Brillouin scattering spectrum for liquid detection and applications in oceanography

The Brillouin scattering spectrum has been used to investigate the properties of a liquid medium.Here,we propose an improved method based on the double-edge technique to obtain the Brillouin spectrum of a liquid.We calculated the transmission ratios and deduced the Brillouin shift and linewidth to construct the Brillouin spectrum by extracting the Brillouin edge signal through filtered double-edge data.We built a detection system to test the performance of this method and measured the Brillouin spectrum for distilled water at different temperatures and compared it with the theoretical prediction.The observed difference between the experimental and theoretical values for Brillouin shift and linewidth is less than 4.3 MHz and 3.2 MHz,respectively.Moreover,based on the double-edge technique,the accuracy of the extracted temperatures and salinity is approximately 0.1°C and 0.5‰,respectively,indicating significant potential for application in water detection and oceanography.

Quantitative estimation of bubble volume fraction of submarine seep plumes by modeling seismic oceanography data

Submarine seep plumes are a natural phenomenon in which different types of gases migrate through deep or shallow subsurface sediments and leak into seawater in pressure gradient.When detected using acoustic data,the leaked gases frequently exhibit a flame-like structure.We numerically modelled the relationship between the seismic response characteristic and bubble volume fraction to establish the bubble volume fraction in the submarine seep plume.Results show that our models are able to invert and predict the bubble volume fraction from field seismic oceanography data,by which synthetic seismic sections in different dominant frequencies could be numerically simulated,seismic attribute sections(e.g.,instantaneous amplitude,instantaneous frequency,and instantaneous phase)extracted,and the correlation between the seismic attributes and bubble volume fraction be quantitatively determined with functional equations.The instantaneous amplitude is positively correlated with bubble volume fraction,while the instantaneous frequency and bubble volume fraction are negatively correlated.In addition,information entropy is introduced as a proxy to quantify the relationship between the instantaneous phase and bubble volume fraction.As the bubble volume fraction increases,the information entropy of the instantaneous phase increases rapidly at the beginning,followed by a slight upward trend,and finally stabilizes.Therefore,under optimal noise conditions,the bubble volume fraction of submarine seep plumes can be inverted and predicted based on seismic response characteristics in terms of seismic attributes.

Recent improvements to the physical model of the Bohai Sea,the Yellow Sea and the East China Sea Operational Oceanography Forecasting System

In order to satisfy the increasing demand for the marine forecasting capacity,the Bohai Sea,the Yellow Sea and the East China Sea Operational Oceanography Forecasting System(BYEOFS)has been upgraded and improved to Version 2.0.Based on the Regional Ocean Modeling System(ROMS),a series of comparative experiments were conducted during the improvement process,including correcting topography,changing sea surface atmospheric forcing mode,adjusting open boundary conditions,and considering atmospheric pressure correction.(1)After the topography correction,the volume transport and meridional velocity maximum of Yellow Sea Warm Current increase obviously and the unreasonable bending of its axis around 36.1°N,123.5°E disappears.(2)After the change of sea surface forcing mode,an effective negative feedback mechanism is formed between predicted sea surface temperature(SST)by the ocean model and sea surface radiation fluxes fields.The simulation errors of SST decreased significantly,and the annual average of root-mean-square error(RMSE)decreased by about 18%.(3)The change of the eastern lateral boundary condition of baroclinic velocity from mixed Radiation-Nudging to Clamped makes the unreasonable westward current in Tsushima Strait disappear.(4)The adding of mean sea level pressure correction option which forms the mean sea level gradient from the Bohai Sea and the Yellow Sea to the western Pacific in winter and autumn is helpful to increasing the fluctuation of SLA and outflow of the Yellow Sea when the cold high air pressure system controls the Yellow Sea area.

Research on submesoscale eddy and front near the South Shetland Islands(Antarctic Peninsula)using seismic oceanography data

The submesoscale processes, including submesoscale eddies and fronts, have a strong vertical velocity, can thus make important supplements to the nutrients in the upper ocean. Using legacy multichannel seismic data AP25 of cruise EW9101 acquired northeast of the South Shetland Islands(Antarctic Peninsula) in February 1991, we identified an oceanic submesoscale eddy with the horizontal scale of ~4 km and a steep shelf break front that has variable dip angles from 5° to 10°. The submesoscale eddy is an anticyclonic eddy, which carries warm core water, can accelerate ice shelves melting. The upwelling induced by shelf break front may play an important role in transporting nutrients to the sea surface. The seismic images with very high lateral resolution may provide a new insight to understand the submesoscale and even small-scale oceanic phenomena in the interior.

China and France Plan to Launch First Joint Oceanography Satellite in 2018

The first satellite jointly developed by China and France,China-France Oceanography Satellite(CFOSAT),will be launched on a LM carrier rocket in the second half of 2018 announced at a press conference jointly held by the China National Space Administration(CNSA)and French embassy in Beijing.The satellite is being tested at a Beijingbased AIT center of CNSA.CFOSAT is an oceanic satellite supported under a joint project of CNSA and the National Center for Space Studies(CNES)of France.It will carry

Seasonal variations in wave-induced stress over global ocean based on China France Oceanography Satellite

Due to the scarcity of simultaneous observations on global-scale wind and wave spectra,there has been limited research on the characteristics of global wave-induced stress and wind stress with wave effects using observed wave spectra,particularly their seasonal variations.The China France Oceanography Satellite(CFOSAT)for the first time can simultaneously observe global sea surface wind and wave spectra,providing a solid data basis for investigating this difficult issue.In this study,the seasonal characteristics of global sea surface wave-induced stress and wind stress were analyzed by combining one-year simultaneous wind and wave observations from CFOSAT with a wave boundary layer model.Waveinduced stress was divided into wind-wave-induced stress and swell-induced stress based on different wave forms.The results showed that the wave-induced stress presented a significant inverse correlation with swell index.A higher swell index corresponded to a larger proportion of swell-induced stress,resulting in a decrease in wind stress,and vice versa,wind-wave-induced stress was dominant,resulting in an increase in wind stress.From spring to winter in the Northern Hemisphere(NH),wind-wave-induced stress predominated in the westerly belt of the Southern Hemisphere(SH),while swell-induced stress predominated near the equator.Further analysis revealed that the seasonal variation in wind-waveinduced stress in the SH was not significant,however,wind-wave-induced stress during the boreal summer was significantly lower than that in other seasons.The absolute value of swell-induced stress in the SH showed a trend of decrease and then increase from spring to winter.The percentage of increase or decrease in wind stress after considering the waveinduced stress showed a roughly symmetrical pattern between the NH and SH during the spring and autumn seasons,while the summer and winter seasons showed an asymmetrical feature.Wave-induced stress significantly modulated wind stress,resulting in zonal mean variations by up to±30%.This finding further highlights the important modulation of surface waves on wind stress at the global scale.

OCEANOGRAPHY & MARINE GEOLOGY

20030685 Chen Ping (Marine Institute, China University of Geosciences, Beijing); Fang Nianqiao Study on Changes of Gashydrate under Various Geological Processes (EarthScience-Journal of China University ofGeosciences, ISSN 1000-2383, CN 42-1233/P, 27(4), 2002, p. 441-445, 5 il-lus. , 10 refs, ) key words: gas

OCEANOGRAPHY & MARINE GEOLOGY

20032275 Di Yongjun (China University of Geosciences, Beijing); Guo Zhengfu Discussion of the Origin of Gas Hydrates (Advance in Earth Sciences, ISSN1001-8166, CN62 -1091/P, 18(1), 2003, p. 138-143, 1 illus. , 30 refs. , with English abstract) Key words: gas

OCEANOGRAPHY & MARINE GEOLOGY

20162151 Cai Qingfang(Key Laboratory of Marine Mineral Resources,Ministry of Land and Resources,Guangzhou 510075,China);Liu Dongyan Application Status of Pollen Proxies to Paleoclimate and Paleo Sea-Level Changes in Chinese Coastal Zone(Journal of Geology,ISSN1674-3636,CN32-1796/P,

OCEANOGRAPHY & MARINE GEOLOGY

20161436Cao Peng(College of Marine Geosciences,Ocean University of China,Qingdao266100,China);Shi Xuefa Rare Earth Element Geochemistry of Surface Sediments in Southeastern Andaman Sea and Implications for Provenance(Marine Geology&Quaternary Geology,ISSN0256-1492,CN37-1117/P,35(5),2015,p.57-68,9illus.,2tables。