Geomagnetism and Aeronomy最新文献

{"title":"Evaluation of Dynamic Attributes and Variability of Ionospheric Slant Total Electron Content Using NavIC Satellite System","authors":"Raj Gusain,&nbsp;Anurag Vidyarthi,&nbsp;Rishi Prakash,&nbsp;A. K. Shukla","doi":"10.1134/S0016793223600625","DOIUrl":"10.1134/S0016793223600625","url":null,"abstract":"<p>The ionosphere is an inhomogeneous and anisotropic medium in nature. It causes degradation in the performance of positioning through Global Navigation Satellite Systems (GNSS). Generally, the vertical total electron content (VTEC) is used to characterize the ionosphere. The present study can further be used to enhance positional accuracy with a Navigation with Indian Constellation (NavIC) dual-frequency receiver, especially in the Northern region of India where the elevation angle is consistently very low. At such low elevation angles, converting Slant Total Electron Content (STEC) to VTEC and vice versa introduces errors. Therefore, in this study, STEC is used directly instead of VTEC. STEC can be used to analyze dynamic variations in the ionosphere and investigate local and regional ionospheric disturbances. The STEC is dependent on various factors such as solar activity, elevation and azimuth angle of the satellite, seasonal variation etc. Therefore, it is necessary to evaluate the dynamic attributes and variability of STEC to maintain high accuracy in any ionospheric conditions. This research paper focuses on the evaluation of dynamic attributes and variability of Ionospheric Slant Total Electron Content using Navigation with Indian Constellation (NavIC) satellite system. This study utilizes 19 months (from June 2017 to December 2018) dual frequency NavIC data to compute and analyze STEC. The results show a significant effect of satellite elevation angle, azimuth angle, and seasonal STEC variability. The discussion highlights the suitability of NavIC geostationary satellites (PRN3, PRN6, and PRN7) of NavIC for ionospheric studies, space weather applications, and identification of local ionospheric irregularities. The research findings demonstrate the importance of considering dynamic attributes and variability of STEC to model applications for maintaining high accuracy in case of any ionospheric irregularity. Additionally, this research could serve as a reference for future studies in the field of ionospheric-plasmapheric studies and space weather applications using NavIC system.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Autocorrelations of the Wolf Number Cycle Fragments and Solar Half-Cycle Forecast","authors":"S. V. Yakovleva,&nbsp;S. V. Starchenko","doi":"10.1134/S0016793224600577","DOIUrl":"10.1134/S0016793224600577","url":null,"abstract":"<p>Autocorrelations of fragments of the Wolf number series (<i>V</i>2) are considered for 6-year forecasting (solar half-cycle). For physical and optimal reasons, fragments similar to one and half cycles are used. Testing is successfully performed on sufficiently reliable pairs of fragments of the series consisting of a fixed and a time-shifted fragment. A pair is selected for testing if the correlation coefficient is 0.91 or more when its components are combined. The original modification of the fixed fragment and the parts of the series following it are used. Similarly, 6-year forecasts after 2023 are produced from the fragment (2008.5–2023.5), which has correlation coefficients from 0.81 to 0.96 with fragments (1978.5–1993.5), (1901.5–1916.5), (1922.5–1937.5), (1964.5–1979.5), and (1985.5–2000.5). The maximum Wolf number (161 ± 30) is expected in mid-2024.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Trends in Ionospheric Solar Activity Indices","authors":"M. G. Deminov","doi":"10.1134/S0016793224600589","DOIUrl":"10.1134/S0016793224600589","url":null,"abstract":"<p>The article presents the first results of identifying trends in annual average ionospheric indices Δ<i>IG</i>₁₂ and Δ<i>T</i>₁₂, which are obtained after excluding from <i>IG</i>₁₂ and <i>T</i>₁₂ the dependence of these indices on solar activity indices. In this case, solar activity indices are <i>F</i>10 and <i>F</i>30—solar radio emission fluxes at 10.7 and 30 cm. It was found that for the interval of 1957–2023, all analyzed linear trends are negative, i.e., quantities Δ<i>IG</i>₁₂ and Δ<i>T</i>₁₂ decrease over time, and these trends are significant. In absolute value, they are maximum for Δ<i>IG</i>₁₂, taking into account the <i>IG</i>₁₂ dependence on <i>F</i>10₁₂, and minimum for Δ<i>T</i>₁₂, taking into account the <i>T</i>₁₂ dependence on <i>F</i>30₁₂. Account for the nonlinearity of trends shows that, e.g., after 2010, they intensified. Relations are presented that make it possible, based on data from trends of the ionospheric indices (Δ<i>IG</i>₁₂ or Δ<i>T</i>₁₂), to judge the nature of the Δ <i>foF</i>2 trend over a specific point. For this, using the IRI model for <i>foF</i>2, a coefficient was obtained that gives the relationship between the trends of the ionospheric index and Δ <i>foF</i>2 over this point. Comparison with experimental data at mid-latitudes revealed that trends of the ionospheric indices make it possible to correctly determine the sign of the Δ <i>foF</i>2 trend and the general tendency for this trend change, but the calculated value of the trend over a specific point may differ markedly from the experimental data.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of Trends in Various Parameters of the F2 Layer","authors":"A. D. Danilov,&nbsp;A. V. Konstantinova","doi":"10.1134/S001679322460067X","DOIUrl":"10.1134/S001679322460067X","url":null,"abstract":"<p>Estimates of the long-term changes in the ionospheric <i>F</i>2 layer parameters (slab thickness, total electron content, height, and maximal electron concentration) are presented and mutually compared. It is shown that these estimates mutually agree and show that both <i>foF</i>2 and <i>hmF</i>2 have been decreasing in recent decades.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Disturbance of the Electric Field in the D-Region of the Ionosphere with an Increase in Radon Emanation","authors":"V. V. Denisenko,&nbsp;N. V. Bakhmetieva","doi":"10.1134/S0016793224600619","DOIUrl":"10.1134/S0016793224600619","url":null,"abstract":"<p>When radon emanates, the conductivity in surface air increases, which causes variation in the electric field not only in the lower atmosphere, but also in the ionosphere. There have been proposals to use such ionospheric disturbances as earthquake precursors. The ionospheric electric fields are calculated using a quasi-stationary model of an atmospheric conductor including the ionosphere. Earlier, we showed that even with extreme radon emanation, electric field disturbances in the E- and F-regions of the ionosphere are several orders of magnitude smaller than the supposed earthquake precursors and smaller than the fields usually existing there, which are created by other generators. In this paper, we focus on the D-region. In the vertical component of the electric field strength, the main contribution to the D-region comes from the fair-weather field. It is shown that in the D-region, the vertical electric field component over the area of intense radon emanation can double in comparison with the fair-weather field. A detailed spatial pattern of disturbances of electric fields and currents in the atmosphere and ionosphere over the radon emanation region is constructed.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solar Wind Low-Temperature Periods and Forbush Decreases: a Statistical Comparison","authors":"A. A. Melkumyan,&nbsp;N. S. Shlyk,&nbsp;A. V. Belov,&nbsp;M. A. Abunina,&nbsp;A. A. Abunin,&nbsp;V. A. Oleneva,&nbsp;V. G. Yanke","doi":"10.1134/S0016793224600565","DOIUrl":"10.1134/S0016793224600565","url":null,"abstract":"<p>Based on a large amount of experimental material, the hourly values of the solar wind speed and proton temperature were compared; the expected proton temperature and temperature index (the ratio of the observed temperature to the expected one) were calculated. Using the Cosmic Ray Variations Database, from 1997 to 2022 low-temperature periods were identified (intervals lasting more 2 h, in which hourly values of the temperature index less than 0.5). The study investigated (a) statistical relationships between the parameters of low-temperature periods and the characteristics of Forbush decreases associated with different types of solar sources; (b) distributions of parameters of low-temperature periods for interplanetary disturbances containing or not containing a magnetic cloud. The results showed that with increasing duration of the low-temperature period, the proportion of events associated with ejections from active regions increases, while the proportion of recurrent events and events associated with ejections outside active regions decreases. The correlation of the parameters of low-temperature periods with the magnitude of Forbush decreases is weak; with the equatorial anisotropy of cosmic rays, moderate; and with the azimuthal anisotropy, significant. The solar wind speed and magnetic field strength correlate moderately with the temperature index, and the correlation of the range of these parameters with the duration of low-temperature periods is significant or strong.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Method for Forecasting Geomagnetic Storms Based on Deep Learning Neural Networks Using Time Series of Matrix Observations of the Uragan Muon Hodoscope","authors":"V. G. Getmanov,&nbsp;A. D. Gvishiani,&nbsp;A. A. Soloviev,&nbsp;K. S. Zaitsev,&nbsp;M. E. Dunaev,&nbsp;E. V. Yekhlakov","doi":"10.1134/S0016793224600644","DOIUrl":"10.1134/S0016793224600644","url":null,"abstract":"<p>A method for forecasting geomagnetic storms based on deep learning neural networks using digital time series processing for matrix observations of the URAGAN muon hodoscope and scalar <i>Dst</i>-indices has been developed. A scheme of computational operations and extrapolation formulas for matrix observations are proposed. The a variant of the neural network software module and its parameters are chosen. A decision-making rule is formed to forecast and assess the probabilities of correct and false forecasts of geomagnetic storms. An experimental study of estimates of the probabilistic characteristics and forecasting intervals of geomagnetic storms has confirmed the efficiency of the method. The obtained forecasting results are oriented towards solving a number of solar–terrestrial physics and national economic problems.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Use of the Event Matrix for Chorus from the Lower Frequency Band to Determine Some Characteristics of Their Excitation Mechanism","authors":"P. A. Bespalov,&nbsp;O. N. Savina,&nbsp;G. M. Neshchetkin","doi":"10.1134/S0016793224600553","DOIUrl":"10.1134/S0016793224600553","url":null,"abstract":"<p>The article studies quantitative characteristics of the mechanism of excitation of VLF chorus emissions by analyzing high-resolution data from the Van Allen Probes. A typical example of chorus with spectral forms in the lower frequency band (below half of the electron cyclotron frequency) in the region of the local minimum of the magnetic field behind the plasmapause in the middle magnetosphere is presented. A new method of analysis of quasi-harmonic signals recorded with high digitization frequency is proposed and implemented by the example of chorus in the lower frequency band. The results of wave field measurements in a high-resolution data channel are presented in the form of a rectangular event matrix, each row of which corresponds to one cycle of the wave process. In the event matrix, the rows corresponding to the fragments of the implementation that characterize the natural source of short electromagnetic pulses are selected. This made it possible to determine the complex eigenvalues of the characteristic equation of the source at the linear stage of chorus excitation. The values of the roots of the characteristic equation obtained by analyzing the data of chorus observations correspond to the implementation of chorus excitation by the amplification of noise electromagnetic pulses in a planar densification waveguide.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Trends of the Vertical Component of the Wave Activity Flux in the Northern Hemisphere","authors":"K. A. Didenko,&nbsp;T. S. Ermakova,&nbsp;A. V. Koval,&nbsp;E. N. Savenkova","doi":"10.1134/S0016793224600632","DOIUrl":"10.1134/S0016793224600632","url":null,"abstract":"<p>Long-term trends of the three-dimensional Plumb wave activity flux are studied using data from the JRA-55 global atmospheric reanalysis. The vertical component of the Plumb flux characterizes the propagation of atmospheric planetary waves generated in the troposphere to the upper atmosphere and is used for the analysis of the stratosphere–troposphere dynamic interaction. The study of the wave activity flux covers three latitudinal sectors of the Northern Hemisphere from December to March for a 64-year period since 1958. It is shown that in January and March over the Russian Far East there is a statistically significant trend for an increase in the wave activity flux from the troposphere to the stratosphere, which can contribute to an increase in the frequency of cold wave formation in the mid-latitude troposphere. The study of the stratosphere–troposphere dynamic interaction in general and wave activity fluxes in particular is necessary for solving problems related to both global and regional climatic changes and mixing of long-lived atmospheric components.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Models for Short-Term Forecast of Maximum X-ray Class of Solar Flares Based on Magnetic Energy of Active Regions","authors":"I. V. Zimovets,&nbsp;I. N. Sharykin","doi":"10.1134/S0016793224600541","DOIUrl":"10.1134/S0016793224600541","url":null,"abstract":"<p>The accuracy of the M. Aschwanden’s (2020) model for short-term (24 h) prediction of the maximum X-ray class of solar flares based on the power-law dependence on the energy of the potential magnetic field of active regions is checked and assessed. For this purpose, a sample of 275 flares (253 M-class and 22 X-class) in isolated active regions on the solar disk in 2010−2023 is analyzed. Magnetic field extrapolations are made in the nonlinear force-free and potential approximations using the GX Simulator based on photospheric vector magnetograms from the Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory (SDO). It is found that in 6% of cases, Aschwanden’s model underestimates the predicted maximum flare class with respect to the observed one (maximal underestimation by 4.4 times). The accuracy of this model (the average ratio of the observed to predicted maximum flare class) is 0.31 ± 0.47. Four other statistical models are proposed, two of which, like Aschwanden’s model, are based on the power-law dependence of the maximum flare class on the energy of potential magnetic field, and the other two are based on the power-law dependence on the free magnetic energy of active regions. These models give fewer (or no) underestimations of the maximum flare class, but two to three times lower forecast accuracy, ranging from 0.11 to 0.17. Additionally, based on the obtained statistical sample, estimates of the limiting X-ray class of solar flares are made. The five models give different limits ranging from ~X14 to ~X250. The realism of these values and the possibility of refining the models by expanding the sample of events is briefly discussed.</p>","PeriodicalId":55597,"journal":{"name":"Geomagnetism and Aeronomy","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}