The numerical forecast methods used to predict ionospheric convective plasma instabilities associated with Equatorial Spread-F (ESF) have limited accuracy and are often computationally expensive. We test whether it is possible to bypass first-principle numeric simulations and forecast irregularities using machine learning models. The data are obtained from the incoherent scatter radar at the Jicamarca Radio Observatory located in Lima, Peru. Our models map vertical plasma drifts, time, and solar activity to the occurrence and location of clusters of echoes telltale of ionospheric irregularities. Our results show that these models are capable of identifying the predictive power of the tested inputs, obtaining accuracies around 75%.
{"title":"Predicting Equatorial Ionospheric Convective Instability Using Machine Learning","authors":"D. Garcia, E. L. Rojas, D. L. Hysell","doi":"10.1029/2023sw003505","DOIUrl":"https://doi.org/10.1029/2023sw003505","url":null,"abstract":"The numerical forecast methods used to predict ionospheric convective plasma instabilities associated with Equatorial Spread-<i>F</i> (ESF) have limited accuracy and are often computationally expensive. We test whether it is possible to bypass first-principle numeric simulations and forecast irregularities using machine learning models. The data are obtained from the incoherent scatter radar at the Jicamarca Radio Observatory located in Lima, Peru. Our models map vertical plasma drifts, time, and solar activity to the occurrence and location of clusters of echoes telltale of ionospheric irregularities. Our results show that these models are capable of identifying the predictive power of the tested inputs, obtaining accuracies around 75%.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"10 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138529465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We model the electron density in the topside of the ionosphere with an improved machine learning (ML) model and compare it to existing empirical models, specifically the International Reference Ionosphere (IRI) and the Empirical‐Canadian High Arctic Ionospheric Model (E‐CHAIM). In prior work, an artificial neural network (NN) was developed and trained on two solar cycles worth of Defense Meteorological Satellite Program data (113 satellite‐years), along with global drivers and indices to predict topside electron density. In this paper, we highlight improvements made to this NN, and present a detailed comparison of the new model to E‐CHAIM and IRI as a function of location, geomagnetic condition, time of year, and solar local time. We discuss precision and accuracy metrics to better understand model strengths and weaknesses. The updated neural network shows improved mid‐latitude performance with absolute errors lower than the IRI by 2.5 × 109 to 2.5 × 1010 e−/m3, modestly improved performance in disturbed geomagnetic conditions with absolute errors reduced by about 2.5 × 109 e−/m3 at high Kp compared to the IRI, and high Kp percentage errors reduced by >50% when compared to E‐CHAIM.
我们用改进的机器学习（ML）模型来模拟电离层顶部的电子密度，并将其与现有的经验模型，特别是国际参考电离层（IRI）和经验-加拿大北极高电离层模型（E-CHAIM）进行比较。在之前的工作中，我们开发了一个人工神经网络（NN），并根据两个太阳周期的国防气象卫星计划数据（113 个卫星年）以及全球驱动因素和指数对其进行了训练，以预测顶部电子密度。在本文中，我们将重点介绍对 NN 所做的改进，并详细比较新模型与 E-CHAIM 和 IRI 在位置、地磁条件、年度时间和太阳当地时间方面的函数关系。我们讨论了精度和准确度指标，以更好地了解模型的优缺点。更新后的神经网络改善了中纬度的性能，绝对误差比 IRI 低 2.5 × 109 到 2.5 × 1010 e-/m3，在干扰地磁条件下的性能略有改善，与 IRI 相比，在高 Kp 时绝对误差减少了约 2.5 × 109 e-/m3，与 E-CHAIM 相比，高 Kp 百分比误差减少了 >50%。
{"title":"Topside Electron Density Modeling Using Neural Network and Empirical Model Predictions","authors":"S. Dutta, M. Cohen","doi":"10.1029/2023sw003501","DOIUrl":"https://doi.org/10.1029/2023sw003501","url":null,"abstract":"We model the electron density in the topside of the ionosphere with an improved machine learning (ML) model and compare it to existing empirical models, specifically the International Reference Ionosphere (IRI) and the Empirical‐Canadian High Arctic Ionospheric Model (E‐CHAIM). In prior work, an artificial neural network (NN) was developed and trained on two solar cycles worth of Defense Meteorological Satellite Program data (113 satellite‐years), along with global drivers and indices to predict topside electron density. In this paper, we highlight improvements made to this NN, and present a detailed comparison of the new model to E‐CHAIM and IRI as a function of location, geomagnetic condition, time of year, and solar local time. We discuss precision and accuracy metrics to better understand model strengths and weaknesses. The updated neural network shows improved mid‐latitude performance with absolute errors lower than the IRI by 2.5 × 109 to 2.5 × 1010 e−/m3, modestly improved performance in disturbed geomagnetic conditions with absolute errors reduced by about 2.5 × 109 e−/m3 at high Kp compared to the IRI, and high Kp percentage errors reduced by >50% when compared to E‐CHAIM.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"210 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139022210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to achieve more accurate spatial reconstruction of ionospheric total electron content (TEC) and promote improved satellite positioning and ranging applications, a high accuracy spatial reconstruction (HASR) method for TEC is proposed based on the surface theory. The core theory of this method is as follows: (a) Any surface can be uniquely determined by its first and second fundamental quantities; (b) By direct difference approximation, differential equations are transformed into algebraic equations to solve Gauss equations faster. At the same time, taking parts of Europe as an example, the proposed HASR method is used to determine the correlation coefficients and the number of iterations of the model by using the relative root mean square error (RRMSE) as the evaluation criterion. The statistical results show that the TEC predicted by the HASR method is highly consistent with the actual observed values of ionospheric observation stations, and the prediction RRMSE is 9.75%. Compared with the Kriging interpolation with scale factor, the prediction accuracy of the HASR method is improved by 8.5%. We hope this method can provide ideas for the spatial reconstruction of other ionospheric parameters and further promote the realization of complete and accurate space weather forecast.
{"title":"A High Accuracy Spatial Reconstruction Method Based on Surface Theory for Regional Ionospheric TEC Prediction","authors":"Jian Wang, Yi‐ran Liu, Yanmei Shi","doi":"10.1029/2023sw003663","DOIUrl":"https://doi.org/10.1029/2023sw003663","url":null,"abstract":"In order to achieve more accurate spatial reconstruction of ionospheric total electron content (TEC) and promote improved satellite positioning and ranging applications, a high accuracy spatial reconstruction (HASR) method for TEC is proposed based on the surface theory. The core theory of this method is as follows: (a) Any surface can be uniquely determined by its first and second fundamental quantities; (b) By direct difference approximation, differential equations are transformed into algebraic equations to solve Gauss equations faster. At the same time, taking parts of Europe as an example, the proposed HASR method is used to determine the correlation coefficients and the number of iterations of the model by using the relative root mean square error (RRMSE) as the evaluation criterion. The statistical results show that the TEC predicted by the HASR method is highly consistent with the actual observed values of ionospheric observation stations, and the prediction RRMSE is 9.75%. Compared with the Kriging interpolation with scale factor, the prediction accuracy of the HASR method is improved by 8.5%. We hope this method can provide ideas for the spatial reconstruction of other ionospheric parameters and further promote the realization of complete and accurate space weather forecast.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"68 ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138988779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. H. Mac Manus, C. J. Rodger, A. Renton, J. Ronald, D. Harper, C. Taylor, M. Dalzell, T. Divett, M. A. Clilverd
Reducing the impact of Geomagnetically induced currents (GICs) on electrical power networks is an essential step to protect network assets and maintain reliable power transmission during and after storm events. In this study, multiple mitigation strategies are tested during worst-case extreme storm scenarios in order to investigate their effectiveness for the New Zealand transmission network. By working directly with our industry partners, Transpower New Zealand Ltd, a mitigation strategy in the form of targeted line disconnections has been developed. This mitigation strategy proved more effective than previous strategies at reducing GIC magnitudes and durations at transformers at most risk to GIC while still maintaining the continuous supply of power throughout New Zealand. Under this mitigation plan, the average 60-min mean GIC decreased for 27 of the top 30 at-risk transformers, and the total network GIC was reduced by 16%. This updated mitigation has been adopted as an operational procedure in the New Zealand national control room to manage GIC. In addition, simulations show that the installation of 14 capacitor blocking devices at specific transformers reduces the total GIC sum in the network by an additional 16%. As a result of this study Transpower is considering further mitigation in the form of capacitor blockers. We strongly recommend collaborating with the relevant power network providers to develop effective mitigation strategies that reduce GIC and have a minimal impact on power distribution.
{"title":"Geomagnetically Induced Current Mitigation in New Zealand: Operational Mitigation Method Development With Industry Input","authors":"D. H. Mac Manus, C. J. Rodger, A. Renton, J. Ronald, D. Harper, C. Taylor, M. Dalzell, T. Divett, M. A. Clilverd","doi":"10.1029/2023sw003533","DOIUrl":"https://doi.org/10.1029/2023sw003533","url":null,"abstract":"Reducing the impact of Geomagnetically induced currents (GICs) on electrical power networks is an essential step to protect network assets and maintain reliable power transmission during and after storm events. In this study, multiple mitigation strategies are tested during worst-case extreme storm scenarios in order to investigate their effectiveness for the New Zealand transmission network. By working directly with our industry partners, Transpower New Zealand Ltd, a mitigation strategy in the form of targeted line disconnections has been developed. This mitigation strategy proved more effective than previous strategies at reducing GIC magnitudes and durations at transformers at most risk to GIC while still maintaining the continuous supply of power throughout New Zealand. Under this mitigation plan, the average 60-min mean GIC decreased for 27 of the top 30 at-risk transformers, and the total network GIC was reduced by 16%. This updated mitigation has been adopted as an operational procedure in the New Zealand national control room to manage GIC. In addition, simulations show that the installation of 14 capacitor blocking devices at specific transformers reduces the total GIC sum in the network by an additional 16%. As a result of this study Transpower is considering further mitigation in the form of capacitor blockers. We strongly recommend collaborating with the relevant power network providers to develop effective mitigation strategies that reduce GIC and have a minimal impact on power distribution.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"32 5 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138529464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By performing a global magnetohydrodynamic (MHD) simulation, we investigated magnetic disturbances on the ground at high-latitudes in response to jumps in the solar wind dynamic pressure, namely a sudden commencement (SC). After the arrival of the jump, a pair of field-aligned currents (FACs), related to the preliminary impulse, develop and travel in the anti-sunward direction. Soon after another pair related to the main impulse (MI) appears and travels in the anti-sunward direction. The horizontal ionospheric current associated with the MI remains strong when propagating to the nightside. On the dawnside the MI current flows sunward (anti-sunward) resulting in northward (southward) ground magnetic disturbance at higher (lower) latitude in the post-midnight sector. These features are similar to those observed in Canada in the high-latitude post-midnight sector when the Québec blackout took place on 13 March 1989. The nighttime geomagnetic perturbations associated with the MI occur regardless of the magnitude of the solar wind dynamic pressure and IMF orientation. The amplitude of the geoelectric field, which is closely related to the geomagnetically induced currents (GICs), reaches the maximum value just before and around the maximum of the southward magnetic disturbance. This is consistent with the moment at which the blackout occurred during the southward magnetic perturbation. We suggest that the blackout in Québec could be caused by the MI-associated Hall current passing over the Hydro-Québec power system on the nightside. The nighttime polar region is shown to be sensitive to hazardous GICs for large-amplitude jumps in the solar wind dynamic pressure.
{"title":"Nighttime Geomagnetic Response to Jumps of Solar Wind Dynamic Pressure: A Possible Cause of Québec Blackout in March 1989","authors":"T. Zhang, Y. Ebihara, T. Tanaka","doi":"10.1029/2023sw003493","DOIUrl":"https://doi.org/10.1029/2023sw003493","url":null,"abstract":"By performing a global magnetohydrodynamic (MHD) simulation, we investigated magnetic disturbances on the ground at high-latitudes in response to jumps in the solar wind dynamic pressure, namely a sudden commencement (SC). After the arrival of the jump, a pair of field-aligned currents (FACs), related to the preliminary impulse, develop and travel in the anti-sunward direction. Soon after another pair related to the main impulse (MI) appears and travels in the anti-sunward direction. The horizontal ionospheric current associated with the MI remains strong when propagating to the nightside. On the dawnside the MI current flows sunward (anti-sunward) resulting in northward (southward) ground magnetic disturbance at higher (lower) latitude in the post-midnight sector. These features are similar to those observed in Canada in the high-latitude post-midnight sector when the Québec blackout took place on 13 March 1989. The nighttime geomagnetic perturbations associated with the MI occur regardless of the magnitude of the solar wind dynamic pressure and IMF orientation. The amplitude of the geoelectric field, which is closely related to the geomagnetically induced currents (GICs), reaches the maximum value just before and around the maximum of the southward magnetic disturbance. This is consistent with the moment at which the blackout occurred during the southward magnetic perturbation. We suggest that the blackout in Québec could be caused by the MI-associated Hall current passing over the Hydro-Québec power system on the nightside. The nighttime polar region is shown to be sensitive to hazardous GICs for large-amplitude jumps in the solar wind dynamic pressure.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"19 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138529456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alok Kuman Ranjan, M. V. Sunil Krishna, C. Amory-Mazaudier, R. Fleury, S. Sripathi, Geeta Vichare, W. Younas
This paper highlights the impact of intense solar events over India during 3–20 December 2006. Ionospheric effects of a major solar flare (X9) on December 5 (10:35 UT) have been investigated by using dayside and nightside magnetometer data, dayside ionosondes, and dayside GPS vTEC observations. On the next day, a stream of fast solar wind hits the magnetosphere, causing a HILDCAA (High Intensity Long Duration Continuous Auroral Activity) preceded by moderate geomagnetic storm. The origin and characteristics of a positive ionospheric storm which occurred over Tirunelveli (TIR, geomagnetic latitude: −0.18°N) in the recovery phase of storm due to simultaneous presence of enhanced O/N2 and WEJ or weakened EEJ during the HILDCAA (7th and 8th of December) is investigated. Subsequently, on December 14, the most powerful CME since the Halloween event impacts the Earth, and three SSCs are recorded on December 14, 16, and 18. The variability of the ionosphere over the Indian longitude sector due to these intense space weather fluctuations is presented by utilizing the magnetometers, ionosonde, GPS vTEC, and satellite-based observations in the same region. This study reports the influence of prompt penetration of the magnetospheric convection electric field and the disturbance dynamo on several key ionospheric and magnetic parameters within the Indian longitude sector.
{"title":"Variability of Ionosphere Over Indian Longitudes to a Variety of Space Weather Events During December 2006","authors":"Alok Kuman Ranjan, M. V. Sunil Krishna, C. Amory-Mazaudier, R. Fleury, S. Sripathi, Geeta Vichare, W. Younas","doi":"10.1029/2023sw003595","DOIUrl":"https://doi.org/10.1029/2023sw003595","url":null,"abstract":"This paper highlights the impact of intense solar events over India during 3–20 December 2006. Ionospheric effects of a major solar flare (X9) on December 5 (10:35 UT) have been investigated by using dayside and nightside magnetometer data, dayside ionosondes, and dayside GPS vTEC observations. On the next day, a stream of fast solar wind hits the magnetosphere, causing a HILDCAA (High Intensity Long Duration Continuous Auroral Activity) preceded by moderate geomagnetic storm. The origin and characteristics of a positive ionospheric storm which occurred over Tirunelveli (TIR, geomagnetic latitude: −0.18°N) in the recovery phase of storm due to simultaneous presence of enhanced O/N<sub>2</sub> and WEJ or weakened EEJ during the HILDCAA (7th and 8th of December) is investigated. Subsequently, on December 14, the most powerful CME since the Halloween event impacts the Earth, and three SSCs are recorded on December 14, 16, and 18. The variability of the ionosphere over the Indian longitude sector due to these intense space weather fluctuations is presented by utilizing the magnetometers, ionosonde, GPS vTEC, and satellite-based observations in the same region. This study reports the influence of prompt penetration of the magnetospheric convection electric field and the disturbance dynamo on several key ionospheric and magnetic parameters within the Indian longitude sector.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"7 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138529457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Ingham, K. Pratscher, W. Heise, E. Bertrand, M. Kruglyakov, C. J. Rodger
As part of a 5-year project to assess the risk posed by geomagnetically induced currents (GIC) to the New Zealand electrical transmission network, long-period magnetotelluric (MT) measurements have been made at 62 sites in southern South Island of New Zealand, a region where there was an absence of previous MT data. The data are largely 3-dimensional in character, but show distinct features that can be related to the known tectonic and geological structure. In this work we focus on how the measured MT impedance tensors, and a simple interpretation of conductivity structure, can be used to assess the influence of tectonic and geological structure on GIC. We use the impedance tensors to calculate the magnitudes and orientations of induced electric fields in response to various orientations of inducing magnetic field. The electric fields so calculated are then used in a simplified model of the transmission network to calculate GIC at grounded substations. Our results confirm that tectonic/geological structure in the lower South Island and the resulting electrical conductivity variations have important impacts on the GIC magnitude. In the south-west, smaller induced electric fields, associated with the higher conductivity in that region, lead to much reduced GIC at a substation in that area. In contrast, higher electric fields occurring in a NW-SE band across the center of the region, contribute to much larger GIC in Dunedin city. Our results thus help explain the observed GIC reported at transformers in the region.
{"title":"Influence of Tectonic and Geological Structure on GIC in Southern South Island, New Zealand","authors":"M. Ingham, K. Pratscher, W. Heise, E. Bertrand, M. Kruglyakov, C. J. Rodger","doi":"10.1029/2023sw003550","DOIUrl":"https://doi.org/10.1029/2023sw003550","url":null,"abstract":"As part of a 5-year project to assess the risk posed by geomagnetically induced currents (GIC) to the New Zealand electrical transmission network, long-period magnetotelluric (MT) measurements have been made at 62 sites in southern South Island of New Zealand, a region where there was an absence of previous MT data. The data are largely 3-dimensional in character, but show distinct features that can be related to the known tectonic and geological structure. In this work we focus on how the measured MT impedance tensors, and a simple interpretation of conductivity structure, can be used to assess the influence of tectonic and geological structure on GIC. We use the impedance tensors to calculate the magnitudes and orientations of induced electric fields in response to various orientations of inducing magnetic field. The electric fields so calculated are then used in a simplified model of the transmission network to calculate GIC at grounded substations. Our results confirm that tectonic/geological structure in the lower South Island and the resulting electrical conductivity variations have important impacts on the GIC magnitude. In the south-west, smaller induced electric fields, associated with the higher conductivity in that region, lead to much reduced GIC at a substation in that area. In contrast, higher electric fields occurring in a NW-SE band across the center of the region, contribute to much larger GIC in Dunedin city. Our results thus help explain the observed GIC reported at transformers in the region.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"125 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138529452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anomalous long-distance propagation of Very High Frequency radio waves of aeronautical navigation systems was investigated by an airborne Instrument Landing System (ILS) localizer (ILS LOC) receiver installed on the ground at Kure, Japan (34.245°N, 132.528°E). Intense ILS LOC type signals were observed and the received power was strong enough for the aviation receiver to output course deviation. The radio source was identified by receiving the Morse Code for identification as the localizer-type directional aid (LDA) serving the Runway-21 of the Hualien Airport, Taiwan (24.0396°N, 121.6221°E) of which beam pointed close to the receiver. This result supports that the source of the signals often observed at the same frequency at the same location is most probably the LDA at the Hualien Airport. The maximum received power was −99 dBm for an omni-directional antenna. It was strong enough to cause co-channel interference. Considering stronger power (−70 dBm) found in previous observations at the same frequency at the same location, anomalous propagation of ILS LOC signals by the Es layer could be a cause of interference when a receiver was near the center of the ILS LOC beam. The course deviation output was consistent with the geometry between the beam of Runway-21 LDA at the Hualien Airport and the receiver. However, the observed course deviation fluctuated remarkably even when the received power was strong enough. The fluctuation of the course deviation may indicate the structure of the Es layer, and observation of the course deviation could be used to diagnose the Es layer structure.
{"title":"Anomalous Long-Distance Propagation of ILS LOC Signals by the Es Layer and Its Impact on Aviation Receivers","authors":"S. Saito, K. Hosokawa, J. Sakai, I. Tomizawa","doi":"10.1029/2023sw003577","DOIUrl":"https://doi.org/10.1029/2023sw003577","url":null,"abstract":"Anomalous long-distance propagation of Very High Frequency radio waves of aeronautical navigation systems was investigated by an airborne Instrument Landing System (ILS) localizer (ILS LOC) receiver installed on the ground at Kure, Japan (34.245°N, 132.528°E). Intense ILS LOC type signals were observed and the received power was strong enough for the aviation receiver to output course deviation. The radio source was identified by receiving the Morse Code for identification as the localizer-type directional aid (LDA) serving the Runway-21 of the Hualien Airport, Taiwan (24.0396°N, 121.6221°E) of which beam pointed close to the receiver. This result supports that the source of the signals often observed at the same frequency at the same location is most probably the LDA at the Hualien Airport. The maximum received power was −99 dBm for an omni-directional antenna. It was strong enough to cause co-channel interference. Considering stronger power (−70 dBm) found in previous observations at the same frequency at the same location, anomalous propagation of ILS LOC signals by the Es layer could be a cause of interference when a receiver was near the center of the ILS LOC beam. The course deviation output was consistent with the geometry between the beam of Runway-21 LDA at the Hualien Airport and the receiver. However, the observed course deviation fluctuated remarkably even when the received power was strong enough. The fluctuation of the course deviation may indicate the structure of the Es layer, and observation of the course deviation could be used to diagnose the Es layer structure.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"24 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138529463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. R. Smith, D. Ozturk, P. Delamere, G. Lu, H. Kim
Sudden changes in energy input from the magnetosphere during geomagnetic storms could drive extreme variability in the ionosphere‐thermosphere system, which in turn affect satellite operations and other modern infrastructure. Joule heating is the main form of magnetospheric energy dissipation in the ionosphere‐thermosphere system, so it is important to know when and where Joule heating will occur. While Joule heating occurs all the time, it can increase rapidly during geomagnetic storms. We investigated the Joule heating profile of the 2013 St Patrick's day storm using the University of Michigan Global Ionosphere‐Thermosphere Model (GITM). Using empirical and data‐assimilated drivers we analyzed when and where intense Joule heating occurred. The timing, location, and sources of interhemispheric asymmetry during this geomagnetic storm are of key interest due to near equinox conditions. Hemispheric comparisons are made between parameters, including solar insolation, total electron content profiles, and Pedersen and Hall conductance profiles, obtained from GITM driven with empirical driven input, versus those driven with data‐assimilated patterns. Further comparisons are made during periods of peak hemispheric Joule heating asymmetry in an effort to investigate their potential sources. Additionally, we compare the consistency of the interhemispheric asymmetry between empirical‐ and data‐assimilated driven simulations to further analyze the role of data‐assimilated drivers on the IT system.
{"title":"Investigating the Interhemispheric Asymmetry in Joule Heating During the 2013 St. Patrick's Day Geomagnetic Storm","authors":"A. R. Smith, D. Ozturk, P. Delamere, G. Lu, H. Kim","doi":"10.1029/2023SW003523","DOIUrl":"https://doi.org/10.1029/2023SW003523","url":null,"abstract":"Sudden changes in energy input from the magnetosphere during geomagnetic storms could drive extreme variability in the ionosphere‐thermosphere system, which in turn affect satellite operations and other modern infrastructure. Joule heating is the main form of magnetospheric energy dissipation in the ionosphere‐thermosphere system, so it is important to know when and where Joule heating will occur. While Joule heating occurs all the time, it can increase rapidly during geomagnetic storms. We investigated the Joule heating profile of the 2013 St Patrick's day storm using the University of Michigan Global Ionosphere‐Thermosphere Model (GITM). Using empirical and data‐assimilated drivers we analyzed when and where intense Joule heating occurred. The timing, location, and sources of interhemispheric asymmetry during this geomagnetic storm are of key interest due to near equinox conditions. Hemispheric comparisons are made between parameters, including solar insolation, total electron content profiles, and Pedersen and Hall conductance profiles, obtained from GITM driven with empirical driven input, versus those driven with data‐assimilated patterns. Further comparisons are made during periods of peak hemispheric Joule heating asymmetry in an effort to investigate their potential sources. Additionally, we compare the consistency of the interhemispheric asymmetry between empirical‐ and data‐assimilated driven simulations to further analyze the role of data‐assimilated drivers on the IT system.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"29 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87906079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. S. Chingarandi, C. Candido, F. Becker-Guedes, O. F. Jonah, S. P. Moraes‐Santos, V. Klausner, O. O. Taiwo
This paper investigates the effects of a minor G1 Co‐rotating Interaction Region (CIR)/High‐Speed Stream (HSS)‐driven geomagnetic storm that occurred on (13–14 October 2018), during deep solar minimum. We used simultaneous observations from multiple instruments, namely; ground‐based Global Navigation Satellite Systems (GNSS) receivers, a Digisonde, ground magnetometers, and space‐based observations from the National Aeronautics and Space Administration Global‐scale Observations of Limb and Disk (GOLD) and SWARM missions. This study presents a detailed picture of the low‐latitude ionosphere response over the Brazilian sector during a minor storm. Our results showed that the minor CIR/HSS‐driven storm caused a positive ionospheric storm of over ∼20 TECU in magnitude. For the first time, periodic post‐sunset irregularities and Equatorial Plasma Bubbles, equatorial plasma bubbles, were analyzed using GOLD FUV OI 135.6 nm emission, Total Electron Content (TEC) maps, Rate of TEC index, ROTI, and TEC gradients. Fluctuations in the interplanetary magnetic field Bz and changes in the thermospheric column density ratio (∑O/N2) are discussed as the main sources of ionospheric changes during the storm. This paper highlights the importance of monitoring and understanding the impact of Sun‐Earth interactions and provides insight into the behavior of the low‐latitude ionosphere during minor geomagnetic storms.
本文研究了发生在2018年10月13日至14日的一次小型G1共旋转相互作用区(CIR)/高速流(HSS)驱动的地磁风暴对太阳深度极小期的影响。我们使用多个仪器同时观测，即;地面全球导航卫星系统(GNSS)接收机、地面地面仪、地面磁力计，以及来自美国国家航空航天局全球尺度翼盘观测(GOLD)和SWARM任务的天基观测。本研究详细描述了巴西地区低纬度电离层在小型风暴期间的响应情况。我们的研究结果表明，较小的CIR/HSS驱动的风暴引起了一个大于~ 20 TECU量级的电离层正风暴。首次使用GOLD FUV OI 135.6 nm发射、总电子含量(TEC)图、TEC指数率、ROTI和TEC梯度分析了周期性日落后不规则性和赤道等离子体气泡。讨论了行星际磁场Bz的波动和热层柱密度比(∑O/N2)的变化是风暴期间电离层变化的主要来源。本文强调了监测和理解太阳-地球相互作用影响的重要性，并提供了对小型地磁风暴期间低纬度电离层行为的见解。
{"title":"Assessing the Effects of a Minor CIR‐HSS Geomagnetic Storm on the Brazilian Low‐Latitude Ionosphere: Ground and Space‐Based Observations","authors":"F. S. Chingarandi, C. Candido, F. Becker-Guedes, O. F. Jonah, S. P. Moraes‐Santos, V. Klausner, O. O. Taiwo","doi":"10.1029/2023SW003500","DOIUrl":"https://doi.org/10.1029/2023SW003500","url":null,"abstract":"This paper investigates the effects of a minor G1 Co‐rotating Interaction Region (CIR)/High‐Speed Stream (HSS)‐driven geomagnetic storm that occurred on (13–14 October 2018), during deep solar minimum. We used simultaneous observations from multiple instruments, namely; ground‐based Global Navigation Satellite Systems (GNSS) receivers, a Digisonde, ground magnetometers, and space‐based observations from the National Aeronautics and Space Administration Global‐scale Observations of Limb and Disk (GOLD) and SWARM missions. This study presents a detailed picture of the low‐latitude ionosphere response over the Brazilian sector during a minor storm. Our results showed that the minor CIR/HSS‐driven storm caused a positive ionospheric storm of over ∼20 TECU in magnitude. For the first time, periodic post‐sunset irregularities and Equatorial Plasma Bubbles, equatorial plasma bubbles, were analyzed using GOLD FUV OI 135.6 nm emission, Total Electron Content (TEC) maps, Rate of TEC index, ROTI, and TEC gradients. Fluctuations in the interplanetary magnetic field Bz and changes in the thermospheric column density ratio (∑O/N2) are discussed as the main sources of ionospheric changes during the storm. This paper highlights the importance of monitoring and understanding the impact of Sun‐Earth interactions and provides insight into the behavior of the low‐latitude ionosphere during minor geomagnetic storms.","PeriodicalId":22181,"journal":{"name":"Space Weather","volume":"23 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83232013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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