scholarly journals Phytoplankton Genera Structure Revealed from the Multispectral Vertical Diffuse Attenuation Coefficient

2021 ◽  
Vol 13 (20) ◽  
pp. 4114
Author(s):  
Cleber Nunes Kraus ◽  
Daniel Andrade Maciel ◽  
Marie Paule Bonnet ◽  
Evlyn Márcia Leão de Moraes Novo
Keyword(s):  
Light Intensity ◽  
Attenuation Coefficient ◽  
Light Availability ◽  
Green Light ◽  
Phytoplankton Diversity ◽  
Diffuse Attenuation Coefficient ◽  
Amazon Floodplain ◽  
Phytoplankton Communities ◽  
Spectral Ranges

The composition of phytoplankton and the concentration of pigments in their cells make their absorption and specific absorption coefficients key parameters for bio-optical modeling. This study investigated whether the multispectral vertical diffuse attenuation coefficient of downward irradiance (Kd) gradients could be a good framework for accessing phytoplankton genera. In situ measurements of remote sensing reflectance (Rrs), obtained in an Amazon Floodplain Lake (Lago Grande do Curuai), were used to invert Kd, focusing on Sentinel-3/Ocean and Land Color Instrument (OLCI) sensor bands. After that, an analysis based on the organization of three-way tables (STATICO) was applied to evaluate the relationships between phytoplankton genera and Kd at different OLCI bands. Our results indicate that phytoplankton genera are organized according to their ability to use light intensity and different spectral ranges of visible light (400 to 700 nm). As the light availability changes seasonally, the structure of phytoplankton changes as well. Some genera, such as Microcystis, are adapted to low light intensity at 550–650 nm, therefore high values of Kd in this range would indicate the dominance of Microcysts. Other genera, such as Aulacoseira, are highly adapted to harvesting blue-green light with higher intensity and probably grow in lakes with lower concentrations of colored dissolved organic matter that highly absorbs blue light (405–498). These findings are an important step to describing phytoplankton communities using orbital data in tropical freshwater floodplains. Furthermore, this approach can be used with biodiversity indexes to access phytoplankton diversity in these environments.

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.

TROPOMI's potential for ocean applications

2020 ◽  
Author(s):  
Julia Oelker ◽  
Svetlana Losa ◽  
Mariana Altenburg Soppa ◽  
Andreas Richter ◽  
Astrid Bracher
Keyword(s):  
Attenuation Coefficient ◽  
Heat Budget ◽  
Solar Spectrum ◽  
Optical Absorption Spectroscopy ◽  
Fluorescence Signal ◽  
Data Sets ◽  
Phytoplankton Diversity ◽  
Diffuse Attenuation Coefficient ◽  
Underwater Light Field ◽  
Surface Ocean

<p>The backscattered light from within the ocean carries information about surface ocean optical constituents, e.g., phytoplankton and the amount of light in the ocean. Global quantified insight in these parameters is important for estimating primary productivity and heat budget, and for a better understanding and modeling of biogeochemical cycles. Atmospheric sensors such as SCIAMACHY and GOME-2 have proven to yield valuable information on phytoplankton diversity, sun-induced marine fluorescence, and the underwater light field. As commonly used for the retrieval of atmospheric trace gases, the oceanic parameters are inferred from differential optical absorption spectroscopy combined with radiative transfer modeling. Within the ESA Sentinel-5p+ Innovation themes, we explore TROPOMI's potential for deriving the diffuse attenuation coefficient, quantification of different phytoplankton groups and the fluorescence signal of phytoplankton. Here we present results on deriving the diffuse attenuation coefficient from the vibrational Raman scattering signal in backscattered radiances measured by TROPOMI. The diffuse attenuation coefficient describes how fast the incoming radiation in the ocean is diminished with depth. Retrieval results in three spectral regions covering the ultraviolet and blue region of the solar spectrum are presented and intercompared. In future, we will explore if information on sources of colored dissolved organic matter and ultraviolet-absorbing phytoplankton pigments can be inferred from these data sets.</p>

Mapping of diffuse attenuation coefficient in optically complex waters of amazon floodplain lakes

2020 ◽  
Vol 170 ◽  
pp. 72-87
Author(s):  
Daniel Andrade Maciel ◽  
Claudio Clemente Faria Barbosa ◽  
Evlyn Márcia Leão de Moraes Novo ◽  
Nagur Cherukuru ◽  
Vitor Souza Martins ◽  
...  
Keyword(s):  
Attenuation Coefficient ◽  
Floodplain Lakes ◽  
Diffuse Attenuation Coefficient ◽  
Amazon Floodplain

The potential of Sentinel-5P’s high spectral resolution for ocean applications

2021 ◽  
Author(s):  
Astrid Bracher ◽  
Julia Oelker ◽  
Svetlana Losa ◽  
Mariana Altenburg Soppa ◽  
Andreas Richter ◽  
...  
Keyword(s):  
Attenuation Coefficient ◽  
Spectral Range ◽  
Short Wave ◽  
High Spectral Resolution ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Phytoplankton Diversity ◽  
Diffuse Attenuation Coefficient ◽  
In Situ Data ◽  
Spatial Coverage

<p>Hyperspectral satellite data are a source of the top of the atmosphere radiance signal which can be used for novel algorithms aimed for observations of marine ecosystems and the light-lit ocean. Atmospheric sensors such as SCIAMACHY, GOME-2 and OMI have proven in the past to yield valuable information on phytoplankton diversity, sun-induced marine fluorescence, and the underwater light field, however at low coverage and spatial resolution. Within the ESA Sentinel-5p+ Innovation themes, we explore TROPOMI's potential for deriving the diffuse attenuation coefficient and the quantification of different phytoplankton groups. As commonly used for the retrieval of atmospheric trace gases, we apply the differential optical absorption spectroscopy combined with radiative transfer modeling (RTM) to infer these oceanic parameters. We present results on a measure describing the diminishing of incoming radiation in the ocean with depth, the diffuse attenuation coefficient KD. KD is derived by the retrieval of the vibrational Raman scattering signal in backscattered radiances measured by TROPOMI in the UV and spectral range which then is further converted to the associated KD using RTM. The final TROMPOMI KD data sets resolved for three spectral regions (UV-B+short wave UV-A, UV-A and short blue) agree well with in situ data sampled during an expedition with RV Polarstern in 2018 in the Atlantic Ocean.  Further, KD-blue compared to wavelength-converted KD(490nm) products (OLCI-A and the merged OC-CCI) from common, multispectral, ocean color sensors, show that differences between the three data sets are within uncertainties given for the OC-CCI product. Our study shows for the first time KD products for the UV spectral range retrieved from space based data. TROPOMI KD-blue results have higher quality and much higher spatial coverage and resolution than previous ones from SCIAMACHY, GOME-2 and OMI.  Additionally, first results on TROPOMI’s potential for retrieving three phytoplankton groups will be shown and compared to similar multispectral phytoplankton group data for the same time period and ocean region as shown for TROPOMI KD.</p>

scholarly journals IN-SITU MEASUREMENT OF DIFFUSE ATTENUATION COEFFICIENT AND ITS RELATIONSHIP WITH WATER CONSTITUENT AND DEPTH ESTIMATION OF SHALLOW WATERS BY REMOTE SENSING TECHNIQUE

2017 ◽  
Vol 14 (1) ◽  
pp. 47
Author(s):  
Budhi Agung Prasetyo ◽  
Vincentius Paulus Siregar ◽  
Syamsul Bahri Agus ◽  
Wikanti Asriningrum
Keyword(s):  
Attenuation Coefficient ◽  
Water Depth ◽  
Depth Estimation ◽  
In Situ Measurement ◽  
Shallow Waters ◽  
Landsat 8 ◽  
Band Ratio ◽  
Diffuse Attenuation Coefficient ◽  
The Relationship

Diffuse attenuation coefficient, Kd(λ), has an empirical relationship with water depth, thus potentially to be used to estimate the depth of the water based on the light penetration in the water column. The aim of this research is to assess the relationship of diffuse attenuation coefficient with the water constituent and its relationship to estimate the depth of shallow waters of Air Island, Panggang Island and Karang Lebar lagoons and to compare the result of depth estimation from Kd model and derived from Landsat 8 imagery. The measurement of Kd(λ) was carried out using hyperspectral spectroradiometer TriOS-RAMSES with range 320 – 950 nm. The relationship between measurement Kd(λ) on study site with the water constituent was the occurrence of absorption by chlorophyll-a concentration at the blue and green spectral wavelength. Depth estimation using band ratio from Kd(λ) occurred at 442,96 nm and 654,59 nm, which had better relationship with the depth from in-situ measurement compared to the estimation based on Landsat 8 band ratio. Depth estimated based on Kd(λ) ratio and in-situ measurement are not significantly different statistically. Depth estimated based on Kd(λ) ratio and in-situ measurement are not significantly different statistically. However, depth estimation based on Kd(λ) ratio was inconsistent due to the bottom albedo reflection because the Kd(λ) measurement was carried out in shallow waters. Estimation of water depth based on Kd(λ) ratio had better results compared to the Landsat 8 band ratio.

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