Publications
This page highlights a selection of our papers on active and passive sensor developments, showcasing their applications across various types of water bodies
Regional Models for Sentinel-2/MSI Imagery of Chlorophyll a and TSS, Obtained for Oligotrophic Issyk-Kul Lake Using High-Resolution LIF LiDAR Data
Developing regional satellite bio-optical models for variable waters requires an intermediate step for precise measurement of key water quality parameters, such as chlorophyll a (Chl a), CDOM, and TSS. A solution is using laser-induced fluorescence (LIF) via marine LiDAR from a fast-moving vessel, allowing data collection to match satellite overpasses. This method was applied to Issyk-Kul Lake, Kyrgyzstan, yielding over 4000 Chl a and 1000 TSS matchups. Preliminary bio-optical models were created and tested using Sentinel-2A data. This approach can be used for regular monitoring and model adjustments for diverse water bodies.
Pelevin V, Koltsova E, Molkov A, Fedorov S, Alymkulov S, Konovalov B, Alymkulova M, Jumaliev K. Regional Models for Sentinel-2/MSI Imagery of Chlorophyll a and TSS, Obtained for Oligotrophic Issyk-Kul Lake Using High-Resolution LIF LiDAR Data. Remote Sensing. 2023; 15(18):4443. https://doi.org/10.3390/rs15184443
Toward Atmospheric Correction Algorithms for Sentinel-3/OLCI Images of Productive Waters
Atmospheric correction of remote sensing imagery over optically complex waters is still a challenging task. Even algorithms showing a good accuracy for moderate and extremely turbid waters need to be tested when being used for eutrophic inland basins. Such a test was carried out in this study on the example of a Sentinel-3/OLCI image of the productive waters of the Gorky Reservoir during the period of intense blue-green algal bloom using data on the concentration of chlorophyll a and remote sensing reflectance measured from the motorboat at many points of the reservoir. The accuracy of four common atmospheric correction (AC) algorithms was examined. All of them showed unsatisfactory accuracy due to incorrect determination of atmospheric aerosol parameters and aerosol radiance. The calculated aerosol optical depth (AOD) spectra varied widely (AOD(865) = 0.005 − 0.692) even over a small area (up to 10 × 10 km) and correlated with the measured chlorophyll a. As a result, a part of the high water-leaving signal caused by phytoplankton bloom was taken as an atmosphere signal. A significant overestimation of atmospheric aerosol parameters, as a consequence, led to a strong underestimation of the remote sensing reflectance and low accuracy of the considered AC algorithms. To solve this problem, an algorithm with a fixed AOD was proposed. The fixed AOD spectrum was determined in the area with relatively “clean” water as 5 percentiles of AOD in all water pixels. The proposed algorithm made it possible to obtain the remote sensing reflectance with high accuracy. The slopes of linear regression are close to 1 and the intercepts tend to zero in almost all spectral bands. The determination coefficients are more than 0.9; the bias, mean absolute percentage error, and root-mean-square error are notably lower than for other AC algorithms.
Molkov A, Fedorov S, Pelevin V. Toward Atmospheric Correction Algorithms for Sentinel-3/OLCI Images of Productive Waters. Remote Sensing. 2022; 14(15):3663. https://doi.org/10.3390/rs14153663
Regional Models for High-Resolution Retrieval of Chlorophyll a and TSM Concentrations in the Gorky Reservoir by Sentinel-2 Imagery
The study examines the retrieval of chlorophyll a (Chl a) and total suspended matter (TSM) in the Gorky Reservoir using Sentinel-2/MSI imagery and in situ measurements. Due to variable optical properties during algal blooms, traditional sampling is ineffective. An alternative approach combined in situ reflectance measurements and water constituent analysis via LiDAR from a high-speed boat, resulting in 4087 synchronized measurements at an 8 m resolution in two hours. Part of this data matched a Sentinel-2 overpass, aiding in developing regional algorithms for Chl a and TSM retrieval. This first-of-its-kind research in Russia can be applied for regular monitoring and adapted for other reservoirs.
A. Molkov , S. Fedorov, V. Pelevin , E. Korchemkina: Regional Models for High-Resolution Retrieval of Chlorophyll a and TSM Concentrations in the Gorky Reservoir by Sentinel-2 Imagery. Remote Sensing. 2019; 11(10):1215; https://doi.org/10.3390/rs11101215
High resolution LiDAR measurements reveal fine internal structure and variability of sediment-carrying coastal plume
We report results of a field survey conducted in the buoyant, sediment-carrying coastal plume generated by the discharge from the Patos Lagoon, the World's largest choked lagoon. The concentration of total suspended matter (TSM) and organic matter (as represented by total organic carbon, TOC) were mapped using an ultraviolet fluorescent LiDAR, which allowed for extensive data coverage (total of 79,387 simultaneous determinations of TSM and TOC) during 3 consecutive days. These observations were accompanied by hydrographic measurements from the ship and at a mooring station. We first describe synoptic variability of the plume, which responded energetically to wind forcing. We then analyze the TSM, TOC and hydrographic data jointly and develop a simple approach to estimate the rates of suspended matter removal from the upper layer due to gravitational settling and turbulent mixing based on relative changes in TSM and TOC concentrations. Four distinct regions within the plume exhibiting different dynamics of suspended and dissolved constituents were identified on this basis.
Zavialov, P. O., Pelevin, V. V., Belyaev, N. A., Izhitskiy, A. S., Konovalov, B. V., Krementskiy, V. V., Goncharenko, I. V., Osadchiev, A. A., Soloviev, D. M., Garcia, C. A. E., Pereira, E. S., Sartorato, L., and Moller Jr., O. O.: High resolution LiDAR measurements reveal fine internal structure and variability of sediment-carrying coastal plume. Estuarine, Coastal and Shelf Science. 2018; 205, 40–45, https://doi.org/10.1016/j.ecss.2018.01.008
Ground truth data on chlorophyll-a, chromophoric dissolved organic matter and suspended sediment concentrations in the upper water layer as obtained by LIF lidar at high spatial resolution
This article is based on field measurements on the lake Balaton (Hungary) during the three days: 10, 11, and 12 September 2008. The expedition was performed with the aim to test recently developed ultraviolet (UV) fluorescent portable lidar UFL-8 in natural lake waters and to validate it by contact conventional measurements. We had opportunity to compare our results with the Moderate Resolution Imaging Spectroradiometer (MODIS)/Terra spectroradiometer satellite images received at the satellite monitoring station of the Eötvös Loránd University (Budapest, Hungary) to make an attempt of lidar calibration of satellite medium-resolution bands data. Water quality parameters were surveyed with the help of UFL lidar in a time interval very close to the satellite overpass. High resolution maps of the chlorophyll-a, chromophoric dissolved organic matter and total suspended sediments spatial distributions were obtained.
Pelevin V., Zlinszky A., Khimchenko E., Toth V. Ground truth data on chlorophyll-a, chromophoric dissolved organic matter and suspended sediment concentrations in the upper water layer as obtained by LIF lidar at high spatial resolution. International Journal of Remote Sensing. 2017; Vol. 38. No. 7. 1967-1982, http://dx.doi.org/10.1080/01431161.2016.1274446
Structure of the buoyant plume formed by Ob and Yenisei river discharge in the southern part of the Kara Sea during summer and autumn
This article focuses on the interaction between the Ob- and Yenisei-dominated parts of the large Ob-Yenisei buoyant plume formed in the southern part of the Kara Sea during ice-free periods. It was shown that certain wind forcing and river discharge conditions cause the formation of a specific structure of the Ob-Yenisei plume with significantly different properties of the Ob- and Yenisei-dominated water masses. Under these conditions, the Yenisei runoff generates a narrow coastal current propagating northward from the Yenisei Gulf along the Taymyr Peninsula, which is isolated by the Ob-dominated water mass from ambient sea water. As a result, the low-salinity Yenisei-dominated water mass occupies a relatively small area, while more saline Ob-dominated water mass spreads over a wide area between the Gulf of Ob and the Taymyr Peninsula. The formation of the “isolation” configuration of the Ob-Yenisei plume described above is presumed to be caused by the eastward Ekman transport and the resulting downwelling flow of the Ob-dominated waters under the low-saline and warm Yenisei-dominated waters along the Taymyr Peninsula. Based on satellite imagery, wind reanalysis, and river discharge data collected and derived for the period of 2005–2011, it was estimated that the “isolation” configuration is regularly formed during late summer and autumn when the Ob discharge to the Kara Sea exceeds the Yenisei discharge and the local atmospheric circulation is dominated by the northerly wind regime. Assessment of the frequency and duration of the occurrence of the “isolation” configuration showed their synoptic time scale and significant interannual variability.
A.A. Osadchiev A.S. Izhitskiy P.O. Zavialov V.V. Kremenetskiy A.A. Polukhin V.V. Pelevin Z.M. Toktamysova. Structure of the buoyant plume formed by Ob and Yenisei river discharge in the southern part of the Kara Sea during summer and autumn. Journal of Geophysical Research. 2017; Vol. 22, Iss. 7. 5916 - 5935. https://doi.org/10.1002/2016JC012603
Ultraviolet Fluorescence LiDAR (UFL) as a Measurement Tool for Water Quality Parameters in Turbid Lake Conditions
Despite longstanding contributions to oceanography, similar use of fluorescence light detection and ranging (LiDAR) in lake settings is not routine. The potential for ship-mounted, multispectral Ultraviolet Fluorescence LiDAR (UFL) to provide rapid, high-resolution data in variably turbid and productive lake conditions are investigated here through a series of laboratory tank and field measurements carried out on Lake Balaton, Hungary. UFL data, calibrated empirically to a set of coinciding conventionally-analyzed samples, provide simultaneous estimates of three important parameters-chlorophyll a(chla), total suspended matter (TSM) and colored dissolved organic matter (CDOM). Successful UFL retrievals from both laboratory and field measurements were achieved for chla (0.01–378 mg·m−3; R = 0.83–0.92), TSM (0.1–130 g·m−3; R = 0.90–0.96) and CDOM (0.003–0.125 aCDOM(440); R = 0.80–0.97). Fluorescence emission at 685 nm is shown through tank measurements to display robust but distinct relationships with chla concentration for the two cultured algae species investigated (cyanobacteria, Cylindrospermopsis raciborskii, and chlorophyta, Scenedesmus armatus). The ratio between fluorescence emissions measured at 650 nm, related to the phycocyanin fluorescence maximum, to that at 685 nm is demonstrated to effectively distinguish these two species. Validation through both laboratory measurements and field measurements confirmed that site specific calibration is necessary. This study presents the first known assessment and application of ship-mounted fluorescence LiDAR in freshwater lake conditions and demonstrates the use of UFL in measuring important water quality parameters despite the more complicated hydro-optic conditions of inland waters.
Palmer, S.C.; Pelevin, V.V.; Goncharenko, I.; Kovács, A.W.; Zlinszky, A.; Présing, M.; Horváth, H.; Nicolás-Perea, V.; Balzter, H.; Tóth, V.R. Ultraviolet Fluorescence LiDAR (UFL) as a Measurement Tool for Water Quality Parameters in Turbid Lake Conditions. Remote Sensing. 2013; 5, 4405-4422, https://doi.org/10.3390/rs5094405