scholarly journals Influence of Coccolithophore Blooms on the Bio-Optical Characteristics of the Black Sea Waters according to Observations in 2012 and 2017

2020 ◽  
Author(s):  
E. N. Korchemkina ◽  
E. V. Mankovskaya ◽  
R.I. Lee ◽  
◽  
◽  
...  
Keyword(s):  
Attenuation Coefficient ◽  
Black Sea ◽  
Biological Properties ◽  
Biological Data ◽  
The Black Sea ◽  
Secchi Disk ◽  
Secchi Disk Depth ◽  
Beam Attenuation ◽  
Reflectance Coefficient ◽  
Beam Attenuation Coefficient

This paper presents and discusses the results of optical and biological measurements performed during the coccolithophore blooms. This study uses data of measurements from a stationary oceanographic platform (near the Southern coast of Crimea, 44°23' N, 33°59' E) in July 2012 (7–16 July) and in May 2017 (24–31 May), and data obtained during the R/V “Professor Vodyanitsky” expedition to the northern part of the Black Sea in June 2017 (14–30 June). Observation periods coincided with intensive blooms of coccolithophore. The measurements of the Secchi disk depth, light beam attenuation coefficient and reflectance coefficient, as well as biological determinations of the coccolithophore cells number in water samples, are considered and analyzed. In addition to field data, satellite information on the sea reflectance and backscattering are used. The beam attenuation coefficient, reflectance coefficient, backscattering coefficient and coccolithophore concentrations were increased as compared with no bloom period. The Secchi disk depth was abnormally low. The number of coccolithophore cells, according to biological data, varied from 150 thousand cells/L to 1.7 million cells/L and averaged 0.6 ± 0.4 million cells/L. According to these data, the estimated concentration of shed coccoliths was (1.46 ± 0.42) 1011 m-3 . The average coccolith concentrations calculated from satellite data were (1.29 ± 0.23) 1011 m-3 in July 2012, (1.32 ± 0.12) 1011 m-3 in May 2017, and (2.37 ± 0.69) 1011 m-3 in June 2017. During blooms, high variability was observed not only in optical properties, but also in biological properties, and the relationship between their spatial distribution was weak. From the optical point of view, the indicator of bloom is the number of coccoliths, not cells, which can lead to an incorrect description of the biological situation.

The vertical structure of the water column according to optical data

2021 ◽  
pp. 245-252
Author(s):  
V.I. Burenkov ◽  
◽  
V.A. Artemiev ◽  
Keyword(s):  
Attenuation Coefficient ◽  
Barents Sea ◽  
Optical Data ◽  
Time Variability ◽  
Beam Attenuation ◽  
The Barents Sea ◽  
Close Relationship ◽  
Suspended Matter Concentration ◽  
High Space ◽  
Beam Attenuation Coefficient

Vertical profiles of the beam attenuation coefficient in different regions of the Barents Sea are analyzed. Data obtained show high space-time variability of seawater optical properties. In particular, the area affected by the river inflow (Pechora Sea) is distinguished. Very high values of the beam attenuation coefficient are observed in areas of coccolithophore blooms. There are a number of features associated with the flow of Atlantic waters into the Barents Sea. A close relationship between the seawater beam attenuation coefficient and total suspended matter concentration is shown. The corresponding regression equation is obtained.

Calculating Irradiance Penetration into Water Bodies from the Measured Beam Attenuation Coefficient, II: Application of the Improved Model to Different Types of Lakes

2002 ◽  
Vol 33 (2-3) ◽  
pp. 227-240 ◽  
Author(s):  
Helgi Arst ◽  
Ants Erm ◽  
Anu Reinart ◽  
Liis Sipelgas ◽  
Antti Herlevi
Keyword(s):  
Attenuation Coefficient ◽  
Water Samples ◽  
Water Bodies ◽  
Diffuse Attenuation Coefficient ◽  
Beam Attenuation ◽  
Underwater Light Climate ◽  
Different Types ◽  
Underwater Irradiance ◽  
Beam Attenuation Coefficient

The method suggested earlier for estimating the spectra of diffuse attenuation coefficient of light in the water bodies relying on the beam attenuation coefficient measured from water samples, was improved and applied to different types of lakes. Measurement data obtained in 1994-95 and 1997-98 for 18 Estonian and Finnish lakes were used. The spectra of two characteristics were available for our investigations: 1) beam attenuation coefficient estimated from water samples in the laboratory with a spectrophotometer Hitachi U1000; 2) vertical irradiance (diffuse) attenuation coefficient measured in situ with an underwater spectroradiometer LI 1800UW. A total of 70 spectra were considered. Relying on these data the parameters of our earlier model were changed. The criterion of the efficiency of the new version of our model is the coincidence of the spectra of diffuse attenuation coefficient derived from Hitachi U1000 data (Kdc) with those obtained by underwater irradiance measurements (Kdm). Correlation analysis of the model's results gave the relationship Kdm=1.0023Kdc with correlation coefficient 0.961. The respective values of mean relative difference and standard deviation were 5.4% and 0.55 m−1. This method may be useful in conditions where in situ measuring of underwater irradiance spectra cannot be performed because of weather conditions. As the measurement of the underwater radiation field is often a complicated and expensive procedure, our numerical method may be useful for estimating the underwater light climate.

Turbidity in the northern Great Barrier Reef lagoon in the wet season, March 1989

1994 ◽  
Vol 45 (4) ◽  
pp. 585 ◽  
Author(s):  
LJ Hamilton
Keyword(s):  
Great Barrier Reef ◽  
Attenuation Coefficient ◽  
Quantitative Relation ◽  
Barrier Reef ◽  
Wet Season ◽  
Secchi Disc ◽  
Reef Lagoon ◽  
Secchi Disc Depth ◽  
Beam Attenuation ◽  
Beam Attenuation Coefficient

In 1989, a typical wet season was experienced in northern Queensland, with low winds and long calm periods. Turbidity in upper waters of the Great Barrier Reef lagoon broadly had a simple distribution that could be modelled from bottom depth contour values alone, without introducing wind speed or bottom type. In the absence of major storm and cyclone events, this result appears to be general, based on the similarity between March 1989 survey data and Secchi disc climatology. The simple distribution arises because the main turbidity sources are riverine discharges, with little entrainment of bottom sediment into the upper column, except in shallower waters. Fresh, highly turbid riverine influxes are generally confined close inshore, with salinity and Secchi contours parallel to shore, forming cross-shelf gradients. A semi-quantitative relation was found between sea surface colour and Secchi disc depth. Examination of nephelometric turbidity stratification showed that satellite and Secchi data should be more useful for subsurface turbidity inference between Cooktown and Innisfail than in Princess Charlotte Bay, with horizontal and vertical stratifications, respectively, observed in those areas. Highest nephelometric turbidity was seen from Cooktown to Innisfail. Beam attenuation coefficient in oceanic waters outside the reef appeared to be dominated by absorption, with lagoon waters influenced by scattering. A method is suggested to enable approximate transfer of beam attenuation coefficient measured by a transmissometer operating at a single wavelength to beam attenuation coefficient at other wavelengths, using coincident measurements of Secchi disc depths made with filters.

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