Pub Date : 2024-03-08DOI: 10.1134/s0010952523700843
O. V. Sapunova, N. L. Borodkova, Yu. I. Yermolaev, G. N. Zastenker
Abstract
The paper investigates the characteristics of the power spectra of fluctuations in the density of protons and α particles near the front of the interplanetary (IP) and Earth’s bow shock (BS). The frequencies of the power spectra break of fluctuations in the density of protons and α particles were calculated before and behind the ramp of the Earth’s bow shock and interplanetary shock. For the disturbed solar wind beyond the IP ramp, the frequency of the spectrum break of proton fluctuations turned out to be noticeably higher (on average 1.3 Hz) than in the undisturbed region (∼0.8–1.0 Hz), which is explained by an increase in both the velocity and the density of particles. In the case of α particles, the frequency of the spectrum break of fluctuations behind the IP front also increased by almost two times (from 0.7 to 0.12 Hz). It is shown that the average value of the frequency of the proton spectra break behind the ramps is less (0.6 Hz) than in the solar wind (1.0 Hz), due to lower velocity. For α particles, this effect was not statistically detected due to an increase in the density (0.11 Hz for both regions) in the case of BS.
{"title":"Spectra of Fluctuations of Solar Wind Plasma Parameters near a Shock Wave","authors":"O. V. Sapunova, N. L. Borodkova, Yu. I. Yermolaev, G. N. Zastenker","doi":"10.1134/s0010952523700843","DOIUrl":"https://doi.org/10.1134/s0010952523700843","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper investigates the characteristics of the power spectra of fluctuations in the density of protons and α particles near the front of the interplanetary (IP) and Earth’s bow shock (BS). The frequencies of the power spectra break of fluctuations in the density of protons and α particles were calculated before and behind the ramp of the Earth’s bow shock and interplanetary shock. For the disturbed solar wind beyond the IP ramp, the frequency of the spectrum break of proton fluctuations turned out to be noticeably higher (on average 1.3 Hz) than in the undisturbed region (∼0.8–1.0 Hz), which is explained by an increase in both the velocity and the density of particles. In the case of α particles, the frequency of the spectrum break of fluctuations behind the IP front also increased by almost two times (from 0.7 to 0.12 Hz). It is shown that the average value of the frequency of the proton spectra break behind the ramps is less (0.6 Hz) than in the solar wind (1.0 Hz), due to lower velocity. For α particles, this effect was not statistically detected due to an increase in the density (0.11 Hz for both regions) in the case of BS.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"19 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-08DOI: 10.1134/s0010952523700788
I. L. Ovchinnikov, D. Yu. Naiko, E. E. Antonova
Abstract
The spectra of fluctuations of electric and magnetic fields in the plasma sheet of the Earth’s magnetotail according to Magnetospheric Multiscale Mission data were statistically analyzed for the years 2017–2022 during periods with small plasma velocity. The results of measurements of the FIELDS instrument suite were considered. Three-hour intervals were identified, during which the satellites were inside the plasma sheet and the plasma parameter β > 1. Over 100 thousand spectra of fluctuations of the electric field by the EDP/DCE instrument and the magnetic field by the FGM instrument were analyzed. Intervals with plasma velocities exceeding 100 km/s were excluded. For each interval, the spectral indices were calculated in the frequency range 0.014–16 Hz. It is shown that the values of the spectral indices differ significantly for the electric and magnetic fields. The dependences of the spectral indices on the fluctuations of the electric and magnetic fields averaged over the interval are obtained.
{"title":"Fluctuations of the Electric and Magnetic Fields in the Plasma Sheet of the Earth’s Magnetotail According to MMS Data","authors":"I. L. Ovchinnikov, D. Yu. Naiko, E. E. Antonova","doi":"10.1134/s0010952523700788","DOIUrl":"https://doi.org/10.1134/s0010952523700788","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The spectra of fluctuations of electric and magnetic fields in the plasma sheet of the Earth’s magnetotail according to Magnetospheric Multiscale Mission data were statistically analyzed for the years 2017–2022 during periods with small plasma velocity. The results of measurements of the FIELDS instrument suite were considered. Three-hour intervals were identified, during which the satellites were inside the plasma sheet and the plasma parameter β > 1. Over 100 thousand spectra of fluctuations of the electric field by the EDP/DCE instrument and the magnetic field by the FGM instrument were analyzed. Intervals with plasma velocities exceeding 100 km/s were excluded. For each interval, the spectral indices were calculated in the frequency range 0.014–16 Hz. It is shown that the values of the spectral indices differ significantly for the electric and magnetic fields. The dependences of the spectral indices on the fluctuations of the electric and magnetic fields averaged over the interval are obtained.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"36 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-08DOI: 10.1134/s0010952523700752
V. I. Kalenova, V. M. Morozov, M. G. Rak
Abstract
The stabilization of regular precessions of a satellite in a circular orbit is considered using control moments determined by Lorentzian forces. The linearized system of equations of motion belongs to a special class of linear time-varying systems that can be reduced to time-invariant ones. Controllability was studied both for the original time-varying systems and on the basis of the reduced time-invariant systems. Optimal stabilization algorithms have been constructed. Mathematical modeling of the proposed algorithms was carried out, confirming the performance and effectiveness of the proposed methodology.
{"title":"Stabilization of Regular Satellite Precessions Using Lorentz Force Moments","authors":"V. I. Kalenova, V. M. Morozov, M. G. Rak","doi":"10.1134/s0010952523700752","DOIUrl":"https://doi.org/10.1134/s0010952523700752","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The stabilization of regular precessions of a satellite in a circular orbit is considered using control moments determined by Lorentzian forces. The linearized system of equations of motion belongs to a special class of linear time-varying systems that can be reduced to time-invariant ones. Controllability was studied both for the original time-varying systems and on the basis of the reduced time-invariant systems. Optimal stabilization algorithms have been constructed. Mathematical modeling of the proposed algorithms was carried out, confirming the performance and effectiveness of the proposed methodology.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"1 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-08DOI: 10.1134/s0010952523600075
Chali Idosa Uga, Sujan Prasad Gautam, Ephrem Beshir Seba
Abstract
This work investigates the relationship between cosmic ray intensity (CRI) and key interplanetary and geomagnetic parameters during both disturbed (November 1–6, 2021) and quiet (November 7–12, 2021) periods. Four neutron monitor stations, namely BKSN, DOMC, JUNG, and MXCO, are employed to analyze the behavior of CRI in response to variations in southward interplanetary magnetic field (IMF Bz), interplanetary electric field (IEF Ey), solar wind speed (Vsw), and geomagnetic indices, including Kp and Dst. During the storm period, time series plots reveal significant Forbush Decreases (FD) in CRI at all stations. These FDs exhibit distinct characteristics, with the most substantial reduction observed at high-latitude stations and the least at low-latitude stations. Notably, the Mexico station, situated in the low-latitude region, records higher neutron counts for both disturbed and quiet periods compared to the middle (BKSN and JUNG) and high-latitude (DOMC) stations. Cross-correlation analysis is employed to examine the relationships between CRI and the aforementioned parameters. Results indicate that during the geomagnetically disturbed period, CRI exhibits negative correlations with IMF Bz, Vsw, and Kp index, while demonstrating positive correlations with Dst and IEF Ey. The strongest correlation is observed between CRI and Dst, suggesting that it can affect variations in cosmic rays measured on Earth, during the geomagnetic storms. In contrast, during the quiet period, significantly weaker correlation was observed than the disturbed period. However, at the JUNG station, CRI displays good correlations with all considered parameters even during the quiet period. The station-specific correlations signifies the importance of geographic location in shaping the response of CRI to external influences.
{"title":"Cross-Correlation Analysis of Cosmic Ray Intensity with Interplanetary and Geomagnetic Parameters during Disturbed and Quiet Periods","authors":"Chali Idosa Uga, Sujan Prasad Gautam, Ephrem Beshir Seba","doi":"10.1134/s0010952523600075","DOIUrl":"https://doi.org/10.1134/s0010952523600075","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This work investigates the relationship between cosmic ray intensity (CRI) and key interplanetary and geomagnetic parameters during both disturbed (November 1–6, 2021) and quiet (November 7–12, 2021) periods. Four neutron monitor stations, namely BKSN, DOMC, JUNG, and MXCO, are employed to analyze the behavior of CRI in response to variations in southward interplanetary magnetic field (IMF <i>Bz</i>), interplanetary electric field (IEF <i>Ey</i>), solar wind speed (<i>Vsw</i>), and geomagnetic indices, including <i>Kp</i> and <i>Dst</i>. During the storm period, time series plots reveal significant Forbush Decreases (FD) in CRI at all stations. These FDs exhibit distinct characteristics, with the most substantial reduction observed at high-latitude stations and the least at low-latitude stations. Notably, the Mexico station, situated in the low-latitude region, records higher neutron counts for both disturbed and quiet periods compared to the middle (BKSN and JUNG) and high-latitude (DOMC) stations. Cross-correlation analysis is employed to examine the relationships between CRI and the aforementioned parameters. Results indicate that during the geomagnetically disturbed period, CRI exhibits negative correlations with IMF <i>Bz</i>, <i>Vsw</i>, and <i>Kp</i> index, while demonstrating positive correlations with <i>Dst</i> and IEF <i>Ey</i>. The strongest correlation is observed between CRI and <i>Dst</i>, suggesting that it can affect variations in cosmic rays measured on Earth, during the geomagnetic storms. In contrast, during the quiet period, significantly weaker correlation was observed than the disturbed period. However, at the JUNG station, CRI displays good correlations with all considered parameters even during the quiet period. The station-specific correlations signifies the importance of geographic location in shaping the response of CRI to external influences.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"132 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-08DOI: 10.1134/s0010952523700831
D. A. Moiseenko, A. Yu. Shestakov, O. L. Vaisberg, R. N. Zhuravlev, M. V. Mityurin, P. P. Moiseev
Article
—This article describes the construction, principles of operating, and characteristics of the TOTEM- electron spectrometer developed for the Strannik complex of scientific instruments for the Resonance-MKA space project. In the article, analytical characteristics are presented of the qualification model of the instrument, which fully corresponds to the flight unit, and the procedure for functional tests of the instrument is described. The article also describes the structure and principles of functioning of the hardware and software laboratory facility developed for ground calibrations and tests of such a type of instruments. The design of the TOTEM-E instrument offers a new approach to measuring particle fluxes, which allows the accuracy and speed of measurements to be increased. A feature of the proposed scheme is the possibility of simultaneous measurement of electron fluxes in a plane section in the velocity space in the energy range from E0 to 6.5 × E0, where E0 is the minimum particle energy recorded by the instrument. This is achieved by using two conical electrostatic mirrors that take electrons from a flat 360° flow section for subsequent energy analysis and using a coordinate-sensitive detector for simultaneous particle registration.
{"title":"The TOTEM-E Electron Spectrometer for the Strannik Space Mission","authors":"D. A. Moiseenko, A. Yu. Shestakov, O. L. Vaisberg, R. N. Zhuravlev, M. V. Mityurin, P. P. Moiseev","doi":"10.1134/s0010952523700831","DOIUrl":"https://doi.org/10.1134/s0010952523700831","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">\u0000<b>Article</b>\u0000</h3><p>—This article describes the construction, principles of operating, and characteristics of the TOTEM- electron spectrometer developed for the Strannik complex of scientific instruments for the <i>Resonance</i>-<i>MKA</i> space project. In the article, analytical characteristics are presented of the qualification model of the instrument, which fully corresponds to the flight unit, and the procedure for functional tests of the instrument is described. The article also describes the structure and principles of functioning of the hardware and software laboratory facility developed for ground calibrations and tests of such a type of instruments. The design of the TOTEM-E instrument offers a new approach to measuring particle fluxes, which allows the accuracy and speed of measurements to be increased. A feature of the proposed scheme is the possibility of simultaneous measurement of electron fluxes in a plane section in the velocity space in the energy range from <i>E</i><sub>0</sub> to 6.5 × <i>E</i><sub>0</sub>, where <i>E</i><sub>0</sub> is the minimum particle energy recorded by the instrument. This is achieved by using two conical electrostatic mirrors that take electrons from a flat 360° flow section for subsequent energy analysis and using a coordinate-sensitive detector for simultaneous particle registration.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"15 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-27DOI: 10.1134/s0010952523700648
A. N. Romanov, I. V. Khvostov, I. V. Ryabinin, D. A. Romanov
Abstract
The climatic changes taking place in Northern Eurasia, which have become especially aggravated in the past few decades, in combination with the anthropogenic impact on ecosystems, are causing noticeable changes in the hydrological characteristics of mineral lakes. Based on the results of daily measurements of brightness temperature Tb from the SMOS (Soil Moisture and Ocean Solution) satellite, the long-term seasonal dynamics of hydrological changes in some large mineral lakes of Northern Eurasia (Caspian Sea, Kara-Bogaz-Gol Bay, Aral Sea, lakes Sarykamyshskoe, Kulunda, Ubsu-Nur) from 2012 to 2022 was studied. The analysis of the seasonal and interannual dynamics of Tb and thermodynamic temperature of the underlying surface was performed on the basis of the SMOS L1C and MODIS MOD11A1 (Moderate Resolution Imaging Spectroradiometer) products, respectively. Four periods were identified with different behavior of the radiative characteristics of mineral lakes, associated with a decrease in temperature below the freezing point of salt water, the formation and melting of ice cover on the water surface, changes in the area of the water table, and salinity of water. In the northern Caspian Sea, the influence of the phenological phases of ice cover on the change in the microwave radiation of the underlying surface was noted. The features of microwave radiation of the western (deep water) and northern parts of the Aral Sea are studied. The seasonal dynamics of Tb is associated with the processes of formation of ice cover on the water surface. Judging by the changed seasonal dynamics of the Tb, the Sarykamysh Lake was transformed into a year-round ice-free lake. Peculiarities of the seasonal dynamics of Tb for Lake Ubsu-Nur are revealed that may be associated with rainfall in the winter–spring season, as well as with the early opening of rivers and flooding of the ice cover of the lake with river water.
{"title":"Analysis of Hydrological Changes in Mineral Lakes in Northern Eurasia Based on SMOS Satellite Data","authors":"A. N. Romanov, I. V. Khvostov, I. V. Ryabinin, D. A. Romanov","doi":"10.1134/s0010952523700648","DOIUrl":"https://doi.org/10.1134/s0010952523700648","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The climatic changes taking place in Northern Eurasia, which have become especially aggravated in the past few decades, in combination with the anthropogenic impact on ecosystems, are causing noticeable changes in the hydrological characteristics of mineral lakes. Based on the results of daily measurements of brightness temperature <i>T</i><sub>b</sub> from the <i>SMOS</i> (Soil Moisture and Ocean Solution) satellite, the long-term seasonal dynamics of hydrological changes in some large mineral lakes of Northern Eurasia (Caspian Sea, Kara-Bogaz-Gol Bay, Aral Sea, lakes Sarykamyshskoe, Kulunda, Ubsu-Nur) from 2012 to 2022 was studied. The analysis of the seasonal and interannual dynamics of <i>T</i><sub>b</sub> and thermodynamic temperature of the underlying surface was performed on the basis of the <i>SMOS</i> L1C and <i>MODIS</i> MOD11A1 (Moderate Resolution Imaging Spectroradiometer) products, respectively. Four periods were identified with different behavior of the radiative characteristics of mineral lakes, associated with a decrease in temperature below the freezing point of salt water, the formation and melting of ice cover on the water surface, changes in the area of the water table, and salinity of water. In the northern Caspian Sea, the influence of the phenological phases of ice cover on the change in the microwave radiation of the underlying surface was noted. The features of microwave radiation of the western (deep water) and northern parts of the Aral Sea are studied. The seasonal dynamics of <i>T</i><sub>b</sub> is associated with the processes of formation of ice cover on the water surface. Judging by the changed seasonal dynamics of the <i>T</i><sub>b</sub>, the Sarykamysh Lake was transformed into a year-round ice-free lake. Peculiarities of the seasonal dynamics of <i>T</i><sub>b</sub> for Lake Ubsu-Nur are revealed that may be associated with rainfall in the winter–spring season, as well as with the early opening of rivers and flooding of the ice cover of the lake with river water.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"71 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140888529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-27DOI: 10.1134/s0010952523700661
E. A. Terekhin
Abstract
The article presents results of analysis of the relationships between forest-stand parameters (age, height, growing stock volume) and Sentinel‑2 spectral reflectance in the Central Russian forest–steppe. The age of oak forests is inversely related to the reflectance in all spectral ranges. The strongest relationship between age and spectral response was found in the red and short wave infrared (SWIR) bands. The relationships between forest age and reflectance in all Sentinel‑2 bands are curvilinear and are most reliably approximated by a logarithmic curve. The height and growing stock volume of oak forests are also in inverse, curvilinear dependence with spectral reflectance in all ranges. The relationship of the height of oak forests with the spectral response is stronger than with the age of the stand. Ash-dominated forests and oak-dominated forests are characterized by similar relationships between age, forest height, and spectral reflectance. For the ages and heights of forests dominated by ash, the strongest relationship with the spectral reflectance values was also found for the Sentinel‑2 SWIR bands.
{"title":"Relationships between Forest-Stand Parameters and Sentinel‑2 Spectral Reflectance in the Central Russian Forest–Steppe","authors":"E. A. Terekhin","doi":"10.1134/s0010952523700661","DOIUrl":"https://doi.org/10.1134/s0010952523700661","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The article presents results of analysis of the relationships between forest-stand parameters (age, height, growing stock volume) and <i>Sentinel‑2</i> spectral reflectance in the Central Russian forest–steppe. The age of oak forests is inversely related to the reflectance in all spectral ranges. The strongest relationship between age and spectral response was found in the red and short wave infrared (SWIR) bands. The relationships between forest age and reflectance in all <i>Sentinel‑2</i> bands are curvilinear and are most reliably approximated by a logarithmic curve. The height and growing stock volume of oak forests are also in inverse, curvilinear dependence with spectral reflectance in all ranges. The relationship of the height of oak forests with the spectral response is stronger than with the age of the stand. Ash-dominated forests and oak-dominated forests are characterized by similar relationships between age, forest height, and spectral reflectance. For the ages and heights of forests dominated by ash, the strongest relationship with the spectral reflectance values was also found for the <i>Sentinel‑2</i> SWIR bands.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"31 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140888730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-27DOI: 10.1134/s0010952523700594
O. Yu. Lavrova, K. R. Nazirova, Ya. O. Alferyeva, D. M. Soloviev, E. V. Zhuk
Abstract
Measurements of Sulak River plume parameters in the Caspian Sea conducted from June 2 to 7, 2023, concurrently with satellite survey allowed tracing changes in water turbidity (WT) and suspended particulate matter (SPM) concentration in the near-mouth zone after the arrival of mudflow masses into the sea. Heavy rains in the mountains of Dagestan on May 31, 2023, caused mudflows, which entered, in particular, the Sulak River. Two days later, on June 2, mud masses, together with river water, flowed into the Caspian Sea. In the near-mouth zone, WT values exceeded 1000 NTU, which was beyond the allowable threshold of a portable turbidimeter employed for turbidity measurements. On June 2, 4, 5 and 7, quasi-synchronously with satellite imaging, measurements were conducted from a small boat using various oceanographic equipment. They were accompanied with water sampling for further determination of SPM concentration and mineral composition. The linear dependence revealed between WT and SPM concentration made it possible to calculate WT that could not be measured in situ: it amounted to 1247 NTU at SPM concentration of 1097.4 g/m3. Satellite data were used to compile WT maps using the Dogliotti 2015 algorithm. The results of satellite observations and in situ measurements showed that, within 2 days, WT and SPM concentration at the nearest to the river mouth station dropped sixfold and continued to decrease to the average values for this area in early June. Determined by X-ray phase analysis, the mineral composition of suspended solids on the day of mudflow arrival into the sea was represented mainly by clay minerals, their content reaching 75%. Later, by June 7, the mineral composition returned to the average values and the content of clay minerals did not exceed 44%.
{"title":"Changes in Sulak River Plume Parameters after Mudflows in the Mountains of Dagestan","authors":"O. Yu. Lavrova, K. R. Nazirova, Ya. O. Alferyeva, D. M. Soloviev, E. V. Zhuk","doi":"10.1134/s0010952523700594","DOIUrl":"https://doi.org/10.1134/s0010952523700594","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Measurements of Sulak River plume parameters in the Caspian Sea conducted from June 2 to 7, 2023, concurrently with satellite survey allowed tracing changes in water turbidity (WT) and suspended particulate matter (SPM) concentration in the near-mouth zone after the arrival of mudflow masses into the sea. Heavy rains in the mountains of Dagestan on May 31, 2023, caused mudflows, which entered, in particular, the Sulak River. Two days later, on June 2, mud masses, together with river water, flowed into the Caspian Sea. In the near-mouth zone, WT values exceeded 1000 NTU, which was beyond the allowable threshold of a portable turbidimeter employed for turbidity measurements. On June 2, 4, 5 and 7, quasi-synchronously with satellite imaging, measurements were conducted from a small boat using various oceanographic equipment. They were accompanied with water sampling for further determination of SPM concentration and mineral composition. The linear dependence revealed between WT and SPM concentration made it possible to calculate WT that could not be measured in situ: it amounted to 1247 NTU at SPM concentration of 1097.4 g/m<sup>3</sup>. Satellite data were used to compile WT maps using the Dogliotti 2015 algorithm. The results of satellite observations and in situ measurements showed that, within 2 days, WT and SPM concentration at the nearest to the river mouth station dropped sixfold and continued to decrease to the average values for this area in early June. Determined by X-ray phase analysis, the mineral composition of suspended solids on the day of mudflow arrival into the sea was represented mainly by clay minerals, their content reaching 75%. Later, by June 7, the mineral composition returned to the average values and the content of clay minerals did not exceed 44%.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"11 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139979927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-27DOI: 10.1134/s0010952523700521
A. I. Aleksanin, A. N. Timofeev
Abstract
The problem of calculating the normalized vegetation index (NDVI) from satellite data is considered. The index values calculated from the MODIS/Aqua radiometer data by the SeaDAS software package algorithm are compared with the values obtained at the La Crau research site (France) for 7 years. The site is located near the Mediterranean coast and is a flat field where grass grows. The measurements are carried out by the ROSAS automatic photometric station. Calculations show the proximity of satellite and field measurements: bias of 0.005 and standard deviation of 0.03. The algorithm used does not take into account the effect of aerosol on the NDVI value. However, the errors due to the lack of accounting for aerosol lie within the limits of the total calculation error. There is a slight dependence of the error on the zenith angle of the sun, which varied in the range from 20° to 70°. The bidirectional reflectance distribution function of the surface on the site is uniform, except for the directions close to the sunbeam. The measurements were far from the sunbeam zone. However, the accuracy of the calculation depends on the difference between the azimuth angle of the site survey and the azimuth to the sun. NDVI mismatches due to differences in the central wave numbers of different satellites also turned out to be significant. The comparison was made for the following radiometers: MODIS/Aqua, Landsat-8/OLI-1, Landsat-9/OLI-2, and Kanopus-V/MSS.
{"title":"The Influence of Observation Conditions on the Accuracy of NDVI Vegetation Index Calculation from Earth Remote Sensing Data","authors":"A. I. Aleksanin, A. N. Timofeev","doi":"10.1134/s0010952523700521","DOIUrl":"https://doi.org/10.1134/s0010952523700521","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The problem of calculating the normalized vegetation index (NDVI) from satellite data is considered. The index values calculated from the MODIS/<i>Aqua</i> radiometer data by the SeaDAS software package algorithm are compared with the values obtained at the La Crau research site (France) for 7 years. The site is located near the Mediterranean coast and is a flat field where grass grows. The measurements are carried out by the ROSAS automatic photometric station. Calculations show the proximity of satellite and field measurements: bias of 0.005 and standard deviation of 0.03. The algorithm used does not take into account the effect of aerosol on the NDVI value. However, the errors due to the lack of accounting for aerosol lie within the limits of the total calculation error. There is a slight dependence of the error on the zenith angle of the sun, which varied in the range from 20° to 70°. The bidirectional reflectance distribution function of the surface on the site is uniform, except for the directions close to the sunbeam. The measurements were far from the sunbeam zone. However, the accuracy of the calculation depends on the difference between the azimuth angle of the site survey and the azimuth to the sun. NDVI mismatches due to differences in the central wave numbers of different satellites also turned out to be significant. The comparison was made for the following radiometers: MODIS/<i>Aqua</i>, <i>Landsat-8</i>/OLI-1, <i>Landsat-9</i>/OLI-2, and <i>Kanopus-V</i>/MSS.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"42 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139980045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-27DOI: 10.1134/s001095252370065x
R. Kh. Tembotov
Abstract
Based on the information obtained on organic carbon content in soils and remote sensing data, a mapping model reflecting the spatial variation of organic carbon content in the upper horizons (0–20 cm) of soils in Central Caucasus was created using digital soil modelling and mapping technology. For modelling we applied a multifunctional approach involving a combination of actual data on the organic carbon content (training set) with data derived from external sources of information (remote sensing data) that was processed using a stepwise discriminant analysis. The necessity of creating a model of organic carbon distribution in soils separately for artificial (agrocenoses) and natural biogeocenoses was established using statistical methods of analysis. As a result of combining two hypothetical models, a verified model reflecting the real picture of changes in the organic carbon content in soils of Central Caucasus was obtained. The reliability of the model was 68%. It contains actual data on organic carbon content in natural and agrogenic soils of Central Caucasus. This model is a necessary tool for making decisions to maintain or increase current soil carbon stocks under conditions of climate change and increasing anthropogenic impact.
{"title":"Using a Multifunctional Approach for Cartographic Modeling of Organic Carbon Content in Natural and Arable Soils of the Central Caucasus","authors":"R. Kh. Tembotov","doi":"10.1134/s001095252370065x","DOIUrl":"https://doi.org/10.1134/s001095252370065x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Based on the information obtained on organic carbon content in soils and remote sensing data, a mapping model reflecting the spatial variation of organic carbon content in the upper horizons (0–20 cm) of soils in Central Caucasus was created using digital soil modelling and mapping technology. For modelling we applied a multifunctional approach involving a combination of actual data on the organic carbon content (training set) with data derived from external sources of information (remote sensing data) that was processed using a stepwise discriminant analysis. The necessity of creating a model of organic carbon distribution in soils separately for artificial (agrocenoses) and natural biogeocenoses was established using statistical methods of analysis. As a result of combining two hypothetical models, a verified model reflecting the real picture of changes in the organic carbon content in soils of Central Caucasus was obtained. The reliability of the model was 68%. It contains actual data on organic carbon content in natural and agrogenic soils of Central Caucasus. This model is a necessary tool for making decisions to maintain or increase current soil carbon stocks under conditions of climate change and increasing anthropogenic impact.</p>","PeriodicalId":56319,"journal":{"name":"Cosmic Research","volume":"20 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140889911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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