@article{MTMT:34605575, title = {Regional Models for Sentinel-2/MSI Imagery of Chlorophyll a and TSS, Obtained for Oligotrophic Issyk-Kul Lake Using High-Resolution LIF LiDAR Data}, url = {https://m2.mtmt.hu/api/publication/34605575}, author = {Pelevin, Vadim and Koltsova, Ekaterina and Molkov, Aleksandr and Fedorov, Sergei and Alymkulov, Salmor and Konovalov, Boris and Alymkulova, Mairam and Jumaliev, Kubanychbek}, doi = {10.3390/rs15184443}, journal-iso = {REMOTE SENS-BASEL}, journal = {REMOTE SENSING}, volume = {15}, unique-id = {34605575}, abstract = {The development of regional satellite bio-optical models for natural waters with high temporal and spatial variability, such as inland seas, reservoirs, and coastal ocean waters, requires the implementation of an intermediate measuring link in the chain, "water sampling-bio-optical models", and this link must have certain intermediate characteristics. The most crucial of them are the high-precision measurements of the main water quality parameters, such as the concentration of chlorophyll a (Chl a), colored dissolved organic matter (CDOM), and total suspended sediments (TSS) in the upper water layer, together with a high operational rate and the ability to cover a large water area in a short time, which corresponds to a satellite overpass. A possible solution is to utilize laser-induced fluorescence (LIF) of water constituents measured by a marine LiDAR in situ with a high sampling rate from a high-speed vessel. This allows obtaining a large ground-truth dataset of the main water quality parameters simultaneously with the satellite overpass within the time interval determined by NASA protocols. This method was successfully applied to the oligotrophic Issyk-Kul Lake in Kyrgyzstan, where we obtained more than 4000 and 1000 matchups for the Chl a and TSS, respectively. New preliminary regional bio-optical models were developed on the basis of a one-day survey and tested for archive Sentinel-2A data for 2022. This approach can be applied for regular monitoring and further correction in accordance with seasonal variability. The obtained results, together with previously published similar studies for eutrophic coastal and productive inland waters, emphasize the applicability of the presented method for the development or adjustment of regional bio-optical models for water bodies of a wide trophic range.}, keywords = {LIDAR; CHLOROPHYLL; LIF; SENTINEL; TSS; Ocean color; bio-optical models; Issyk-Kul Lake}, year = {2023}, eissn = {2072-4292}, orcid-numbers = {Molkov, Aleksandr/0000-0002-8550-2418; Fedorov, Sergei/0000-0001-7716-7456} } @article{MTMT:34605576, title = {Sensing profiles of the volume scattering function at 180° using a single-photon oceanic fluorescence lidar}, url = {https://m2.mtmt.hu/api/publication/34605576}, author = {Shangguan, Mingjia and Guo, Yirui and Liao, Zhuoyang and Lee, Zhongping}, doi = {10.1364/OE.505615}, journal-iso = {OPT EXPRESS}, journal = {OPTICS EXPRESS}, volume = {31}, unique-id = {34605576}, issn = {1094-4087}, abstract = {A novel oceanic fluorescence lidar technique has been proposed and demonstrated for remotely sensing the volume scattering function at 180 degrees (beta f), which can be used to further retrieve the profiles of the absorption coefficient of phytoplankton (aph) at 532 nm and chlorophyll concentration (Chl). This scheme has these features. 1) The single-photon detection technology is employed to enhance the detection sensitivity to the single-photon level, enabling the oceanic lidar to obtain fluorescence backscatter profiles. 2) In terms of algorithms, the Raman backscattered signals of the water are utilized to normalize the backscattered signals of chlorophyll fluorescence, effectively minimizing the depth-dependent variation of the differential lidar attenuation coefficient lidar). To reduce the contamination of fluorescence signals in the Raman backscatter signals, a Raman filter with a bandwidth of 6 nm was chosen. Subsequently, a perturbation method is utilized to invert the beta f of the fluorescence lidar. Finally, aph and Chl profiles can be inverted based on empirical models. 3) The value of increment Kfr semi-analytic Monte Carlo simulation. According to theoretical analysis, the maximum relative error of beta f for Chl ranging from 0.01 mg/m3 to 10 mg/m3 is less than 13 %. To validate this approach, a field experiment was conducted aboard the R/V Tan Kah Kee in the South China Sea from September 4th to September 5th, 2022, resulting in continuous subsurface profiles of beta f, aph, and Chl. These measurements confirm the robustness and reliability of the oceanic single-photon fluorescence lidar system and the inversion algorithm.}, year = {2023}, pages = {40393-40410} } @article{MTMT:33886117, title = {Dissolved Organic Matter of the Surface Water Layer of Gelendzhik Bay in September 2021 According to Fluorimetry and Lidar Measurements}, url = {https://m2.mtmt.hu/api/publication/33886117}, author = {Drozdova, A. N. and Pelevin, V. V. and Krylov, I. N. and Streltsova, E. A. and Konovalov, B. V.}, doi = {10.1134/S0001437022060030}, journal-iso = {OCEANOLOGY+}, journal = {OCEANOLOGY}, volume = {62}, unique-id = {33886117}, issn = {0001-4370}, abstract = {We present the results of optical studies of organic matter in the surface water layer of Gelendzhik Bay and adjacent areas of the Black Sea. The efficiency of remote laser sensing for determining the relevant grid of sampling stations is shown. A weak contribution of terrigenous dissolved organic matter (DOM) has been established. A slight increase in the concentration of humic substances was demonstrated near the mouth of the Su-Aran River. The maximal content of biolabile DOM is typical for coastal regions in Gelendzhik Bay. In the eastern part of the bay high levels of DOM, particulate organic matter (POM), as well as the maximum content of DOM and POM together, were observed on the basis of fluorescent lidar data.}, keywords = {FLUORESCENCE; Black sea; dissolved organic matter; particulate organic matter; fluorescent LiDAR; Gelendzhik Bay}, year = {2022}, eissn = {1531-8508}, pages = {765-772} } @article{MTMT:33911677, title = {YAG:Nd3+ Laser Systems for Marine UV Lidar}, url = {https://m2.mtmt.hu/api/publication/33911677}, author = {Lyashenko, A. I. and Volodina, E. M. and Gol'din, Yu. A. and Gureev, B. A.}, doi = {10.1134/S1064226922120154}, journal-iso = {J COMMUN TECHNOL EL+}, journal = {JOURNAL OF COMMUNICATIONS TECHNOLOGY AND ELECTRONICS}, volume = {67}, unique-id = {33911677}, issn = {1064-2269}, abstract = {It is shown that lidar sounding of the aquatic environment by laser radiation at a wavelength of 266 nm provides high sensitivity and reliability of detection of petroleum products. For use in marine lidars, two YAG:Nd3+ laser systems (laser-amplifier) with radiation conversion into the fourth harmonic (with lamp and diode pumping) are proposed.}, year = {2022}, eissn = {1555-6557}, pages = {1475-1478} } @article{MTMT:33218282, title = {Toward Atmospheric Correction Algorithms for Sentinel-3/OLCI Images of Productive Waters}, url = {https://m2.mtmt.hu/api/publication/33218282}, author = {Molkov, Aleksandr and Fedorov, Sergei and Pelevin, Vadim}, doi = {10.3390/rs14153663}, journal-iso = {REMOTE SENS-BASEL}, journal = {REMOTE SENSING}, volume = {14}, unique-id = {33218282}, abstract = {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 x 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.}, keywords = {VALIDATION; LAKE; satellite imagery; chlorophyll a; Inland waters; Gorky reservoir; LIF LiDAR; UFL-9; Sentinel-3; atmospheric correction algorithms; ocean optics; non-station-based in situ measurements; productive waters}, year = {2022}, eissn = {2072-4292}, orcid-numbers = {Molkov, Aleksandr/0000-0002-8550-2418; Fedorov, Sergei/0000-0001-7716-7456} } @article{MTMT:33369185, title = {Pathways of carbonate sediment accumulation in a large, shallow lake}, url = {https://m2.mtmt.hu/api/publication/33369185}, author = {Rostási, Ágnes and Rácz, Kornél and Fodor, Melinda and Topa, Boglárka Anna and Molnár, Zsombor and Weiszburg, Tamás and Pósfai, Mihály}, doi = {10.3389/feart.2022.1067105}, journal-iso = {FRONT EARTH SC-SWITZ}, journal = {FRONTIERS IN EARTH SCIENCE}, volume = {10}, unique-id = {33369185}, abstract = {Since carbonate formation is an important process linking inorganic and biological components of freshwater ecosystems, we characterized the formation of modern carbonate sediments in a large, shallow, calcareous lake (Lake Balaton in Hungary). We measured the amount of allochtonous mineral particles delivered to the lake by tributaries and through the atmosphere over a 2-year period, and estimated the mass of carbonate minerals that precipitated from lakewater. Chemical and structural features of mineral particles from various sources were also studied. Both the mineralogical character and the amount of particles delivered by streams and through the atmosphere were similar, and formed a minor fraction of the annual sediment increment (∼5%–6% by mass). Since the watercourses feeding the lake had high concentrations of Ca2+, Mg2+, and HCO3− (with a Mg/Ca mol ratio ranging from 1 to 4), Mg-bearing calcite (with 2–17 mol% MgCO3) was found to continually precipitate in the lake. According to X-ray powder diffraction measurements, the Mg content of calcite increased from West to East, in parallel with changes in water chemistry. Dolomite was detected as a minor phase, and in the eastern part of the lake it typically produced a split 104 peak in X-ray diffractograms, suggesting two distinct sources: stoichiometric dolomite was allochtonous, whereas a Ca-rich protodolomite fraction formed in the lake. Mg-bearing calcite precipitating in the lake was found by far the largest contributor to sediment formation, with an estimated annual accumulation of about 0.75–0.9 mm consolidated sediment; thus, ∼89% of the currently forming sediment consists of autochtonous carbonate. In addition to providing new estimates for the rates of accumulation of distinct sediment fractions, our results also provide a baseline for further studies on the retention and release of nutrients by sediment minerals.}, year = {2022}, eissn = {2296-6463}, orcid-numbers = {Rostási, Ágnes/0000-0002-0269-390X; Rácz, Kornél/0000-0003-3091-9205; Topa, Boglárka Anna/0000-0003-1996-2261; Molnár, Zsombor/0000-0002-9836-3488; Weiszburg, Tamás/0000-0001-8183-4434; Pósfai, Mihály/0000-0001-9355-3533} } @article{MTMT:33330274, title = {Bio-optical studies on chlorophyll-a concentration in Hooghly River, India}, url = {https://m2.mtmt.hu/api/publication/33330274}, author = {Premkumar, R. and Venkatachalapathy, R. and Visweswaran, S.}, doi = {10.1016/j.matpr.2021.05.034}, journal-iso = {MATER TOD PROC}, journal = {MATERIALS TODAY: PROCEEDINGS}, volume = {47}, unique-id = {33330274}, issn = {2214-7853}, abstract = {The concentration of chlorophyll-a in the aquatic environment is a good indicator to understand its tropic status and also used to monitor the biogeochemical parameter. The aim of this study is to identify the spectral signature of Hooghly River, India using Satlantic hyperspectral ocean colour radiometer and developing the regional algorithm for retrieval for chlorophyll-a concentration. This approach is based on the development of an empirical band ratio algorithm. The calibrated results between the in-situ chlorophyll-a and in-situ remote sensing reflectance show a good correlation with R2 = 0.77. In-situ and satellite validation also gives better accuracy (R2 = 0.78&0.73) in the estimation of chlorophyll-a concentration. So the satellite-based approach provides a good correlation with in-situ data. This study was helped in monitoring and retrieval of chl-a concentration in the Hooghly River, Kolkata. (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 12th National Conference on Recent Advancements in Biomedical Engineering.}, keywords = {Total suspended matter; Hyperspectral radiometer; Regional algorithm; Sentinel 2 MSI data; Hooghly river}, year = {2021}, pages = {488-492} } @article{MTMT:32167732, title = {Adaptation and Validation of a Sentinel-Based Chlorophyll-a Retrieval Software for the Central European Freshwater Lake, Balaton}, url = {https://m2.mtmt.hu/api/publication/32167732}, author = {Tóth, Veronika Zsófia and Ladányi, Márta and Jung, András}, doi = {10.1007/s41064-021-00160-1}, journal-iso = {PFG-J PHOTOGRAMM REM}, journal = {PFG-JOURNAL OF PHOTOGRAMMETRY REMOTE SENSING AND GEOINFORMATION SCIENCE}, volume = {89}, unique-id = {32167732}, issn = {2512-2789}, year = {2021}, eissn = {2512-2819}, pages = {335-344}, orcid-numbers = {Tóth, Veronika Zsófia/0000-0002-5339-191X; Ladányi, Márta/0000-0003-3114-8289; Jung, András/0000-0003-3250-4097} } @article{MTMT:31101792, title = {Lidar Monitoring of Chlorophyll a During the XXIX and XXXI Italian Antarctic Expeditions}, url = {https://m2.mtmt.hu/api/publication/31101792}, author = {Fiorani, Luca and Angelini, Federico and Artuso, Florinda and Cataldi, Dario and Colao, Francesco}, doi = {10.1007/s41742-019-00169-w}, journal-iso = {INT J ENVIRON RES}, journal = {INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH}, volume = {13}, unique-id = {31101792}, issn = {1735-6865}, abstract = {Although it is known that the Ross Sea is responsible for more than a quarter of CO2 absorption of the Southern Ocean, more information is needed to model the primary production of this key area. In particular, it is necessary to improve the characterization of the size class distribution, biomass and taxonomic composition of phytoplankton in the Ross Sea. Recently, an innovative compact lidar fluorosensor was deployed for real-time sensing of chlorophyll a, during the Ross Sea Mesoscale Experiment (RoME), conducted in the XXIX (2014) and XXXI (2016) Italian Antarctic expeditions. Furthermore, high-performance liquid chromatography (HPLC) was also performed to provide pigment analysis of in situ samples. Lidar fluorosensors are laser-induced fluorescence (LIF) instruments and have been extensively operated by the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) since the 1990s to monitor water bodies. Spectra obtained with LIF contain signatures of phytoplankton pigments, chromophoric dissolved organic matter and dispersed impurities, such as crude oils. The study of algal pigments provides not only the phytoplankton biomassdirectly linked to chlorophyll abut also its taxonomic composition through detection of several accessory pigments. Moreover, some models allow the identification of phytoplankton size classes. Lidar and HPLC mapped the spatiotemporal distribution of algal biomass and showed that during RoME, the phytoplankton assemblage structure was dominated by large-size cells (micro-phytoplankton) and the prevailing algal groups were diatoms. Article HighlightsLidar fluorosensors provide fast measurements of phytoplankton pigmentsThey are the missing link between satellite radiometers and in situ instrumentsHigh performance liquid chromatography integrates lidar fluorosensorsPhytoplankton spatiotemporal distribution was mapped in the Ross Sea (Antarctica)Phytoplankton functional types and size classes were retrieved}, keywords = {HPLC; LIDAR; CHLOROPHYLL; coastal monitoring; Ross Sea (Antarctica)}, year = {2019}, eissn = {2008-2304}, pages = {253-263}, orcid-numbers = {Fiorani, Luca/0000-0001-9696-3124} } @article{MTMT:30966617, title = {Regional Models for High-Resolution Retrieval of Chlorophyll a and TSM Concentrations in the Gorky Reservoir by Sentinel-2 Imagery}, url = {https://m2.mtmt.hu/api/publication/30966617}, author = {Molkov, Alexander A. and Fedorov, Sergei V. and Pelevin, Vadim V. and Korchemkina, Elena N.}, doi = {10.3390/rs11101215}, journal-iso = {REMOTE SENS-BASEL}, journal = {REMOTE SENSING}, volume = {11}, unique-id = {30966617}, abstract = {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 measurements with high spatial resolutions of 8 m for two hours. A part of the dataset was coincided with Sentinel-2 overpass and used for the development of regional algorithms for the retrieval of Chl a and TSM concentrations. For inland waters of the Russian Federation, such research was performed for the first time. The proposed algorithms can be used for regular environmental monitoring of the Gorky Reservoir using ship measurements or Sentinel-2 images. Additionally, they can be adapted for neighboring reservoirs, for example, for other seven reservoirs on the Volga River. Moreover, the proposed ship measurement approach can be useful in the practice of limnological monitoring of inland freshwater ecosystems with high spatiotemporal variability of the optical properties.}, keywords = {Lakes; inland water; chlorophyll a; Sentinel-2; TSM; Gorky reservoir; high-resolution imagery; ACOLITE; LIF LiDAR; UFL-9; bio-optical properties of water}, year = {2019}, eissn = {2072-4292} } @{MTMT:31577470, title = {Ultraviolet fluorescence lidar (UFL) as a high-resolution measurement tool for water quality parameters, used as ground-truth data for Sentinel-2 regional models}, url = {https://m2.mtmt.hu/api/publication/31577470}, author = {Pelevin, Vadim and Molkov, Aleksandr and Fedorov, Sergei and Korchemkina, Elena}, booktitle = {REMOTE SENSING OF THE OCEAN, SEA ICE, COASTAL WATERS, AND LARGE WATER REGIONS 2019}, doi = {10.1117/12.2533323}, unique-id = {31577470}, abstract = {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 onboard a high-speed vessel. This technique is provided with a spatial (8 m) and a temporary (1 s) resolution. Based on this, 4 independent regional models for the recovery of Chl-a concentrations, as well as TSM were developed based on in-situ measurements of the brightness of the water surface, or from Sentinel-2 / MSI images. To ensure the possibility of using satellite images, the analysis of atmospheric correction algorithms was performed and the best one was determined. The proposed models can be used for regular environmental monitoring of the Gorky Reservoir according to the in-situ ship measurements of the brightness of the water surface or from Sentinel-2 / MSI images. When using the proposed methodology for lidar high-performance collection of sub-satellite data, the developed models can be adapted for limnological monitoring of other freshwater bodies with high spatial and temporal variability of the optical properties of water.}, keywords = {SENTINEL; Fluorescence LiDAR; water quality parameters; UFL; ground-truth data}, year = {2019}, orcid-numbers = {Pelevin, Vadim/0000-0001-6016-8970} } @article{MTMT:30433183, title = {Fluorescence quantum yield of CDOM in coastal zones of the Arctic seas}, url = {https://m2.mtmt.hu/api/publication/30433183}, author = {Drozdova, Anastasia N. and Kravchishina, Marina D. and Khundzhua, Daria A. and Freidkin, Mihail P. and Patsaeva, Svetlana V.}, doi = {10.1080/01431161.2018.1506187}, journal-iso = {INT J REMOTE SENS}, journal = {INTERNATIONAL JOURNAL OF REMOTE SENSING}, volume = {39}, unique-id = {30433183}, issn = {0143-1161}, abstract = {Along with traditional optical indices, calculated from absorption and fluorescence spectra to describe chromophoric dissolved organic matter (CDOM) naturally occurring in water, the fluorescence quantum yield (FQY) becomes significant. Knowledge of CDOM optical properties is important for satellite remote sensing as well as for lidar ground-true measurements. The FQY as a function of excitation wavelength within 240-500 nm range for a variety of the Arctic shelf waters was determined for the first time in order to identify the characteristic chromophores peculiar to different regions of the Arctic basin affected by freshwater runoff. The surface water samples were collected during several cruises in 2015-2017 in the following sites: the mouth areas of the Khatanga and Lena Rivers (the Laptev Sea), the delta area of the Northern Dvina River (the White Sea), desalinated waters of the Kara Sea (influenced by freshwater of the Ob and Yenisei Rivers) and the East Siberian Sea (influenced by freshwaters of the Indigirka and Kolyma Rivers), as well the shelf areas of those seas not affected by terrigenous runoff. To characterize DOM, conventional optical indices SR, HIX, and BIX were calculated. In most cases, important humic character of DOM was established, while the contribution of autochthonous organic matter varied from low to intermediate level. For the samples with terrestrial impact, the FQY decreased from excitation at 240 nm to 270-280 nm and then increased, demonstrating two peaks at 340 and 380 nm, with constant decrease towards longer excitation wavelengths; at lambda(ex) = 380 nm FQY varied from 1.4% to 3.1%. In some cases, additional maximum at 270 nm of FQY-excitation dependency was observed as an indicator of autochthonous nature of biological material. Minimal FQY was measured for the White Sea surface waters, the maximal for the Laptev and East Siberian seas.}, keywords = {PERFORMANCE LIQUID-CHROMATOGRAPHY; OPTICAL-PROPERTIES; remote sensing; humic substances; DISSOLVED ORGANIC-MATTER; Aquatic environments; ELECTROPHORETIC FRACTIONS; ONLINE ABSORBENCY; EASTERN PART; KARA SEA}, year = {2018}, eissn = {1366-5901}, pages = {9356-9379} } @article{MTMT:30433185, title = {New profiling and mooring records help to assess variability of Lake Issyk-Kul and reveal unknown features of its thermohaline structure}, url = {https://m2.mtmt.hu/api/publication/30433185}, author = {Zavialov, Peter O. and Izhitskiy, Alexander S. and Kirillin, Georgiy B. and Khan, Valentina M. and Konovalov, Boris V. and Makkaveev, Peter N. and Pelevin, Vadim V. and Rimskiy-Korsakov, Nikolay A. and Alymkulov, Salmor A. and Zhumaliev, Kubanychbek M.}, doi = {10.5194/hess-22-6279-2018}, journal-iso = {HYDROL EARTH SYST SC}, journal = {HYDROLOGY AND EARTH SYSTEM SCIENCES}, volume = {22}, unique-id = {30433185}, issn = {1027-5606}, abstract = {This article reports the results of three field campaigns conducted in Lake Issyk-Kul in 2015, 2016, and 2017. During the campaigns, CTD profiling and water sampling were performed at 34 locations all over the lake. A total of 75 CTD profiles were obtained. Some biogeochemical and thermohaline parameters at the lake surface were also mapped at high horizontal resolution along the ship's track. In addition, thermistor chains were deployed at three mooring stations in the eastern littoral region of the lake, yielding 147-day-long records of temperature data. The measurements revealed that - while the thermal state of the active layer, as well as some biogeochemical characteristics, were subject to significant interannual variability mediated by atmospheric forcing - the haline structure of the entire lake was remarkably stable at the interannual scale. Our data do not confirm the reports of progressive warming of the deep Issyk-Kul waters as suggested in some previous publications. However, they do indicate a positive trend of salinity in the lake's interior over the last 3 decades. A noteworthy newly found feature is a weak but persistent salinity maximum below the thermocline at a depth of 70-120 m, from where salinity slightly decreased downwards. The data from the moored thermistor chains support the previously published hypothesis about the significant role of the submerged ancient riverbeds on the eastern shelf in advecting littoral waters into the deep portion of the lake during differential cooling period. We hypothesize that the less saline littoral water penetrating into the deep layers due to this mechanism is responsible for the above-mentioned features of salinity profile, and we substantiate this hypothesis by estimates based on simple model assumptions.}, keywords = {Geosciences, Multidisciplinary; DEEP-WATER RENEWAL}, year = {2018}, eissn = {1607-7938}, pages = {6279-6295}, orcid-numbers = {Izhitskiy, Alexander S./0000-0001-6156-6460} } @article{MTMT:27607252, title = {High resolution LiDAR measurements reveal fine internal structure and variability of sediment-carrying coastal plume}, url = {https://m2.mtmt.hu/api/publication/27607252}, author = {Zavialov, P O and Pelevin, V V and Belyaev, N A and Izhitskiy, A S and Konovalov, B V and Krementskiy, V V and Goncharenko, I V and Osadchiev, A A and Soloviev, D M and Garcia, C A E and Pereira, E S and Sartorato, L and Moller, O O Jr}, doi = {10.1016/j.ecss.2018.01.008}, journal-iso = {ESTUAR COAST SHELF S}, journal = {ESTUARINE COASTAL AND SHELF SCIENCE}, volume = {205}, unique-id = {27607252}, issn = {0272-7714}, year = {2018}, eissn = {1096-0015}, pages = {40-45} } @article{MTMT:30439439, title = {Spectroscopic Study of Green Sulfur Bacteria in Stratified Water Bodies of the Kandalaksha Gulf of the White Sea}, url = {https://m2.mtmt.hu/api/publication/30439439}, author = {Zhiltsova, A. A. and Kharcheva, A. V. and Krasnova, E. D. and Lunina, O. N. and Voronov, D. A. and Savvichev, A. S. and Gorshkova, O. M. and Patsaeva, S. V.}, doi = {10.1134/S1024856018040188}, journal-iso = {OPTIK ATM OKEAN}, journal = {OPTIKA ATMOSFERY I OKEANA}, volume = {31}, unique-id = {30439439}, issn = {0869-5695}, abstract = {Optical characteristics of water in stratified lakes of the White Sea are of particular interest in connection with the observation of thin colored layers resulting from massive development of anoxygenic phototrophic bacteria around the chemocline. While optical properties of chlorophyll are widely used in remote sensing, spectral characteristics of bacteriochlorophylls (BChl) for natural microbial communities have been little studied. In this work, spectral study of green sulfur bacteria of four water bodies of the Kandalaksha Gulf of the White Sea was carried out. Absorption and fluorescence spectra were measured for water samples taken in March 2017 from different depths and compared with spectra of monocultures isolated from the same water bodies earlier. It has been shown that the BChl fluorescence in the living cells of green sulfur bacteria has two overlapping emission bands: in the region of 740-770 nm (BChl d and e) and at 815 nm (BChl a). The wavelength of the maximum of the first band depends on the ratio of the concentrations of green- and brown-colored forms of bacteria containing different types of BChl. A new method for separating the contributions of two types of bacteria is proposed, based on the deconvolution of the BChl fluorescence spectrum into three bands whose parameters are determined from the spectra of monocultures. The BChl content at various water depths has been estimated and the percentage ratio of different types of phototrophic bacteria has been determined.}, keywords = {ABSORPTION; FLUORESCENCE; BACTERIOCHLOROPHYLL; Photosynthetic bacteria; CHLOROPHYLL-A; Green sulfur bacteria; anoxygenic phototrophic bacteria}, year = {2018}, eissn = {2949-1630}, pages = {390-396} } @article{MTMT:27141746, title = {European Remote Sensing: progress, challenges, and opportunities}, url = {https://m2.mtmt.hu/api/publication/27141746}, author = {Ban, Yifang and Marullo, Salvatore and Eklundh, Lars}, doi = {10.1080/01431161.2017.1291484}, journal-iso = {INT J REMOTE SENS}, journal = {INTERNATIONAL JOURNAL OF REMOTE SENSING}, volume = {38}, unique-id = {27141746}, issn = {0143-1161}, year = {2017}, eissn = {1366-5901}, pages = {1759-1764}, orcid-numbers = {Eklundh, Lars/0000-0001-7644-6517} } @article{MTMT:27141745, title = {Structure of the buoyant plume formed by Ob and Yenisei river discharge in the southern part of the Kara Sea during summer and autumn}, url = {https://m2.mtmt.hu/api/publication/27141745}, author = {Osadchiev, A A and Izhitskiy, A S and Zavialov, P O and Kremenetskiy, V V and Polukhin, A A and Pelevin, V V and Toktamysova, Z M}, doi = {10.1002/2016JC012603}, journal-iso = {J GEOPHYS RES OCEANS}, journal = {JOURNAL OF GEOPHYSICAL RESEARCH: OCEANS}, volume = {122}, unique-id = {27141745}, issn = {2169-9275}, year = {2017}, eissn = {2169-9291}, pages = {5916-5935} }