake Institute of Tokyo University. About 2 500 km (6 lines) field survey data were acquired successfully. According to the magnetic boundary strike diagram (MBSD) method proposed by Seama N et al., the author analyzes these data and points out that the MBSD method can be used to express types of magnetic boundary synthetically and visibly. The author then conducts comparative analysis on the calculated result and the verified magnetic lineation of northern South China Sea basin and finds that they agree with each other very well. That study suggests that the MBSD method is useful when dealing with STCM data and studying marine magnetic structure.

Chaoshan Sag has been regarded as a prospective relic Mesozoic sedimentary sag in the South China Sea. Recent drilling confirms the existence of the Mesozoic group. In one field experiment, five sets of ocean-bottom seismometers assembled by Chinese scientists have been deployed successfully to explore the deep geological structure of the basin. The ocean-bottom seismic data show clear phases from inner crust and Moho discontinuity. The data also reveal that the crust over the Chaoshan Sag thins less compared with the neighboring areas in the northern South China Sea, and the seismic velocity of the Mesozoic formation increases considerably, which implies high consolidation of sedimentary rocks, not prone to petroleum accumulation. Such case should be avoided in future exploration of petroleum.

An ADCP mooring system was placed at a depth of 4000m southwest of the Luzon Strait in August 2008. Upper-ocean currents at high frequency were measured for about one month. Using different data processing methods, the authors analyze the current records to obtain the vertically averaged currents, tidal currents at each depth, and frequency distributions of the baroclinic currents. The main tidal components in this area are irregular diurnal tidal currents, and their ellipses are spiraling with depth. The power spectrum indicates that the tidal energy reaches the maximum near the thermocline and then decreases with depth. The analysis of the current frequency also shows that the currents have significant near-inertial oscillations. These observations provide first-hand data for studying tidal currents, near-inertial oscillations and water exchange between the South China Sea and the Pacific nearby the Luzon Strait.

Based on the monthly averaged sea surface temperature (SST) derived from the optimum interpolation sea surface temperature (OISST) from January 1982 to December 2006, the authors analyze the spatial and temporal variability of SST anomalies (SSTA) in southern South China Sea using the Empirical Orthogonal Function (EOF) method. The results show the existence of three major SSTA spatial patterns, which include the basin-scale single gyre pattern with the center in the northern area, the west-eastward antiphase dipole pattern, and the north-southward antiphase dipole pattern. The three modes all have interannual variations, which reflect the relationship between the SSTA of southern South China Sea and ENSO phenomena. The semi-annual and the intraseasonal variations are also found in Mode 3, which results from wind forcing and heat budget.

Temperature, salinity, and pressure are the three effectors of marine sediment’s physical, mechanical and acoustic properties. The authors focus on the effect of temperature perturbation on seafloor sediment, and study the spectrum Characteristics. They use the sediment remainder of the South China Sea, make artificial samples and then place them in a temperature-controlled environment, measure the sediment acoustic signals, and finally obtain the sediment’s spectrum characteristics by fast Fourier transform. The characteristics of temperature perturbation can be described by frequency drift, frequency amplitude, frequency bandwidth, and energy reception, respectively. For example, temperature contributes to the seafloor sediment’s spectrum regularity, with low repeatability; temperature increase enhances acoustic signal attenuation; frequency bandwidth and amplitude are negatively correlated, but the correlation of thermal-amplify is much clearer than thermal-bandwidth. The experiment suggests that the frequency in different temperature distinguishes the acoustics spectrum.

Characteristics of seismic facies is important for identifing submarine channels. Using 2D and 3D high-resolution seismic data, the authors are able to identify three submarine channels that developed in Pliocene, Miocene and Quaternary on the slope of the Qiongdongnan Basin. The channel that formed in Miocene mainly has such seismic characters as strong amplitude alternating with weak amplitude, reciprocal overlying, and partly developing clutter reflection. The channel that formed in Pliocene mainly has such seismic characters as high amplitude reflections, continuous or semi-continuous transversely, overlying high amplitude reflections vertically. The channel in Quaternary is characterized by classic lower cutting reflections in seismic profile, with low amplitude reflections on the whole but classic High Amplitude Reflections (HARs) at channel axis. These submarine channels should be related with the turbidity current occurring at the Lowstand System Tract (LST).

The authors have summarized a set of rules for choosing and verifying the main acquisition parameters in marine seismic exploration based on previous experiences of long-term practice. Firstly, an analysis is carried out for the selected area to establish a representative seismogeological model using various seismic and geologic information. Considering the current devices’ performances and options，they use a professional simulation software, Nucleus 6.2, to compute source parameters and to compare the response to various combinations of acquisition parameters, in order to choose a combination that is best adaptive to certain task. An actual exploration test is also carried out to verify the parameters’ combination chosen from the simulation test. Finally, the authors select the optimum Parameters’ combination and obtain quality data for production.

There have been a number of applications of satellite altimetry to seasonal and interannual sea level variability in the South China Sea. However, these applications usually exclude shallow waters along the coast, with one of the concerns being large aliased tide-correction error. In this study the authors analyzed 14 years of merged satellite altimeter data to obtain the amplitude and phase of the semi-annual cycle and to examine the variation at the K1 alias frequency (close to the semi-annual frequency). The results indicate that the amplitude of the semi-annual cycle ranges from 3-7 cm, substantial compared with that of the annual cycle; while the amplitude at the K1 alias frequency (error of the K1 tidal correction) is essentially 1 cm only. Altimeter–derived semi-annual cycle is in good agreement with that from independent tide-gauge observations, pointing to the competent ability of satellite altimetry in observing semi-annual sea level variations in the South China Sea.

Along the downwelling coast off Western Australia, late-autumn/early-winter chlorophyll a blooms are observed on the continental shelf south of Shark Bay (26°S), in contrast with summer blooms in the north. The late-autumn/early-winter blooms are in phase with seasonal strengthening of the Leeuwin Current and its eddy field. Anticyclonic eddies entrain the high phytoplankton biomass waters from the shelf and transport offshore into the oligotrophic, subtropical marine environment, as revealed by coalescing the finite-size Lyapunov exponent (FSLE) of the surface geostrophic flow field and the satellite chlorophyll a images.

The European Space Agency will launch the first salinity satellite for remotely sensing the global soil moisture and ocean salinity (SMOS) at a sun-synchronous orbit in 2009. One of the payloads on the satellite is a synthetic aperture microwave radiometer (MIRAS), which is an innovative instrument designed as a two-dimensional (2D) interferometer for acquiring brightness temperature (TB) at L-band (1.4 GHz). MIRAS allows measuring TB at a series of incidences for full polarizations. As the satellite travels, a given location within the 2D field of view is observed from different incidence angles. The authors develop a new scheme to retrieve the sea-surface salinity (SSS) from SMOS’s TB at multi-incidence angles in a pixel, utilizing the properties of emissivity changing with incidence angles. All measurements of a given Stokes parameter in a pixel are first fitted to incidence angles in three order polynomial, and then the smoothed data are used for retrieving the SSS. The procedure will remove the random noise in TB greatly. Furthermore, the new method shows that the error in retrieved SSS is very sensitive to the system biases in the calibrated TB of the sensor, but the error in the retrieval is also a system bias, which can be corrected by post-launch validation. Therefore, this method may also serve as a means to evaluate the calibration precision in TB.

To retrieve sea-surface salinity (SSS) from radiometer data at 1.4 GHz, auxiliary data of sea-surface temperature (SST), surface roughness and meteorological variables are needed. The authors study oceanic passive polarimetric microwave remote sensing using 1.4 GHz and 10.7 GHz bands. A set of algorithms are developed for 1.4 GHz and 10.7 GHz microwave polarimetric radiometer at 50° incidence angle to retrieve wind vector, as well as other geophysical parameters, such as SSS, SST, atmospheric volumes of water vapor and liquid water. Idealized retrievals are conducted using 2324 simulated brightness temperatures of full Stokes parameters at 1.4 GHz and 10.7 GHz. Results indicate that SSS, SST, sea-surface wind speed, direction, atmospheric volumes of water vapor and liquid water can be inversed at the same time. This suggests an alternative way for SSS remote sensing.

Marginal water of east Hainan Island was an area that internal waves occurred frequently, however, few studies was found and mechanism for internal waves formation was unclear. In the paper, China Brazil earth Resources Satellite data (CBERS) was used to detect and calculate distribution, direction, wavelength and amplitude of internal waves in marginal water of east Hainan Island and the mechanism of internal waves formation was also analyzed, results showed that direction of internal wave was off shoreward and wavelength was about 150-200m . The mechanism for internal wave’s formation can be postulated as by upwelling or tide tracing back.

With 42 in situ measurements of remote sensing reflectance and component absorption coefficients taken in the South China Sea and coastal waters off Fujian (China) in different seasons, the performance of the Quasi-Analytical Algorithm (QAA) and the Garver-Siegel-Maritorena (GSM) algorithm for water’s absorption coefficients are evaluated. It is found that the retrieval performance of the two algorithms is similar as those by other researchers performed in different regions. To waters in this study, QAA performed better in the South China Sea than for waters off Fujian coast. For total absorption coefficient at 443 nm (a443), the root-mean-square-error (RMSE) is 0.046 in the South China Sea, with an averaged percentage error of 7.9%, and averaged error in log scale (δ) close to 0. For coastal waters off Fujian, RMSE, an averaged percentage error and δ are 0.194, 30.6%, and -0.167, respectively. The performance of GSM is similar for the two regions of waters. For a443, RMSE and an averaged percentage error are 0.161 and 27.7% in the South China Sea, respectively; and are 0.149 and 32.1% for waters off Fujian coast. Their δ values, however, are negative (-0.142, indicating underestimation) in the South China Sea, and positive (0.016, indicating slight overestimation) in coastal waters off Fujian. Further analysis indicate that the differences between the empirical parameters employed in the algorithms and actual values of the waters under study are the main reasons causing errors in remote sensing retrievals, and it is necessary to regionally refine those parameters in order to improve the algorithm performances.wei

Although there has some been effort to retrieve suspended sediment concentration (SSC) by using remote sensing data, there are some limitations for the application of this technology in estuary waters partly due to the low spatial resolution of remote sensing data, such as the Moderate Resolution Imaging Spectroradiometer data. By comparison, the EO-1 Hyperion instrument, which is capable of resolving 196 spectral bands over the range of 400–2500 nm, with 10-nm wide band and 30-m spatial resolution, has a great potential in studying suspended sediments in estuaries. The authors study the SSC at the Zhujiang River Mouth using the Hyperion images obtained on December 4, 2006, along with the real time remote sensing reflectance. The results show that the mixing spectral decomposition model is a good choice for estimating the SSC using remote sensing data.

Using monthly products from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS), the International Satellite Cloud Climatology Project (ISCCP), and the Optimum Interpolation Sea Surface Temperature (OISST), the authors investigate the interannual variation of sea-surface temperature (SST) along a meridional transection in the South China Sea (SCS). It is found that the air-sea interaction in the tropical Pacific plays an important role in the SCS SST variation. Taking warming as an example, the SCS SST warms up in the winter of El Nino developing year and again in the following summer. The first SCS warming occurs during the mature phase of El Nino. The decrease in cloudage and increase in net shortwave radiation flux contribute to the SST warming in the winter. The air-sea interaction associated with El Nino has a direct impact on this SCS warming process. The second warming occurs in the summer after the decay of El Nino. The weakening summer monsoon reduces the latent heat flux release and coastal upwelling off the southeastern Vietnam, which could not be attributed to the direct impact of the El Nino.

In order to evaluate the ability of a high resolution Pacific-Indian basin ocean general circulation model to simulate the climatology and inteannual variability, we analyzed preliminarily the simulation results of the model in this paper, and compared them with the ocean assimilation data set and previous research works. Analyses show that the simulation results of SST distribution, structure of equatorial thermocline and zonal current, distributional pattern of equatorial current system, spatial distribution characteristics of SSH and barotropic stream function and El Nino and La Nina events are approximate to that of SODA ocean assimilation data set. Besides, the seasonal and interannaul variability of the North Equatorial Current (NEC) bifurcation agrees well with the previous study. Furthermore, our study reveal that the latitude of NEC bifurcation and Luzon Strait transport are intimately associated with ENSO cycle on the interannual timescale.

Based on the monthly mean data of Simple Ocean Data Assimilation (SODA) product, the authors analyze the seasonal salinity budget of surface layer in the southeastern Arabian Sea., The salinity variation in the region cannot be explained by surface freshwater flux. The salinity budgets in two typical regions show that horizontal advection dominates salinity variation, decreasing the salinity in winter and increasing it in summer, except for the coastal region off western India where the surface freshwater flux decreases salinity in summer. During winter, the northeast monsoon current advects fresher water from the Bay of Bengal into the Arabian Sea along the same latitude and then transports the low saline-water northward, resulting in salinity reduction in the surface layer of the southeastern Arabian Sea. During summer, southwest monsoon current advects high-salinity water in the northwestern Arabian Sea southeastward, increasing the salinity in the surface layer of the southeastern Arabian Sea. In the southeastern Arabian Sea, salinity variation of the surface layer is prominently stronger in winter than in summer.