Experiments in optimizing simulations of the subsurface chlorophyll maximum in the South China Sea

Wang, Siying; Li, Shiyu; Hu, Jiatang; Geng, Bingxu

doi:10.1016/j.jmarsys.2015.11.003

Cited by 9 publications

(7 citation statements)

References 60 publications

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“…22 (a)), and the Chl-a concentration in the South China Sea is about 0.5 mg/m³ (Fig. 22 (b) and (c)), which agree with those observed in literatures [42][43][44]. In addition, surface water samples (0-50 cm) were collected while the spectra were being collected.…”

Section: ) Chl-a Concentrations From Case II Waters To Case I Waterssupporting

confidence: 88%

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Design of a Novel Fully Automatic Ocean Spectra Acquisition and Control System Based on the Real-Time Solar Angle Analyzing and Tracking

Yang

Gao

et al. 2021

IEEE Access

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The current manual spectra acquisition for monitoring water constituents has resulted in discontinuous data acquisition, insufficient amount of data, and small ocean coverage. This paper presents the design of a novel fully automatic ocean spectra acquisition and control system based on the real-time solar angle analyzing and tracking. To ensure that the requirements for spectra acquisition are met, the system is capable of accurately calculating the solar angle by collecting the information of latitude, longitude, date, time and direction, and automatically adjusting the position of instrument observation plane and the pointing angle of fiber optic probe in real-time. It achieves full automation of collecting the downward radiance of skylight, the upward radiance from reference panel and seawater separately through controlling the rotation of fiber optic probe. A 188-day observation experiment was carried out at the coastal ocean experimental station in Qingdao from September 11, 2018 to March 17, 2019. After that, the system was conducted onboard the Dongfanghong 3 scientific research vessel for a one-month demonstration and sea trial in June 2019. Comparative experiments including manual spectra collection, chlorophyll-a sensor measurement, and water samples collection were carried out. The experimental results show that the relative error of the spectra between the system and manual collection is less than 5%, and the relative error of the remote sensing reflectance calculated by the spectra is less than 4%. Considering the chlorophyll-a concentration obtained by the sensor and the water samples as the true value, the relative error of the chlorophyll-a concentration obtained by the system is 10% and 25% respectively. The results show its full and reliable capacity in collecting spectra of seawater automatically and continuously in real-time, with satisfactory accuracy and timeliness.

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Section: ) Chl-a Concentrations From Case II Waters To Case I Waterssupporting

confidence: 88%

“…The remote sensing reflectance of the South China Sea shows a downward trend as the wavelength increases, as shown in Fig. 21 (c) and (f), which is in line with the general trend of the remote sensing reflectance of the Case I waters [42]. In Fig.…”

Section: ) Remote Sensing Reflectance In Different Sea Areassupporting

confidence: 82%

Design of a Novel Fully Automatic Ocean Spectra Acquisition and Control System Based on the Real-Time Solar Angle Analyzing and Tracking

Yang

Gao

et al. 2021

IEEE Access

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“…Consequently, the cold surface temperature modifies the typhoon intensity by blocking the following typhoons from gaining energy from the warm ocean surface [6,7]. Thus, single typhoons usually trigger substantial sea surface cooling and sea surface chlorophyll (CHL) blooms [8,9], but the impacts of sequential typhoons are much less pronounced [10].…”

Section: Introductionmentioning

confidence: 99%

Modulation Effect of Mesoscale Eddies on Sequential Typhoon-Induced Oceanic Responses in the South China Sea

Jin

Liang

et al. 2020

Remote Sensing

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The impacts of mesoscale eddies on the modulation of typhoon-induced oceanic responses are important for understanding ocean dynamics. Satellite observations identified prominent ocean surface temperature and chlorophyll changes over the regions with mesoscale eddies after two sequential typhoons, e.g., Linfa and Nangka, in the South China Sea. The impacts of typhoons on the ocean surface were more prominent within cyclonic eddies than within anticyclonic eddies. The wind speed (translation speed) of Linfa was much larger (slower) than that of Nangka; thus, the changes induced by Linfa were stronger. However, the second typhoon easily generated mixing through the weak stratification induced by the first typhoon and impacted the upper ocean. The strong chlorophyll enhancement induced by Nangka was identified at a cyclonic eddy. Using a combination of reanalysis data, the depth of water origin (DWO) was applied to quantify the depth to which a typhoon’s impact could be exerted. Prominent changes were identified when the DWO reached the depth at which the temperature and nutrients differed from those within the mixed layer. This method can overcome the impacts of cloud coverage when examining a typhoon’s influence with remotely sensed data and offers a quantitative approach to determine the mechanisms responsible for typhoon-induced ocean surface changes.

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“…Viral abundance is known to fluctuate with bacterial variation, which is coupled with organic matter supply. The subsurface chlorophyll maximum (SCM, also known as the deep chlorophyll maximum, DCM) exists near the bottom of the surface mixed layer or the top of the pycnocline and nutricline in the water column in oligotrophic oceans (Cullen, 2015); it is also a common permanent feature in the SCS observed in many studies (Lu et al, 2010; Wang et al, 2015). As phytoplankton have access to nutrients at the nutricline, they can carry out photosynthesis and produce organic matter at the SCM layer.…”

Section: Discussionmentioning

confidence: 99%

Double Maximum Ratios of Viruses to Bacteria in the Water Column: Implications for Different Regulating Mechanisms

Yin

Yuan

2019

Front. Microbiol.

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The viruses play an important role in limiting bacterial abundance in oceans and, hence, in regulating bacterial biogeochemical functions. A cruise was conducted in September 2005 along a transect in the deep South China Sea (SCS). The results showed the double maxima in the ratio of viral to bacterial abundance (VBR) in the water column: a deep maximum at 800–1000 m coinciding with the oxygen minimum zone (OMZ) and a subsurface maximum at 50–100 m near the subsurface chlorophyll maximum (SCM) layer. At the deep maximum of VBR, both viral and bacterial abundances were lower than those in the upper layer, but the former was reduced less than the latter. In contrast, at the subsurface maximum of VBR, both viral and bacterial abundances increased to the maximum, with viral abundance increasing more than bacterial abundance. The results suggest that two VBR maxima were formed due to different mechanisms. In the SCM, the VBR maximum is due to an abundant supply of organic matter, which increases bacterial growth, and stimulates viral abundance faster. In contrast, in the OMZ, organic matter is consumed and limits bacterial growth, but viruses are less limited by organic matter and continue to infect bacteria, leading to the maximum VBR. The OMZ in the deep-water column of oceans is over hundreds of years old and receives a constant supply of organic matter from the water above. However, the oxygen level cannot be depleted to anoxia. Bacterial respiration is largely responsible for oxygen consumption in the OMZ; and hence, any process that limits bacterial abundance and respiration contributes to the variation in the OMZ. Viral control of bacterial abundance can be a potential mechanism responsible for slowing down oxygen consumption to anoxia in the OMZ. Our finding provides preliminary evidence that viruses are an important player in controlling bacterial abundance when bacterial growth is limited by organic matter, and thus, regulates the decomposition of organic matter, oxygen consumption and nutrient re-mineralization in deep oceans.

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Experiments in optimizing simulations of the subsurface chlorophyll maximum in the South China Sea

Cited by 9 publications

References 60 publications

Design of a Novel Fully Automatic Ocean Spectra Acquisition and Control System Based on the Real-Time Solar Angle Analyzing and Tracking

Design of a Novel Fully Automatic Ocean Spectra Acquisition and Control System Based on the Real-Time Solar Angle Analyzing and Tracking

Modulation Effect of Mesoscale Eddies on Sequential Typhoon-Induced Oceanic Responses in the South China Sea

Double Maximum Ratios of Viruses to Bacteria in the Water Column: Implications for Different Regulating Mechanisms

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