Atmospheric correction of satellite optical data is based on an assessment of the optical charact... more Atmospheric correction of satellite optical data is based on an assessment of the optical characteristics of the atmosphere, such as the aerosol optical depth of the atmosphere and the spectral slope of its spectrum, the so-called Angstrom parameter. Inaccurate determination of these parameters is one of the causes of errors in the retrieval of the remote sensing reflectance spectra. In this work, the obtained large array of field and satellite data for the northeastern part of the Black Sea is used, including ship-based measurements of atmospheric characteristics and sea reflectance, MODIS Aqua/Terra and OLCI Sentinel-3 A/B Level 2 remote sensing reflectance and atmospheric data. The purpose of this study is to show the numerical differences between the atmospheric parameters measured from the surface level and from the satellite and demonstrate their relationship with the differences between in situ and satellite remote sensing reflectance. Based on the information received, we pr...
24th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics, 2018
The first results in development of method for satellite monitoring of the bio-optical water prop... more The first results in development of method for satellite monitoring of the bio-optical water properties of Gorky reservoir as an example of an inland freshwater eutrophic water body are presented. The method is based on the semi-analytical algorithm for the Black Sea and uses the data on the reflectance coefficient of the water column, allowing to calculate the concentrations of optically significant substances (phytoplankton pigments, dissolved organic matter and mineral suspended matter). Field measurements of spectral reflectance were carried out in years 2016 – 2017. Spatial variability of reflectance and factors affecting it were analyzed. Reflectance model used in Black Sea algorithm was adapted to biooptical features of the studied water body. Model calculations of pigment concentration were compared with chlorophyll a content data obtained from water samples analyses. The pigment absorption spectra were calculated, showing the spectral features characteristic of photosynthetic pigments. The ways of further research for algorithm development are determined.
Reflectance spectra were measured in situ in April-May 2019 in the north-eastern part of the Blac... more Reflectance spectra were measured in situ in April-May 2019 in the north-eastern part of the Black Sea, the water color characteristics were calculated. The relationships between effective wavelength of reflectance with other optical characteristics are shown. The absorption, vertical light attenuation, euphotic depth are analyzed taking into account the hydrological parameters of the test polygon. Optical water types of the test polygon were determined.
25th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics, 2019
The results of the sea water hydro-optical characteristics calculation from satellite and contact... more The results of the sea water hydro-optical characteristics calculation from satellite and contact data using a modified bio-optical model are presented. The research of the optical characteristics of sea water during the mass growth of coccolithophore is carried out. The estimates of the coccolith and chlorophyll concentration are obtained.
This paper is devoted to the study of the possibilities of restoring the concentrations of chloro... more This paper is devoted to the study of the possibilities of restoring the concentrations of chlorophyll-a (Chl-a) and total suspended matter (TSM) in fresh waterbodies using the images of Sentinel-2 / MSI of the Gorky reservoir as an example, validated via the high-resolution ground-truth data obtained by fluorescence lidar UFL. This water area in the period of intense chromaticity of cyanobacteria is distinguished by their completely heterogeneous spatial-temporal distribution with scales of patchiness from several tens of meters and high temporal variability. For this reason, direct methods of “spot” measurements in place on water samples in a small part of the reservoir for 3 hours relative to the satellite’s span do not provide us with reliable and statistically proved data. In this regard, the work proposed an original method of high-performance sub-satellite synchronous measurements of the brightness of the water column, concentrations of Chl-a and TSM with a fluorescent lidar ...
This paper presents and discusses the results of optical and biological measurements performed du... more 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...
The paper shows the results of optical measurements carried out during the coccolithophore bloom ... more The paper shows the results of optical measurements carried out during the coccolithophore bloom and the primary bio-optical characteristics obtained. Blooming coccolithophores produce a significant amount of mineral suspension, increasing light scattering and reducing the transparency of water. An increase in the backward scattering leads to an increase in the upwelling radiance and the reflectance coefficient of the sea water. On the base of field and satellite data, the characteristics of coccolithophore bloom in June 2017 in the Black Sea are calculated. A weak relationship between the biological and optical characteristics of the bloom is observed. It is shown that in 2017 the optical properties at the test site were determined not only by coccolithophore suspension, but also by a suspension of terrigenous origin. Suspension concentrations and optical parameters during the bloom are estimated.
The scattering characteristics of suspended matter in seawater obtained during combined processin... more The scattering characteristics of suspended matter in seawater obtained during combined processing of the field measurements data of the light beam attenuation coefficient and the information from satellite ocean-color scanners are presented. The model estimation of particles size composition is made. Percent of fine fraction of the suspension and its spatial distribution are shown to correlate with seasonal changes in hydrology of measurements polygon.
The goal of current investigation was a study of seasonal variability of remote sensing reflectan... more The goal of current investigation was a study of seasonal variability of remote sensing reflectance in the lake part of the Gorky reservoir, characterized by intense bloom of blue-green algae. The basis of this study includes the data of ship measurements of remote sensing reflectance, euphotic zone and chlorophyll a and dissolved organic carbon concentrations, performed from May 14, 2018 to August 27, 2018 in 7 points of the reservoir, two of which are located in shallow areas with a slow current (floodplain area), two - in the channel and the remaining three - in estuaries of three inflowing rivers. The spatial and temporal variability of remote sensing reflectance is analyzed, its variations are calculated, vertical profiles of chlorophyll a and dissolved organic carbon are constructed, variations of euphotic depth are determined and correlation between variations of remote sensing reflectance and concentrations of optically active components is established
The possibilities of chlorophyll a (Chl a) and total suspended matter (TSM) retrieval using Senti... more The possibilities of chlorophyll a (Chl a) and total suspended matter (TSM) retrieval using Sentinel-2/MSI imagery and in situ measurements in the Gorky Reservoir are investigated. This water body is an inland freshwater ecosystem within the territory of the Russian Federation. During the algal bloom period, the optical properties of water are extremely heterogeneous and vary on scales of tens of meters. Additionally, they vary in time under the influence of currents and wind forcing. In this case, the usage of the traditional station-based sampling to describe the state of the reservoir may be uninformative and not rational. Therefore, we proposed an original approach based on simultaneous in situ measurements of the remote sensing reflectance by a single radiometer and the concentration of water constituents by an ultraviolet fluorescence LiDAR from a high-speed gliding motorboat. This approach provided fast data collection including 4087 synchronized LiDAR and radiometric measure...
ABSTRACT A concentration-weighted trajectory method for aerosol source localization based on join... more ABSTRACT A concentration-weighted trajectory method for aerosol source localization based on joint statistical analysis of aerosol column volume concentrations and back-trajectory data was used to estimate the spatial distribution of aerosol sources in the East-European region. The aerosol column volume concentration data measured at five AERONET network sites, Belsk, Minsk, Kyiv, Moldova/Kishinev, and Sevastopol, were used. The geographical areas responsible for increased aerosol content at the monitoring sites were mapped separately for coarse-mode and fine-mode aerosol fractions. The investigated area is located between 42° and 62° N in latitude and between 12° and 50° E in longitude. It was shown that the northeastern territories (in relation to the monitoring stations) give a small contribution to the coarse-mode aerosol content. The events of increased coarse-mode aerosol concentration have been caused by sources in the southeastern regions. On average, the air masses with a large content of coarse-mode aerosol particles were delivered to all stations from regions around Donetsk, Rostov-on-Don, and Kharkiv cities. The fine-mode aerosol fraction originated from areas of Tambov, Voronezh, and Kharkiv cities. The calculated aerosol source regions partly correspond to European Monitoring and Evaluation Programme data for eastern Europe. The cause of difference between calculated regions responsible for increased aerosol content at the monitoring sites and the sources of particle emission according to European Monitoring and Evaluation Programme data are discussed. http://www.tandfonline.com/eprint/j99ACAgV2rNeP7uJ8CAR/full
We present the results of measurements of optical characteristics of waters (the beam attenuation... more We present the results of measurements of optical characteristics of waters (the beam attenuation coefficient, volume scattering function, sea water reflectance, and Secchi depth) and optical characteristics of the atmosphere (aerosol optical thickness, content of vapors, and the Ångström exponent) carried out in September 2008 on the oceanographic platform near Katsiveli. We carried out the comparative analysis of hydrooptical characteristics
New hydro-optical instruments for sub-pixel scale investigation of satellite features and a new t... more New hydro-optical instruments for sub-pixel scale investigation of satellite features and a new technique to invert water properties is described. The new semi-analytic algorithm, based on high resolution spectrally continuous remote sensing reflectance measurements, is proposed for inversion of the optical properties. The algorithm retrieves absorption spectra of phytoplankton pigment and pigment concentration.
We present the results of measurements of optical characteristics of waters (the beam attenuation... more We present the results of measurements of optical characteristics of waters (the beam attenuation coefficient, volume scattering function, sea water reflectance, and Secchi depth) and optical characteristics of the atmosphere (aerosol optical thickness, content of vapors, and the Ångström exponent) carried out in September 2008 on the oceanographic platform near Katsiveli. We carried out the comparative analysis of hydrooptical characteristics
Atmospheric correction of satellite optical data is based on an assessment of the optical charact... more Atmospheric correction of satellite optical data is based on an assessment of the optical characteristics of the atmosphere, such as the aerosol optical depth of the atmosphere and the spectral slope of its spectrum, the so-called Angstrom parameter. Inaccurate determination of these parameters is one of the causes of errors in the retrieval of the remote sensing reflectance spectra. In this work, the obtained large array of field and satellite data for the northeastern part of the Black Sea is used, including ship-based measurements of atmospheric characteristics and sea reflectance, MODIS Aqua/Terra and OLCI Sentinel-3 A/B Level 2 remote sensing reflectance and atmospheric data. The purpose of this study is to show the numerical differences between the atmospheric parameters measured from the surface level and from the satellite and demonstrate their relationship with the differences between in situ and satellite remote sensing reflectance. Based on the information received, we pr...
24th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics, 2018
The first results in development of method for satellite monitoring of the bio-optical water prop... more The first results in development of method for satellite monitoring of the bio-optical water properties of Gorky reservoir as an example of an inland freshwater eutrophic water body are presented. The method is based on the semi-analytical algorithm for the Black Sea and uses the data on the reflectance coefficient of the water column, allowing to calculate the concentrations of optically significant substances (phytoplankton pigments, dissolved organic matter and mineral suspended matter). Field measurements of spectral reflectance were carried out in years 2016 – 2017. Spatial variability of reflectance and factors affecting it were analyzed. Reflectance model used in Black Sea algorithm was adapted to biooptical features of the studied water body. Model calculations of pigment concentration were compared with chlorophyll a content data obtained from water samples analyses. The pigment absorption spectra were calculated, showing the spectral features characteristic of photosynthetic pigments. The ways of further research for algorithm development are determined.
Reflectance spectra were measured in situ in April-May 2019 in the north-eastern part of the Blac... more Reflectance spectra were measured in situ in April-May 2019 in the north-eastern part of the Black Sea, the water color characteristics were calculated. The relationships between effective wavelength of reflectance with other optical characteristics are shown. The absorption, vertical light attenuation, euphotic depth are analyzed taking into account the hydrological parameters of the test polygon. Optical water types of the test polygon were determined.
25th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics, 2019
The results of the sea water hydro-optical characteristics calculation from satellite and contact... more The results of the sea water hydro-optical characteristics calculation from satellite and contact data using a modified bio-optical model are presented. The research of the optical characteristics of sea water during the mass growth of coccolithophore is carried out. The estimates of the coccolith and chlorophyll concentration are obtained.
This paper is devoted to the study of the possibilities of restoring the concentrations of chloro... more This paper is devoted to the study of the possibilities of restoring the concentrations of chlorophyll-a (Chl-a) and total suspended matter (TSM) in fresh waterbodies using the images of Sentinel-2 / MSI of the Gorky reservoir as an example, validated via the high-resolution ground-truth data obtained by fluorescence lidar UFL. This water area in the period of intense chromaticity of cyanobacteria is distinguished by their completely heterogeneous spatial-temporal distribution with scales of patchiness from several tens of meters and high temporal variability. For this reason, direct methods of “spot” measurements in place on water samples in a small part of the reservoir for 3 hours relative to the satellite’s span do not provide us with reliable and statistically proved data. In this regard, the work proposed an original method of high-performance sub-satellite synchronous measurements of the brightness of the water column, concentrations of Chl-a and TSM with a fluorescent lidar ...
This paper presents and discusses the results of optical and biological measurements performed du... more 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...
The paper shows the results of optical measurements carried out during the coccolithophore bloom ... more The paper shows the results of optical measurements carried out during the coccolithophore bloom and the primary bio-optical characteristics obtained. Blooming coccolithophores produce a significant amount of mineral suspension, increasing light scattering and reducing the transparency of water. An increase in the backward scattering leads to an increase in the upwelling radiance and the reflectance coefficient of the sea water. On the base of field and satellite data, the characteristics of coccolithophore bloom in June 2017 in the Black Sea are calculated. A weak relationship between the biological and optical characteristics of the bloom is observed. It is shown that in 2017 the optical properties at the test site were determined not only by coccolithophore suspension, but also by a suspension of terrigenous origin. Suspension concentrations and optical parameters during the bloom are estimated.
The scattering characteristics of suspended matter in seawater obtained during combined processin... more The scattering characteristics of suspended matter in seawater obtained during combined processing of the field measurements data of the light beam attenuation coefficient and the information from satellite ocean-color scanners are presented. The model estimation of particles size composition is made. Percent of fine fraction of the suspension and its spatial distribution are shown to correlate with seasonal changes in hydrology of measurements polygon.
The goal of current investigation was a study of seasonal variability of remote sensing reflectan... more The goal of current investigation was a study of seasonal variability of remote sensing reflectance in the lake part of the Gorky reservoir, characterized by intense bloom of blue-green algae. The basis of this study includes the data of ship measurements of remote sensing reflectance, euphotic zone and chlorophyll a and dissolved organic carbon concentrations, performed from May 14, 2018 to August 27, 2018 in 7 points of the reservoir, two of which are located in shallow areas with a slow current (floodplain area), two - in the channel and the remaining three - in estuaries of three inflowing rivers. The spatial and temporal variability of remote sensing reflectance is analyzed, its variations are calculated, vertical profiles of chlorophyll a and dissolved organic carbon are constructed, variations of euphotic depth are determined and correlation between variations of remote sensing reflectance and concentrations of optically active components is established
The possibilities of chlorophyll a (Chl a) and total suspended matter (TSM) retrieval using Senti... more The possibilities of chlorophyll a (Chl a) and total suspended matter (TSM) retrieval using Sentinel-2/MSI imagery and in situ measurements in the Gorky Reservoir are investigated. This water body is an inland freshwater ecosystem within the territory of the Russian Federation. During the algal bloom period, the optical properties of water are extremely heterogeneous and vary on scales of tens of meters. Additionally, they vary in time under the influence of currents and wind forcing. In this case, the usage of the traditional station-based sampling to describe the state of the reservoir may be uninformative and not rational. Therefore, we proposed an original approach based on simultaneous in situ measurements of the remote sensing reflectance by a single radiometer and the concentration of water constituents by an ultraviolet fluorescence LiDAR from a high-speed gliding motorboat. This approach provided fast data collection including 4087 synchronized LiDAR and radiometric measure...
ABSTRACT A concentration-weighted trajectory method for aerosol source localization based on join... more ABSTRACT A concentration-weighted trajectory method for aerosol source localization based on joint statistical analysis of aerosol column volume concentrations and back-trajectory data was used to estimate the spatial distribution of aerosol sources in the East-European region. The aerosol column volume concentration data measured at five AERONET network sites, Belsk, Minsk, Kyiv, Moldova/Kishinev, and Sevastopol, were used. The geographical areas responsible for increased aerosol content at the monitoring sites were mapped separately for coarse-mode and fine-mode aerosol fractions. The investigated area is located between 42° and 62° N in latitude and between 12° and 50° E in longitude. It was shown that the northeastern territories (in relation to the monitoring stations) give a small contribution to the coarse-mode aerosol content. The events of increased coarse-mode aerosol concentration have been caused by sources in the southeastern regions. On average, the air masses with a large content of coarse-mode aerosol particles were delivered to all stations from regions around Donetsk, Rostov-on-Don, and Kharkiv cities. The fine-mode aerosol fraction originated from areas of Tambov, Voronezh, and Kharkiv cities. The calculated aerosol source regions partly correspond to European Monitoring and Evaluation Programme data for eastern Europe. The cause of difference between calculated regions responsible for increased aerosol content at the monitoring sites and the sources of particle emission according to European Monitoring and Evaluation Programme data are discussed. http://www.tandfonline.com/eprint/j99ACAgV2rNeP7uJ8CAR/full
We present the results of measurements of optical characteristics of waters (the beam attenuation... more We present the results of measurements of optical characteristics of waters (the beam attenuation coefficient, volume scattering function, sea water reflectance, and Secchi depth) and optical characteristics of the atmosphere (aerosol optical thickness, content of vapors, and the Ångström exponent) carried out in September 2008 on the oceanographic platform near Katsiveli. We carried out the comparative analysis of hydrooptical characteristics
New hydro-optical instruments for sub-pixel scale investigation of satellite features and a new t... more New hydro-optical instruments for sub-pixel scale investigation of satellite features and a new technique to invert water properties is described. The new semi-analytic algorithm, based on high resolution spectrally continuous remote sensing reflectance measurements, is proposed for inversion of the optical properties. The algorithm retrieves absorption spectra of phytoplankton pigment and pigment concentration.
We present the results of measurements of optical characteristics of waters (the beam attenuation... more We present the results of measurements of optical characteristics of waters (the beam attenuation coefficient, volume scattering function, sea water reflectance, and Secchi depth) and optical characteristics of the atmosphere (aerosol optical thickness, content of vapors, and the Ångström exponent) carried out in September 2008 on the oceanographic platform near Katsiveli. We carried out the comparative analysis of hydrooptical characteristics
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Papers by Elena Korchemkina