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An upper ocean response to Typhoon Bolaven analyzed with Argo profiling floats

Acta Oceanologica Sinica 2014年第11期33卷 90-101页

作者： LIU Zenghong XU Jianping SUN Chaohui WU Xiaofen state Key Laboratory Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic Administration Second Institute of Oceanography State Oceanic Administration

In situ observations from Argo profiling floats combined with satellite retrieved SST and rain rate are used to investigate an upper ocean response to Typhoon Bolaven from 20 through 29 August 2012. After the passage of Typhoon Bolaven, the deepening of mixed layer depth（MLD）, and the cooling of mixed layer temperature（MLT） were observed. The changes in mixed layer salinity（MLS） showed an equivalent number of increasing and decreasing because the typhoon-induced salinity changes in the mixed layer were influenced by precipitation, evaporation, turbulent mixing and upwelling of thermocline water. The deepening of the MLD and the cooling of the MLT indicated a significant rightward bias, whereas the MLS was freshened to the left side of the typhoon track and increased on the other side. Intensive temperature and salinity profiles observed by Iridium floats make it possible to view response processes in the upper ocean after the passage of a typhoon. The cooling in the near-surface and the warming in the subsurface were observed by two Iridium floats located to the left side of the cyclonic track during the development stage of the storm, beyond the radius of maximum winds relative to the typhoon center. Water salinity increases at the base of the mixed layer and the top of the thermocline were the most obvious change observed by those two floats. On the right side of the track and near the typhoon center when the typhoon was intensified, the significant cooling from sea surface to a depth of 200×10^4 Pa, with the exception of the water at the top of the thermocline, was observed by the other Iridium float. Owing to the enhanced upwelling near the typhoon center, the water salinity in the near-surface increased noticeably. The heat pumping from the mixed layer into the thermocline induced by downwelling and the upwelling induced by the positive wind stress curl are the main causes for the different temperature and salinity variations on the different sides of the track

关键词： Typhoon Bolaven Argo profiling floats upper ocean response ocean heat content

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Grain size composition and transport of sedimentary organic carbon in the Changjiang River(Yangtze River) Estuary and Hangzhou Bay and their adjacent waters

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Acta Oceanologica Sinica 2015年第10期34卷 46-56页

作者： ZHANG Weiyan JIN Haiyan YAO Xuying JI Zhongqiang ZHANG Xiaoyu YU Xiaoguo ZHANG Fuyuan GAO Aigen Key Laboratory of Submarine Geosciences State Oceanic Administration Second Institute of Oceanography State Oceanic Administration Key Laboratory of Marine Ecosystem and Biogeochemistry State Oceanic Administration Department of Earth Sciences Zhejiang University

Surface sediments from the Changjiang River （Yangtze River） Estuary, Hangzhou Bay, and their adjacent waters were analyzed for their grain size distribution, organic carbon （OC） concentration, and stable carbon isotope composition （δ13C）. Based on this analysis, about 36 surface sediment samples were selected from various environments and separated into sand （〉0.250 ram, 0.125-0.250 ram, 0.063-0.125 mm） and silt （0.025-0.063 mm） fractions by wet-sieving fractionation methods, and further into silt- （0.004-0.025 mm） and clay-sized （〈0.004 mm） fractions by centrifugal fractionation. Sediments of six grain size categories were analyzed for their OC and 613C contents to explore the grain size composition and transport paths of sedimentary OC in the study area. From fine to coarse fractions, the OC content was 1.18%, 0.51%, 0.46%, 0.42%, 0.99%, and 0.48%, respectively, while the δ13C was -21.64‰, -22.03‰, -22.52‰, -22.46‰, -22.36‰, and -22.28%0, respectively. In each size category, the OC contribution was 42.96%, 26.06%, 9.82%, 5.75%, 7.09%, and 8.33%, respectively. The OC content in clay and fine silt fractions （〈0.025 ram） was about 69.02%. High OC concentrations were mainly found in offshore modern sediments in the northeast of the Changjiang River Estuary, in modern sediments in the lower estuary of the Changjiang River and Hangzhou Bay, and in Cyclonic Eddy modern sediments to the southwest of the Cheju Island. Integrating the distribution of terrestrial OC content of each grain size category with the δ13C of the bulk sediment indicated that the terrestrial organic material in the Changjiang River Estuary was transported seaward and dispersed to the Cyclonic Eddy modern sediments to the southwest of the Cheju Island via two pathways： one was a result of the Changjiang River Diluted Water （CDW） northeastward extending branch driven by the North Jiangsu Coastal Current and the Yellow Sea Coastal Current, while the other one was the result of the CDW southward extendin

关键词： Changjiang River (Yangtze River) Estuary Hangzhou Bay grain size composition organic carbon,material transport

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Equilibrator-based measurements of dissolved methane in the surface ocean using an integrated cavity output laser absorption spectrometer

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Acta Oceanologica Sinica 2015年第6期34卷 34-41页

作者： LI Yuhong ZHAN Liyang ZHANG Jiexia CHEN Liqi Key Laboratory of Global Change and Marine-Atmospheric Chemistry State Oceanic Administration Third Institute of Oceanography State Oceanic Administration

A new off-axis integrated cavity output spectroscopy （ICOS） is coupled to Weiss equilibrator for continuous high- resolution dissolved methane measurement in the surface ocean. The time constant for the equilibrator in freshwater at room temperature is determined via dis-equilibration and re-equilibration experiments. The constant for methane is about 40 min. The system is calibrated using a standard gas of 3.980×10-6, and the precision of the ICOS for methane is 0.07%. This system is equipped onboard to measure the spatial distribution in methane concentrations of South Yellow Sea （SYS） along the cruise track from Shanghai to Qingdao. Result shows that the methane concentration varies from 2.79 to 36.36 nmol/L, reveals a significant pattern of methane source in SYS, and a distinct decreasing trend from south to north. The peak value occurs at the coast area outside mouth of the Changjiang River, likely to be affected by the Changjiang diluted water mass dissolving a large amount of rich in methane. Moreover, all the surface waters are oversaturated, air-to-sea fluxes range from 98.59 to 5 485.35 μmol/（m2·d）（average value （1 169.74±1 398.46） μmol/（m2·d））, indicating a source region for methane to the atmosphere. Key words： methane, equilibrator, off-axis integrated cavity output spectroscopy （ICOS）, South Yellow Sea

关键词： methane equilibrator off-axis integrated cavity output spectroscopy (ICOS) South Yellow Sea

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Morphological Characteristics of Sand Waves in the Middle Taiwan Shoal Based on Multi-beam Data Analysis

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Acta Geologica Sinica(English Edition) 2014年第5期88卷 1499-1512页

作者： BAO Jingjing CAI Feng REN Jianye ZHENG Yongling WU Chengqiang LU Huiquan XU Yan China University of Geosciences (Wuhan) Third Institute of Oceanography State Ocean Administration Island Research Centre State Ocean Administration

A DTM map of the study area in the Taiwan Shoal was drawn based on precise and high- density data acquired in a field survey by a multi-beam sounding system （R2Sonic2024）. We identified sand waves in the study area at water depths of 13.89-49.12 m; the main sand waves had heights of 5- 25 m, lengths of 0.1-2.0 km, and crest lines 0.1-6.5 km long. The spatial distribution of the sand waves on the seabed is dense in the north and sparse in the south and the directions range between 50°-80° and 90°-135°. Between the main sand waves, secondary sand waves develop with heights of 0.1-5.0 m and lengths of 10-100 m, which are difficult to detect by satellite remote sensing. By comparing the evolution structures of the secondary and main sand waves, we identified three evolution modes of the secondary sand waves： parallel, oblique, and divergent modes according to the relative crest directions. Suitable water depth, reciprocating current speeds between 40 and 100 cm/s, and abundant sediment supply create favorable conditions for the formation of linear sand waves. Comparing the DTM maps and profiles of the June 2012 and June 2013 surveys of the same area, we found that the shape and morphology of the sand waves remained mostly unchanged under normal hydrodynamic conditions.

关键词： secondary sand wave main sand wave stability morphology Taiwan Shoal

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Effects of Tamarisk shrub on physicochemical properties of soil in coastal wetland of the Bohai Sea

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Acta Oceanologica Sinica 2016年第5期35卷 106-112页

作者： HE Xiuping WANG Baodong XIE Linping XIN Ming WANG Wei WANG Zicheng ZHANG Wenquan WEI Qinsheng First Institute of Oceanography State Oceanic Administration

There are many different and even controversial results concerning the effects of Tamarisk on the physicochemical properties of soil. A year-round monitoring of soil salinity, p H and moisture is conducted beneath the Tamarisk shrub in a coastal wetland in the Bohai Sea in China, to ascertain the effects of Tamarisk on the physicochemical properties of soil in coastal wetland. Compared with the control area, the soil moisture content is lower around the area of the taproot when there is less precipitation in the growing season because of water consumption by Tamarisk shrub. However, the soil moisture content is higher around the taproot when there is more precipitation in the growing season or in the non-growing period because of water conservation by the rhizosphere. The absorption of salt by the Tamarisk shrub reduces the soil salinity temporarily, but eventually salt returns to the soil by the leaching of salt on leaves by rainfall or by fallen leaves. The annual average soil moisture content beneath the Tamarisk shrub is lower than the control area by only 6.4%, indicating that the Tamarisk shrub has little effect on drought or water conservation in soils in the temperate coastal wetland with moderate annual precipitation. The annual average salinity beneath the Tamarisk shrub is 18% greater than that of the control area, indicating that Tamarisk does have an effect of rising soil salinity around Tamarisk shrubs. The soil p H value is as low as 7.3 in summer and as high as 10.2 in winter. The p H of soil near the taproot of the Tamarisk shrubs is one p H unit lower than that in the control area during the growing season. The difference in p H is less different from the control area in the non-growing season, indicating that the Tamarisk shrub does have the effect of reducing the alkalinity of soil in coastal wetland.

关键词： coastal wetland Tamarisk soil physicochemical parameter

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Analysis of multi-dimensional SAR for determining the thickness of thin sea ice in the Bohai Sea

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Chinese Journal of Oceanology and Limnology 2013年第3期31卷 681-698页

作者：张晰张杰孟俊敏苏腾飞 The First Institute of Oceanography State Oceanic Administration

Flat thin ice (<30 cm thick) is a common ice type in the Bohai Sea, China. Ice thickness detection is important to offshore exploration and marine transport in winter. Synthetic aperture radar (SAR) can be used to acquire sea ice data in all weather conditions, and it is a useful tool for monitoring sea ice conditions. In this paper, we combine a multi-layered sea ice electromagnetic (EM) scattering model with a sea ice thermodynamic model to assess the determination of the thickness of flat thin ice in the Bohai Sea using SAR at different frequencies, polarization, and incidence angles. Our modeling studies suggest that co-polarization backscattering coefficients and the co-polarized ratio can be used to retrieve the thickness of flat thin ice from C- and X-band SAR, while the co-polarized correlation coefficient can be used to retrieve flat thin ice thickness from L-, C-, and X-band SAR. Importantly, small or moderate incidence angles should be chosen to avoid the effect of speckle noise.

关键词： multi-dimensional SAR sea ice in the Bohai Sea flat thin ice thickness retrieval

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Paleoenvironmental Evolution of the Beilun River Estuary,Northwest South China Sea,During the Past 20,000 Years Based on Diatoms

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Acta Geologica Sinica(English Edition) 2016年第6期90卷 2244-2257页

作者： CHEN Min QI Hongshuai LAN Dongzhao LAN Binbin FANG Qi Third Institute of Oceanography State Oceanic Administration

The paleoenvironmental history of the Beilun River estuary on the coast of Beibu Gulf in the northwest South China Sea is reconstructed based on fossil diatoms, isotopic dating, sedimentary grain size data, mineralogy and geochemistry in three sediment core samples. Results show that the estuary has experienced significant environmental changes since deposition began about 20,000 yr ago. Freshwater runoff of the Beilun River initially was strong. However, the freshwater runoff reduced significantly after a transgressive event. Subsequently the estuary’s position began to migrate to the northeast. At the end of the Late Pleistocene the estuary shifted gradually towards the southwest. In the Early-Mid Holocene, the estuary’s geomorphology was shaped by seawater transgressing into the ancient river channel. The basin was filled continuously but slowly to form the present Beilun River estuary. Holocene transgression in this area could be divided roughly into three stages, including oscillation period 1, the maximum transgression period, and oscillation period 2.

关键词： diatoms Beilun River estuary paleoenvironment Quaternary

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Sea surface temperature anomalies in the South China Sea during mature phase of ENSO

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Chinese Journal of Oceanology and Limnology 2016年第3期34卷 577-584页

作者：丘福文潘爱军张善武查晶孙豪为 Third Institute of Oceanography State Oceanic Administration

Based on the 18-year （1993-2010） National Centers for Environmental Prediction optimum interpolation sea surface temperature （SST） and simple ocean data assimilation datasets, this study investigated the patterns of the SST anomalies （SSTAs） that occurred in the South China Sea （SCS） during the mature phase of the E1 Nifio/Southem Oscillation. The most dominant characteristic was that of the out- of-phase variation between southwestern and northeastern parts of the SCS, which was influenced primarily by the net surface heat flux and by horizontal thermal advection. The negative SSTA in the northeastern SCS was caused mainly by the loss of heat to the atmosphere and because of the cold-water advection from the western Pacific through the Luzon Strait during E1 Nifio episodes. Conversely, it was found that the anomalous large-scale atmospheric circulation and weakened western boundary current during E1 Nifio episodes led to the development of the positive SSTA in the southwestern SCS.

关键词： sea surface temperature (SST) anomalies E1 Nifio/Southern Oscillation (ENSO) South China Sea (SCS)

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The winter western boundary current of the South China Sea:physical structure and volume transport in December 1998

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Acta Oceanologica Sinica 2018年第3期37卷 1-7页

作者： LI Li GUO Xiaogang WU Risheng Third Institute of Oceanography State Oceanic Administration

The unique survey in December 1998 mapped the entire western boundary area of the South China Sea（SCS）,which reveals the three-dimensional structure and huge volume transport of the swift and narrow winter western boundary current of the SCS（SCSwwbc） in full scale. The current is found to flow all the way from the shelf edge off Hong Kong to the Sunda Shelf with a width around 100 km and a vertical scale of about 400 m. It appears to be the strongest off the Indo-China Peninsula, where its volume transport reached over 20×10~6 m^3/s. The current is weaker upstream in the northern SCS to the west of Hong Kong. A Kuroshio loop or detached eddy intruded through the Luzon Strait is observed farther east where the SCSwwbc no more exists. The results suggest that during the survey the SCSwwbc was fed primarily by the interior recirculation of the SCS rather than by the＂branching＂ of the Kuroshio from the Luzon Strait as indicated by surface drifters, which is likely a near-surface phenomenon and only contributes a minor part to the total transport of the SCSwwbc. Several topics related to the SCSwwbc are also discussed.

关键词： South China Sea western boundary current winter hydrographic structure volume transport

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2-ORDER TURBULENCE CLOSURE PLANKTON ECOSYSTEM DYNAMICS MODEL AND ITS APPLICATION

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Journal of Hydrodynamics 2001年第3期13卷 17-23页

作者： Wan, Zhen-Wen Yuan, Ye-Li Qiao, Fang-Li state Oceanic administration Qingdao 266003 China

The basic concepts of continuous neurogen dynamics, particle and continuous mass, were cited to describe plankton ecosystems, so a continuous neurogen dynamics model of plankton ecosystem was developed by logically reasoning with less ecological experiential relation. For precise parameterization of diffusion acted on plankton by hydrodynamics, the scheme of 2-order turbulence closure of geophysical fluid dynamics was generalized to enclose the equations of plankon ecosystem dynamics model. This model was applied to simulate a natural ecological process in Jiaozhou Bay. Comparison between simulation and data showed the exciting prognosis ability of this model.

关键词： Ecosystems Mathematical operators Numerical analysis Simulation Turbulence

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