Geosynchronous Satellite GF-4 Observations of Chlorophyll-a Distribution Details in the Bohai Sea, China

We analyzed the distribution of chlorophyll-a (Chla) in the Bohai Sea area based on data from the geosynchronous orbit optical satellite Gaofen-4 (GF-4), which was launched in 2015, carrying a panchromatic multispectral sensor (PMS). This is the first time the geosynchronous orbit optical satellite GF-4 remote-sensing data has been used in China to detect the Chla change details in the Bohai Sea. A new GF-4 retrieved model was established based on the relationship between in situ Chla value and the reflectance combination of 2 and 4 bands, with the R2 of 0.9685 and the total average relative error of 37.42%. Twenty PMS images obtained from 2017 to 2019 were applied to analyze Chla in Bohai sea. The results show that: (1) the new built Chla inversion model PMS-1 for the GF-4 PMS sensor can extract Chla distribution details in the Bohai Sea well. The high Chla content in the Bohai Sea is mainly located in coastal areas, such as the top of Laizhou Bay, Bohai Bay and Liaodong Bay, with the value being around 13 µg/L. The concentration of Chla in the Bohai Strait and northern Yellow Sea is relatively low with the value being around 5 µg/L. (2). Taking full advantage of the continuous observation of geostationary orbit satellite, GF-4 with a high-resolution sensor PMS of 50 m can effectively detect short-term change (changes within 10 min) in Chla concentration. The changes mainly appear at the southwest and northeast costal area as well as in the center of Bohai Sea with the change value of around 3 µg/L. (3) The change of Chla concentration in the Bohai sea is related to the environmental factors such as seawater temperature, salinity, illumination and nutrient salts, as well as the dynamic factors such as wind, flow field and tidal current.

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Storm Surges in the Bohai Sea: The Role of Waves and Tides

Water ◽

10.3390/w12051509 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1509

Author(s):

Yuanyi Li ◽

Huan Feng ◽

Guillaume Vigouroux ◽

Dekui Yuan ◽

Guangyu Zhang ◽

...

Keyword(s):

Storm Surge ◽

Bohai Sea ◽

Storm Surges ◽

Wave Force ◽

Laizhou Bay ◽

Bohai Bay ◽

Coastal Regions ◽

The Bohai Sea ◽

Tidal Phase ◽

Set Up

A storm surge is a complex phenomenon in which waves, tide and current interact. Even though wind is the predominant force driving the surge, waves and tidal phase are also important factors that influence the mass and momentum transport during the surge. Devastating storm surges often occur in the Bohai Sea, a semi-enclosed shallow sea in North China, due to extreme storms. However, the effects of waves on storm surges in the Bohai Sea have not been quantified and the mechanisms responsible for the higher surges that affect part of the Bohai Sea have not been thoroughly studied. In this study, we set up a storm surge model, considering coupled effects of tides and waves on the surges. Validation against measured data shows that the coupled model is capable of simulating storm surges in the Bohai Sea. The simulation results indicate that the longshore currents, which are induced by the large gradient of radiation stress due to wave deformation, are one of the main contributors to the higher surges occurring in some coastal regions. The gently varying bathymetry is another factor contributing to these surges. With such bathymetry, the wave force direction is nearly uniform, and pushes a large amount of water in that direction. Under these conditions, the water accumulates in some parts of the coast, leading to higher surges in nearby coastal regions such as the south coast of the Bohai Bay and the west and south coasts of the Laizhou Bay. Results analysis also shows that the tidal phase at which the surge occurs influences the wave–current interactions, and these interactions are more evident in shallow waters. Neglecting these interactions can lead to inaccurate predictions of the storm surges due to overestimation or underestimation of wave-induced set-up.

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Spatio-temporal characteristics of the sea-ice volume of the Bohai Sea, China, in winter 2009/10

Annals of Glaciology ◽

10.3189/2013aog62a305 ◽

2013 ◽

Vol 54 (62) ◽

pp. 97-104 ◽

Cited By ~ 9

Author(s):

Chengyu Liu ◽

Wei Gu ◽

Jinlong Chao ◽

Lantao Li ◽

Shuai Yuan ◽

...

Keyword(s):

Sea Ice ◽

Bohai Sea ◽

Shortwave Radiation ◽

Laizhou Bay ◽

Bohai Bay ◽

Temporal Characteristics ◽

The Bohai Sea ◽

Ice Volume ◽

Radiation Theory ◽

Spatio Temporal

AbstractTo investigate the spatio-temporal characteristics of sea-ice resource, we used sea-ice volume to measure the amount of sea-ice resource in the Bohai Sea, China. The sea-ice area was extracted from Advanced Very High Resolution Radiometer (AVHRR) remote-sensing images using the zonal threshold method. The sea-ice thickness was estimated using a sea-ice model based on shortwave radiation theory and field measurements. The spatio-temporal characteristics of sea-ice volume were then analysed using GIS technology. The results indicate that the Bohai Sea experienced two sea-ice volume peaks in winter 2009/10. The largest sea-ice volume was in Liaodong Bay (∼80.26% of the entire sea-ice volume of the Bohai Sea). Bohai Bay had the second largest ice volume, and Laizhou Bay the smallest. The relationship between sea-ice volume and distance from shore is essentially exponential. The proportion of total sea-ice volume that is 0–10 km from shore is ∼42.43%, whereas the proportion that is 100–110 km from shore is only 0.002%.

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Estimating submarine groundwater discharges of the Bohai Sea, China using radium, hydrogen and oxygen isotopes and salinity

10.5194/egusphere-egu2020-6644 ◽

2020 ◽

Author(s):

Hailong Li ◽

Xiaolang Zhang ◽

Xuejing Wang ◽

Kai Xiao ◽

Yan Zhang ◽

...

Keyword(s):

Steady State ◽

Mass Balance ◽

River Water ◽

Bohai Sea ◽

Balance Model ◽

Laizhou Bay ◽

Bohai Bay ◽

Fresh Groundwater ◽

The Bohai Sea ◽

Submarine Groundwater

With an area of about 77,000 km2, the Bohai Sea includes three bays: Laizhou Bay, Bohai Bay and Liaodong Bay. In this study, 228Ra, &#948;D, &#948;18O and salinity data were collected from surface seawater in the entire Bohai Sea, river water, and groundwater along its coastline in August 2017. Based on the spatial distributions of &#948;D, &#948;18O, and salinity in surface water in the entire Bohai Sea and &#948;D-salinity relations, the marine hydrological processes were investigated and the members of river water and groundwater for &#948;D and &#948;18O were determined. The steady-state mass-balance models of &#948;D, &#948;18O and salinity are given and used to estimate submarine fresh groundwater discharges and the flushing times of the entire Bohai Sea and its three bays. Based on the results of the flushing times, the steady-state mass-balance model of 228Ra is used to estimate submarine groundwater discharges of the entire Bohai Sea and its three bays.

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Combined Effect of Tides and Wind on Water Exchange in a Semi-Enclosed Shallow Sea

Water ◽

10.3390/w11091762 ◽

2019 ◽

Vol 11 (9) ◽

pp. 1762 ◽

Cited By ~ 5

Author(s):

Jiancheng Shang ◽

Jian Sun ◽

Lei Tao ◽

Yuanyi Li ◽

Zhenhua Nie ◽

...

Keyword(s):

Half Life ◽

Water Exchange ◽

Bohai Sea ◽

Numerical Models ◽

The Yellow Sea ◽

Laizhou Bay ◽

Bohai Bay ◽

Tracer Transport ◽

Shallow Sea ◽

The Bohai Sea

The Bohai Sea is a semi-enclosed shallow sea in China, where the tides and wind are the dominant factors contributing to the water exchange with the Yellow Sea. However, existing studies on this water exchange primarily consider only the effect of tidal action, neglecting the contribution of wind. In this study, numerical models were used to simulate the hydrodynamic processes and tracer transport, with the consideration of both tides and wind. Based on the models, the two time scales, age and half-life, are applied to study the water exchange in the Bohai Sea quantitatively. The results show that the age and half-life decrease significantly when wind is included in the simulation, revealing that wind is an important contributor to the water exchange in such a semi-enclosed shallow sea. Under the combined forcing of tides and wind, the water transport in the Bohai Sea becomes clockwise, in contrast with the counterclockwise transport driven by the tides only. The seasonal-varying wind leads to a fluctuation of water exchange in an annual cycle, with the stronger water exchange in the northern (Liaodong Bay) and the western (Bohai Bay) regions of the Bohai Sea in winter and in the southern part (Laizhou Bay) in summer.

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Response of Ecosystem Service Values to Environmental Change in the Bohai Sea

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.1321 ◽

2012 ◽

Vol 518-523 ◽

pp. 1321-1324 ◽

Cited By ~ 2

Author(s):

An Ning Suo ◽

Xu Bin Pan ◽

Jian Hua Zhao ◽

Yong Hai Yu

Keyword(s):

Ecosystem Services ◽

Ecosystem Service ◽

Bohai Sea ◽

Marine Ecosystem ◽

Laizhou Bay ◽

The Bohai Sea ◽

Ecosystem Services Value ◽

Climate Regulation ◽

Marine Ecosystem Services ◽

O2 Supply

Since 1988, great changes of primary production, pollutants loading, coastline and sea area have happened in the Bohai Sea in China. These environmental changes increased the value of marine ecosystem services value from 529.42 billion RMB in 1988 to 558.83 billion RMB in 2010. The ecosystem services values of recreation, food and materials production, O2 supply, climate regulation and primary productivity were raised. However, other marine ecosystem services value, including biological control, pollutant purification, knowledge broaden and biodiversity protection were lowered. In addition, value of ecosystem services increased in Liaodong Bay and Bohai Bay, but decreased in middle Bohai and Bohai strait, and it no change in Laizhou Bay,.This spatial difference of ecosystem service function value was mainly caused by the change of recreation function, O2 supply function and climate regulation function.

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Biogeochemistry of dimethylsulfoniopropionate, dimethylsulfide and acrylic acid in the Yellow Sea and the Bohai Sea during autumn

Environmental Chemistry ◽

10.1071/en15025 ◽

2016 ◽

Vol 13 (1) ◽

pp. 127 ◽

Cited By ~ 11

Author(s):

Yue Liu ◽

Chun-Ying Liu ◽

Gui-Peng Yang ◽

Hong-Hai Zhang ◽

Sheng-hui Zhang

Keyword(s):

Acrylic Acid ◽

Chlorophyll A ◽

Yellow Sea ◽

Bohai Sea ◽

Sulfur Cycle ◽

The Yellow Sea ◽

Trace Gas ◽

The Bohai Sea ◽

Marginal Seas ◽

High Concentrations

Environmental context Dimethylsulfide (DMS) is a climatically important biogenic trace gas that is emitted from oceans. This research focuses on the spatiotemporal distributions of DMS and its related compounds, i.e. dimethylsulfoniopropionate (DMSP) and acrylic acid (AA), and the influencing factors in the Yellow Sea and the Bohai Sea during autumn. In addition, the sea-to-air flux of DMS, kinetic responses of DMSP consumption as well as DMS and AA production are also investigated. This study is helpful in understanding the marine sulfur cycle in marginal seas in China. Abstract The biogeochemistry of dimethylsulfoniopropionate (DMSP), dimethylsulfide (DMS) and acrylic acid (AA) in the Yellow Sea (YS) and the Bohai Sea (BS) was investigated in November 2013. The concentrations (and ranges) of total DMSP (DMSPt), dissolved DMSP (DMSPd), DMS and AA in surface waters were 30.71 (1.07–122.50), 6.60 (0.85–35.67), 1.48 (0.53–5.32) and 42.2 (13.8–352.8) nmol L–1 respectively. The concentrations of DMSPd and AA were positively correlated with chlorophyll-a levels, which suggests that phytoplankton biomass has an important function in controlling DMSPd and AA distributions. Furthermore, DMS and AA concentrations revealed significant positive relationships with DMSPd concentrations. The average ratios of AA/(DMSP+AA) and DMS/AA were 53.98 and 7.62% respectively. The vertical profiles of DMSP, DMS and AA were characterised by high concentrations that mostly occur near the surface. Even under highly variable hydrographic conditions, a positive relationship was observed between DMSPt and chlorophyll-a concentrations. The rates of DMSPd consumption, as well as DMS and AA production, significantly varied with marine environments. The sea-to-air fluxes of DMS from the YS and the BS to the atmosphere were estimated to be in the range of 3.01 to 6.91μmol m–2day–1.

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Organophosphate esters in sediment cores from coastal Laizhou Bay of the Bohai Sea, China

The Science of The Total Environment ◽

10.1016/j.scitotenv.2017.06.259 ◽

2017 ◽

Vol 607-608 ◽

pp. 103-108 ◽

Cited By ~ 25

Author(s):

Yan Wang ◽

Xiaowei Wu ◽

Qiaonan Zhang ◽

Minmin Hou ◽

Hongxia Zhao ◽

...

Keyword(s):

Bohai Sea ◽

Sediment Cores ◽

Laizhou Bay ◽

Organophosphate Esters ◽

The Bohai Sea

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Data assimilation in a coupled physical-biological model for the Bohai Sea and the Northern Yellow Sea

Marine and Freshwater Research ◽

10.1071/mf07144 ◽

2008 ◽

Vol 59 (6) ◽

pp. 529 ◽

Cited By ~ 7

Author(s):

Qing Xu ◽

Hui Lin ◽

Yuguang Liu ◽

Xianqing Lv ◽

Yongcun Cheng

Keyword(s):

Chlorophyll A ◽

Annual Cycle ◽

Yellow Sea ◽

Bohai Sea ◽

Biological Model ◽

Model Parameters ◽

The Bohai Sea ◽

Northern Yellow Sea ◽

Ocean Models ◽

Adjoint Assimilation

One difficulty with coupled physical-biological ocean models is determining optimal values of poorly known model parameters. The variational adjoint assimilation method is a powerful tool for the automatic estimation of parameters. We used this method to incorporate remote-sensed chlorophyll-a data into a coupled physical-biological model developed for the Bohai Sea and the Northern Yellow Sea. A 3-D NPZD model of nutrients (N), phytoplankton (P), zooplankton (Z) and detritus (D) was coupled with a physical model, the Princeton Ocean Model. Sensitivity analysis was carried out to choose suitable control variables from the model parameters. Numerical twin experiments were then conducted to demonstrate whether the spatio-temporal resolutions of the observations were adequate for estimating values of the control variables. Finally, based on the success of the twin experiments, we included remote-sensed chlorophyll-a data in the NPZD model. With the adjoint assimilation of these chlorophyll-a data, the coupled model better describes spring and autumn phytoplankton blooms and the annual cycle of phytoplankton at the surface layer for the study area. The annual cycle of simulated surface nutrient concentrations also agreed well with field observations. The adjoint method greatly improves the modelling capability of coupled ocean models, helping us to better understand and model marine ecosystems.

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Water conservancy project on the Yellow River modifies the seasonal variation of Chlorophyll-a in the Bohai Sea

Chemosphere ◽

10.1016/j.chemosphere.2020.126846 ◽

2020 ◽

Vol 254 ◽

pp. 126846

Author(s):

Xiaokun Ding ◽

Xinyu Guo ◽

Chao Zhang ◽

Xiaohong Yao ◽

Sumei Liu ◽

...

Keyword(s):

Seasonal Variation ◽

Chlorophyll A ◽

Bohai Sea ◽

Yellow River ◽

The Yellow River ◽

The Bohai Sea ◽

Water Conservancy Project ◽

Water Conservancy

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General Concerns Life-Cycle Design of Economical Ice-Resistant Structures in the Bohai Sea

Polish Maritime Research ◽

10.1515/pomr-2017-0079 ◽

2017 ◽

Vol 24 (s2) ◽

pp. 164-171

Author(s):

Da-yong Zhang ◽

Song-song Yu ◽

Qian-jin Yue

Keyword(s):

Life Cycle ◽

Life Cycle Cost ◽

Design Theory ◽

Bohai Sea ◽

Cost Effective ◽

Bohai Bay ◽

Offshore Platforms ◽

The Bohai Sea ◽

Life Cycle Design ◽

Whole Life Cycle

Abstract In China, the oil and natural gas resources of Bohai Bay are mainly marginal oil fields. It is necessary to build both iceresistant and economical offshore platforms. However, there are many risks during the life cycle of offshore platforms due to the imperfect preliminary design for the Bohai Sea economical ice-resistant structures. As a result, the whole life-cycle design should be considered, including plan, design, construction, management and maintenance design. Based on the demand of existing codes and research of the basic design, structural ice-resistant performance and the reasonable management and maintenance, the life-cycle design theory is discussed. It was concluded that the life-cycle cost-effective optimum design proposed will lead to a minimum risk.

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