Interannual-decadal variation in satellite-derived surface chlorophyll-a concentration in the Bohai Sea over the past 16 years

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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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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Temporal-spatial variations and developing trends of Chlorophyll-a in the Bohai Sea, China

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2016.02.016 ◽

2016 ◽

Vol 173 ◽

pp. 49-56 ◽

Cited By ~ 21

Author(s):

Yanzhao Fu ◽

Shiguo Xu ◽

Jianwei Liu

Keyword(s):

Chlorophyll A ◽

Bohai Sea ◽

Spatial Variations ◽

The Bohai Sea

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

Sensors ◽

10.3390/s20195471 ◽

2020 ◽

Vol 20 (19) ◽

pp. 5471

Author(s):

Lina Cai ◽

Juan Bu ◽

Danling Tang ◽

Minrui Zhou ◽

Ru Yao ◽

...

Keyword(s):

Chlorophyll A ◽

Bohai Sea ◽

Seawater Temperature ◽

Remote Sensing Data ◽

Geosynchronous Orbit ◽

Laizhou Bay ◽

Bohai Bay ◽

The Bohai Sea ◽

Dynamic Factors ◽

Chla Concentration

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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