A. Schillings, L. Palin, Gemma E. Bower, H. Opgenoorth, S. Milan, K. Kauristie, L. Juusola, G. Reeves, M. Henderson, L. Paxton, M. Lester, M. Hamrin, M. van de Kamp
During the long main phase of the St Patrick's Day storm on Mar 17, 2015, we found three separate enhancements of the westward electrojet. These enhancements are observed in the ionospheric equivalent currents computed using geomagnetic data over Fennoscandia. Using data from the IMAGE magnetometer network, we identified localised field-aligned current (FAC) systems superimposed on the pre-existing ionospheric current system. We suggest that these localised current systems are wedgelets and that they can potentially contribute to a larger-scale structure of a substorm current wedge (SCW). Each wedgelet is associated with a negative BX spike. Each spike is recorded at a higher latitude than the former one and all three are very localised over Fennoscandia. The first spike occurred at 17:34 UT and observed at Lycksele, Rørvik and Nurmijärvi, the second spike was recorded at 17:41 UT and located at Lycksele and Rørvik, whereas the last spike occurred at 17:47 UT and was observed at Kevo and Abisko. Simultaneous optical auroral data and electron injections at the geosynchronous orbit indicate that one or more substorms took place in the polar ionosphere at the time of the wedgelets. This study demonstrates the occurrence of small and short-lived structures such as wedgelets at different locations over a short time scale, 15 min in this case.
{"title":"Signatures of wedgelets over Fennoscandia during the St Patrick's Day Storm 2015","authors":"A. Schillings, L. Palin, Gemma E. Bower, H. Opgenoorth, S. Milan, K. Kauristie, L. Juusola, G. Reeves, M. Henderson, L. Paxton, M. Lester, M. Hamrin, M. van de Kamp","doi":"10.1051/swsc/2023018","DOIUrl":"https://doi.org/10.1051/swsc/2023018","url":null,"abstract":"During the long main phase of the St Patrick's Day storm on Mar 17, 2015, we found three separate enhancements of the westward electrojet. These enhancements are observed in the ionospheric equivalent currents computed using geomagnetic data over Fennoscandia. Using data from the IMAGE magnetometer network, we identified localised field-aligned current (FAC) systems superimposed on the pre-existing ionospheric current system. We suggest that these localised current systems are wedgelets and that they can potentially contribute to a larger-scale structure of a substorm current wedge (SCW). Each wedgelet is associated with a negative BX spike. Each spike is recorded at a higher latitude than the former one and all three are very localised over Fennoscandia. The first spike occurred at 17:34 UT and observed at Lycksele, Rørvik and Nurmijärvi, the second spike was recorded at 17:41 UT and located at Lycksele and Rørvik, whereas the last spike occurred at 17:47 UT and was observed at Kevo and Abisko. Simultaneous optical auroral data and electron injections at the geosynchronous orbit indicate that one or more substorms took place in the polar ionosphere at the time of the wedgelets. This study demonstrates the occurrence of small and short-lived structures such as wedgelets at different locations over a short time scale, 15 min in this case.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47030634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
S. Musset, K. Klein, N. Fuller, G. Khreich, Antonin Wargnier
The most energetic particles accelerated in solar eruptive events are protons and nuclei with energies that may reach a few tens of GeV. They can be detected on the Earth through the secondaries they produce when interacting with the atmosphere. Solar energetic particle events where this happens are called Ground-Level Enhancements (GLEs). Their study is relevant on the one hand because the high particle energies pose particularly strong challenges to the understanding of the acceleration processes. On the other hand, the secondary particles constitute a source of radiation in the atmosphere that may temporarily exceed the permanent dose rate from galactic cosmic rays. This makes the monitoring of radiation doses received by aircrew from GLEs one issue of space weather services for civil aviation. This study addresses the time profiles of GLEs, in the search of commonalities that can be used to constrain models of acceleration and propagation and to forecast the evolution of an ongoing event. We investigate historical GLEs (1971-2012) with the worldwide network of neutron monitors, comparing the rise and the decay as observed by the neutron monitor with the strongest response. The sample comprises 23 events. We evaluate statistical correlations between rise time and decay time inferred from fits to the time profiles, and compute a normalised median GLE time profile. An empirical correlation reported in earlier work between the observed rise times and decay times of the neutron monitor count rate profiles is confirmed. We find indications of a statistical relationship between the rise times and the parent eruptive activity. We discuss ideas on the mechanisms behind the correlation of rise and decay times and on its usefulness for space weather services.
{"title":"The time profile of relativistic solar particle events as observed by neutron monitors","authors":"S. Musset, K. Klein, N. Fuller, G. Khreich, Antonin Wargnier","doi":"10.1051/swsc/2023016","DOIUrl":"https://doi.org/10.1051/swsc/2023016","url":null,"abstract":"The most energetic particles accelerated in solar eruptive events are protons and nuclei with energies that may reach a few tens of GeV. They can be detected on the Earth through the secondaries they produce when interacting with the atmosphere. Solar energetic particle events where this happens are called Ground-Level Enhancements (GLEs). Their study is relevant on the one hand because the high particle energies pose particularly strong challenges to the understanding of the acceleration processes. On the other hand, the secondary particles constitute a source of radiation in the atmosphere that may temporarily exceed the permanent dose rate from galactic cosmic rays. This makes the monitoring of radiation doses received by aircrew from GLEs one issue of space weather services for civil aviation. This study addresses the time profiles of GLEs, in the search of commonalities that can be used to constrain models of acceleration and propagation and to forecast the evolution of an ongoing event. We investigate historical GLEs (1971-2012) with the worldwide network of neutron monitors, comparing the rise and the decay as observed by the neutron monitor with the strongest response. The sample comprises 23 events. We evaluate statistical correlations between rise time and decay time inferred from fits to the time profiles, and compute a normalised median GLE time profile. An empirical correlation reported in earlier work between the observed rise times and decay times of the neutron monitor count rate profiles is confirmed. We find indications of a statistical relationship between the rise times and the parent eruptive activity. We discuss ideas on the mechanisms behind the correlation of rise and decay times and on its usefulness for space weather services.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48192303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
André Ricardo Fazanaro Martinon, S. Stephany, Eurico Rodrigues de Paula
Ionospheric scintillation disturbs radio frequency signals affecting GNSS-based navigation, especially in Brazil, due to the large magnetic declination. The generation of real-time scintillation maps is an important way to provide scintillation monitoring. This work considers amplitude scintillation, given by the S4 index. Some existing and some proposed approaches for generating these maps are presented and tested, being each one a combination of an interpolation method with some existing and/or proposed sets of pre-processing options. These approaches are named after the related interpolation method as GRIDDATA, Inverse Distance Weighting, Radial Basis Functions and Gaussian Process Regression. The making of scintillation maps requires the interpolation of Ionospheric Pierce Point (IPP) samples, given by the S4 values for each IPP of each satellite-station link considering the set of GNSS stations of the given area and time interval. Some intervals of time that presented strong scintillation over Brazil were selected and the corresponding sets of IPP samples were used to obtain sequences of maps using all possible combinations of interpolation and pre-processing options. Furthermore, a fifth, more recent, approach was also included in the comparison. The quality of the resulting maps was assessed, concluding that the Gaussian Process Regression approach, with a specific set of pre-processing options, allows to generate the most accurate scintillation maps. The proposed map generation approach is part of a broader proposal being implemented to provide real-time scintillation maps covering the Brazilian territory.
{"title":"A new approach for the generation of real-time GNSS low-latitude ionospheric scintillation maps","authors":"André Ricardo Fazanaro Martinon, S. Stephany, Eurico Rodrigues de Paula","doi":"10.1051/swsc/2023015","DOIUrl":"https://doi.org/10.1051/swsc/2023015","url":null,"abstract":"Ionospheric scintillation disturbs radio frequency signals affecting GNSS-based navigation, especially in Brazil, due to the large magnetic declination. The generation of real-time scintillation maps is an important way to provide scintillation monitoring. This work considers amplitude scintillation, given by the S4 index. Some existing and some proposed approaches for generating these maps are presented and tested, being each one a combination of an interpolation method with some existing and/or proposed sets of pre-processing options. These approaches are named after the related interpolation method as GRIDDATA, Inverse Distance Weighting, Radial Basis Functions and Gaussian Process Regression. The making of scintillation maps requires the interpolation of Ionospheric Pierce Point (IPP) samples, given by the S4 values for each IPP of each satellite-station link considering the set of GNSS stations of the given area and time interval. Some intervals of time that presented strong scintillation over Brazil were selected and the corresponding sets of IPP samples were used to obtain sequences of maps using all possible combinations of interpolation and pre-processing options. Furthermore, a fifth, more recent, approach was also included in the comparison. The quality of the resulting maps was assessed, concluding that the Gaussian Process Regression approach, with a specific set of pre-processing options, allows to generate the most accurate scintillation maps. The proposed map generation approach is part of a broader proposal being implemented to provide real-time scintillation maps covering the Brazilian territory.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44704277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
C. Siemes, C. Borries, S. Bruinsma, I. Fernández-Gómez, N. Hładczuk, J. van den Ijssel, Timothy Kodikara, K. Vielberg, P. Visser
We present new neutral mass density and crosswind observations for the CHAMP, GRACE, and GRACE-FO missions, filling the last gaps in our database of accelerometer-derived thermosphere observations. For consistency, we processed the data over the entire lifetime of these missions, noting that the results for GRACE in 2011-2017 and GRACE-FO are entirely new. All accelerometer data are newly calibrated. We modeled the temperature-induced bias variations for the GRACE accelerometer data to counter the detrimental effects of the accelerometer thermal control deactivation in April 2011. Further, we developed a new radiation pressure model, which uses ray tracing to account for shadowing and multiple reflections and calculates the satellite's thermal emissions based on the illumination history. The advances in calibration and radiation pressure modeling are essential when the radiation pressure acceleration is significant compared to the aerodynamic one above 450 km altitude during low solar activity, where the GRACE and GRACE-FO satellites spent a considerable fraction of their mission lifetime. The mean of the new density observations changes only marginally, but their standard deviation shows a substantial reduction compared to thermosphere models, up to 15% for GRACE in 2009. The mean and standard deviation of the new GRACE-FO density observations are in good agreement with the GRACE observations. The GRACE and CHAMP crosswind observations agree well with the physics-based TIE-GCM winds, particularly the polar wind patterns. The mean observed crosswind is a few tens of m/s larger than the model one, which we attribute primarily to the crosswind errors being positive by the definition of the retrieval algorithm. The correlation between observed and model crosswind is about 60%, except for GRACE in 2004-2011 when the signal was too small to retrieve crosswinds reliably.
{"title":"New Thermosphere Neutral Mass Density and Crosswind Datasets from CHAMP, GRACE, and GRACE-FO","authors":"C. Siemes, C. Borries, S. Bruinsma, I. Fernández-Gómez, N. Hładczuk, J. van den Ijssel, Timothy Kodikara, K. Vielberg, P. Visser","doi":"10.1051/swsc/2023014","DOIUrl":"https://doi.org/10.1051/swsc/2023014","url":null,"abstract":"We present new neutral mass density and crosswind observations for the CHAMP, GRACE, and GRACE-FO missions, filling the last gaps in our database of accelerometer-derived thermosphere observations. For consistency, we processed the data over the entire lifetime of these missions, noting that the results for GRACE in 2011-2017 and GRACE-FO are entirely new. All accelerometer data are newly calibrated. We modeled the temperature-induced bias variations for the GRACE accelerometer data to counter the detrimental effects of the accelerometer thermal control deactivation in April 2011. Further, we developed a new radiation pressure model, which uses ray tracing to account for shadowing and multiple reflections and calculates the satellite's thermal emissions based on the illumination history. The advances in calibration and radiation pressure modeling are essential when the radiation pressure acceleration is significant compared to the aerodynamic one above 450 km altitude during low solar activity, where the GRACE and GRACE-FO satellites spent a considerable fraction of their mission lifetime. The mean of the new density observations changes only marginally, but their standard deviation shows a substantial reduction compared to thermosphere models, up to 15% for GRACE in 2009. The mean and standard deviation of the new GRACE-FO density observations are in good agreement with the GRACE observations. The GRACE and CHAMP crosswind observations agree well with the physics-based TIE-GCM winds, particularly the polar wind patterns. The mean observed crosswind is a few tens of m/s larger than the model one, which we attribute primarily to the crosswind errors being positive by the definition of the retrieval algorithm. The correlation between observed and model crosswind is about 60%, except for GRACE in 2004-2011 when the signal was too small to retrieve crosswinds reliably.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49506544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Jone Øvretvedt Edvartsen, V. Maliniemi, H. Nesse Tyssøy, S. Hatch
We investigate the connection between the interplanetary magnetic field (IMF) B$_text{y}$-component and polar surface pressure, also known as the Mansurov effect. The aim of the investigation is to unravel potential dependencies on specific seasons and/or solar wind sector structures, and it serves as a sequel to Edvartsen et al. (2022). The mechanism for the effect includes the ability of the IMF to modulate the global electric circuit (GEC), which is theorized to impact and modulate cloud generation processes. By usage of daily ERA5 reanalysis data for geopotential height since 1968, we find no significant response confirming the current Mansurov hypothesis. However, we do find statistically significant correlations on decadal timescales in the time period March-May (MAM) in the northern hemisphere, but with an unusual timing. Similar phased anomalies are also found in the southern hemisphere for MAM, but not at a significant level. In an attempt to explain the unusual timing, heliospheric current sheet crossing events, which are highly correlated with the B$_text{y}$-index, are used. These events result in higher statistical significance in the NH for the MAM period, but cannot fully explain the timing of the response. In general, these statistically significant correlations differ from previously reported evidence on the Mansurov effect, and suggest a revision of the Mansurov hypothesis. Our results also highlights a general feature of time-lagged cross correlation with autocorrelated variables, where the correlation value itself is shown to be a fragile indicator of robustness of a signal. For future studies, we suggest that the $p$-values obtained by modern statistical methods are considered, and not the correlation values alone.
{"title":"The Mansurov effect: Seasonal and solar wind sector structure dependence","authors":"Jone Øvretvedt Edvartsen, V. Maliniemi, H. Nesse Tyssøy, S. Hatch","doi":"10.1051/swsc/2023013","DOIUrl":"https://doi.org/10.1051/swsc/2023013","url":null,"abstract":"We investigate the connection between the interplanetary magnetic field (IMF) B$_text{y}$-component and polar surface pressure, also known as the Mansurov effect.\u0000 The aim of the investigation is to unravel potential dependencies on specific seasons and/or solar wind sector structures, and it serves as a sequel to Edvartsen et al. (2022). \u0000 The mechanism for the effect includes the ability of the IMF to modulate the global electric circuit (GEC), which is theorized to impact and modulate cloud generation processes. By usage of daily ERA5 reanalysis data for geopotential height since 1968, we find no significant response confirming the current Mansurov hypothesis. However, we do find statistically significant correlations on decadal timescales in the time period March-May (MAM) in the northern hemisphere, but with an unusual timing. Similar phased anomalies are also found in the southern hemisphere for MAM, but not at a significant level. In an attempt to explain the unusual timing, heliospheric current sheet crossing events, which are highly correlated with the B$_text{y}$-index, are used. These events result in higher statistical significance in the NH for the MAM period, but cannot fully explain the timing of the response. In general, these statistically significant correlations differ from previously reported evidence on the Mansurov effect, and suggest a revision of the Mansurov hypothesis. Our results also highlights a general feature of time-lagged cross correlation with autocorrelated variables, where the correlation value itself is shown to be a fragile indicator of robustness of a signal. For future studies, we suggest that the $p$-values obtained by modern statistical methods are considered, and not the correlation values alone.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44288378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Lisa Marie Buschmann, John William Bonnell, S. Bounds, Lasse Boy Novock Clausen, C. Kletzing, S. Marholm, Wojciech Jacek Miloch, R. Roglans, A. Spicher
The plasma in the cusp ionosphere is subject to particle precipitation, which is important for the development of large scale irregularities in the plasma density. These irregularities can be broken down to smaller scales which have been linked to strong scintillations in the Global Navigation Satellite System (GNSS) signals. We present power spectra for the plasma density irregularities in the cusp ionosphere for regions with and without auroral particle precipitation based on in-situ measurements from the Twin Rockets to Investigate Cusp Electrodynamics-2 (TRICE-2) mission, consisting of two sounding rockets flying simultaneously at different altitudes. The electron density measurements taken from the multi-needle Langmuir probe system (m-NLP) were analyzed for the whole flight duration for both rockets. Due to their high sampling rates, the probes allow for a study of plasma irregularities down to kinetic scales. A steepening of the slope in the power spectra may indicate two regimes, a frequency interval with a shallow slope, where fluid-like processes are dominating, and an interval with a steeper slope which can be addressed with kinetic theory. The steepening occurs at frequencies between 20 and 100 Hz with a median similar to the oxygen gyrofrequency. Additionally, the occurrence of double slopes increases where precipitation starts and throughout the rest of the flight. In addition, strong electron density fluctuations were found in regions poleward of the cusp, thus in regions immediately after precipitation. Furthermore, by investigating the integrated power of the fluctuations within different frequency ranges, we show that at low frequencies (10-100 Hz), the power is pronounced more evenly while the rocket encounters particle precipitation, while at high frequencies (100-1000 Hz) fluctuations essentially coincide with the passing through a flow channel.
{"title":"The role of particle precipitation on plasma structuring at different altitudes by in-situ measurements","authors":"Lisa Marie Buschmann, John William Bonnell, S. Bounds, Lasse Boy Novock Clausen, C. Kletzing, S. Marholm, Wojciech Jacek Miloch, R. Roglans, A. Spicher","doi":"10.1051/swsc/2023012","DOIUrl":"https://doi.org/10.1051/swsc/2023012","url":null,"abstract":"The plasma in the cusp ionosphere is subject to particle precipitation, which is important for the development of large scale irregularities in the plasma density. These irregularities can be broken down to smaller scales which have been linked to strong scintillations in the Global Navigation Satellite System (GNSS) signals. We present power spectra for the plasma density irregularities in the cusp ionosphere for regions with and without auroral particle precipitation based on in-situ measurements from the Twin Rockets to Investigate Cusp Electrodynamics-2 (TRICE-2) mission, consisting of two sounding rockets flying simultaneously at different altitudes. The electron density measurements taken from the multi-needle Langmuir probe system (m-NLP) were analyzed for the whole flight duration for both rockets. Due to their high sampling rates, the probes allow for a study of plasma irregularities down to kinetic scales. \u0000A steepening of the slope in the power spectra may indicate two regimes, a frequency interval with a shallow slope, where fluid-like processes are dominating, and an interval with a steeper slope which can be addressed with kinetic theory. The steepening occurs at frequencies between 20 and 100 Hz with a median similar to the oxygen gyrofrequency. Additionally, the occurrence of double slopes increases where precipitation starts and throughout the rest of the flight. In addition, strong electron density fluctuations were found in regions poleward of the cusp, thus in regions immediately after precipitation.\u0000Furthermore, by investigating the integrated power of the fluctuations within different frequency ranges, we show that at low frequencies (10-100 Hz), the power is pronounced more evenly while the rocket encounters particle precipitation, while at high frequencies (100-1000 Hz) fluctuations essentially coincide with the passing through a flow channel.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44536414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Co-rotating Interaction Regions (CIRs) are complex structures in the Heliosphere that arise from the interaction of fast and slow solar wind streams. The interface between fast and slow solar wind is called the stream interface, which often has considerable north-south tilt. We apply a sliding window correlation method on multi-spacecraft data in order to obtain the time delay between the spacecraft. Using these time delays and in-situ solar wind velocity measurements, we can shift the positions of two spacecraft, and, together with the position of the reference spacecraft, we can reconstruct the spatial orientation of the stream interface. We examined four CIRs from two different solar sources at the beginning of 2007 using ACE, WIND and STEREO-A spacecraft data. The gradually increasing distance between STEREO-A and the other spacecraft provide an opportunity to determine the effects of spacecraft separation on the quality of the results. In three out of the four events, the determined planes generally follow the Parker spiral in the ecliptic, their off-ecliptic tilt is determined by the position of the source of the high-speed stream. For the fourth event, STEREO-A was probably too far away for this method to be successfully applicable.
{"title":"Orientation of the stream interface in CIRs","authors":"Gergely Koban, A. Opitz, N. Biro, Z. Németh","doi":"10.1051/swsc/2023011","DOIUrl":"https://doi.org/10.1051/swsc/2023011","url":null,"abstract":"Co-rotating Interaction Regions (CIRs) are complex structures in the Heliosphere that arise from the interaction of fast and slow solar wind streams. The interface between fast and slow solar wind is called the stream interface, which often has considerable north-south tilt. We apply a sliding window correlation method on multi-spacecraft data in order to obtain the time delay between the spacecraft. Using these time delays and in-situ solar wind velocity measurements, we can shift the positions of two spacecraft, and, together with the position of the reference spacecraft, we can reconstruct the spatial orientation of the stream interface. We examined four CIRs from two different solar sources at the beginning of 2007 using ACE, WIND and STEREO-A spacecraft data. The gradually increasing distance between STEREO-A and the other spacecraft provide an opportunity to determine the effects of spacecraft separation on the quality of the results. In three out of the four events, the determined planes generally follow the Parker spiral in the ecliptic, their off-ecliptic tilt is determined by the position of the source of the high-speed stream. For the fourth event, STEREO-A was probably too far away for this method to be successfully applicable.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45472355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Isaac Wright, Ishita Solanki, Anupa Desai, Josemaria Gomez Socola, F. Rodrigues
Distributed arrays of ground-based instruments can help advance observations and improve understanding of space weather. The implementation of an array of sensors can be constrained, however, by the high cost of commercial instruments and the availability of internet and power. Additionally, distributed observations require sensors that can be easily deployed and maintained. As part of an effort to expand the breath of skills of physics students while increasing literacy about space weather, a team of undergraduates was formed and tasked with designing, building, and testing an autonomous platform for ionospheric observations using ScintPi 3.0. ScintPi 3.0 is a low-cost ionospheric scintillation and total electron content (TEC) monitor. The design led to a platform that employs cellular-based internet connectivity as well as solar and battery power. A fully functional prototype was built and deployed near Dallas, USA (32.9oN, 96.4oW). Results show that the platform can run for 232 hours using battery only or indefinitely when connected to the selected solar photovoltaic panel. For system monitoring, LTE functionality enables near real-time updates of the systems’ health and remote shell access. Examples of observations made by the prototype are presented, including the detection of ionospheric effects caused by a space weather event. Additionally, the potential of the system for research, education, and citizen science initiatives are discussed.
{"title":"Student-led design, development and tests of an autonomous, low-cost platform for distributed space weather observations","authors":"Isaac Wright, Ishita Solanki, Anupa Desai, Josemaria Gomez Socola, F. Rodrigues","doi":"10.1051/swsc/2023010","DOIUrl":"https://doi.org/10.1051/swsc/2023010","url":null,"abstract":"Distributed arrays of ground-based instruments can help advance observations and improve understanding of space weather. The implementation of an array of sensors can be constrained, however, by the high cost of commercial instruments and the availability of internet and power. Additionally, distributed observations require sensors that can be easily deployed and maintained. As part of an effort to expand the breath of skills of physics students while increasing literacy about space weather, a team of undergraduates was formed and tasked with designing, building, and testing an autonomous platform for ionospheric observations using ScintPi 3.0. ScintPi 3.0 is a low-cost ionospheric scintillation and total electron content (TEC) monitor. The design led to a platform that employs cellular-based internet connectivity as well as solar and battery power. A fully functional prototype was built and deployed near Dallas, USA (32.9oN, 96.4oW). Results show that the platform can run for 232 hours using battery only or indefinitely when connected to the selected solar photovoltaic panel. For system monitoring, LTE functionality enables near real-time updates of the systems’ health and remote shell access. Examples of observations made by the prototype are presented, including the detection of ionospheric effects caused by a space weather event. Additionally, the potential of the system for research, education, and citizen science initiatives are discussed.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49530957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Context: The main challenge in atmospheric ionisation modelling is that sparse measurements are used to derive a global precipitation pattern. Typically this requires intense interpolation or scaling of long-term average maps. In some regions however, the particle flux might be similar and a combination of these regions would not limit the results even though it would dramatically improve the spatial and temporal data coverage. Aims: The intention of this paper is to statistically analyse the particle flux distribution close to the geomagnetic poles labelled as Polar Particle Flux Distribution (PPFD) and identify similar distributions in neighbouring bins. Those bins are grouped together and the size of the PPFD-area is estimated. The benefit is that single measurements within the PPFD-area should be able to represent the particle flux for the whole area at a given time. Methods: We use spatially binned energetic particle flux distributions measured by POES and Metop spacecraft during 2001--2018 to identify a Kp-dependent area with a similar flux distribution as the one found close to the geomagnetic poles (|magn. lat|>86°). First, the particle flux is mapped on a magnetic local time (MLT) vs. magnetic latitude grid. In a second step the gridded data is split up according to Kp-levels (forming the final bins). Third, the particle flux in every bin has been recalculated in order to replace zero-count rates by rates based on longer measurement periods which results in more realistic low flux end of the particle distribution. Then the binned flux distributions are compared to the PPFD. A "$Delta$-test" indicates the similarity. A threshold for the $Delta$-test is defined using the standard deviation of $Delta$-test values inside the (|magn. lat|>86°) area. Bins that meet the threshold are attributed as PPFD-area. Results: Polar Particle Flux Distributions and the corresponding PPFD-areas have been determined for all investigated particle channels, covering an energy range of 154~eV--300~keV for electrons and 154~eV--2.5~MeV for protons. Concerning low energy channels a gradual flux increase with rising Kp has been identified. High energy channels show a combination of background population and solar particle event (SPE) population that adds up with increasing Kp. The size of the PPFD-area depends on particle species, energy and geomagnetic disturbance, as well as MLT. The main findings are: a)~There are small but characteristic hemispheric differences. b)~Only above a certain energy threshold the PPFD-areas increase with particle energy. c)~A clear enlargement with rising Kp is identified - with exceptions for very low Kp. d)~The centre of the PPFD-area is shifted towards midnight and moves with Kp. Asymmetries of the boundaries could be explained by auroral intensity. e)~For low energy particles the main restriction of the PPFD-area seems to be the auroral precipitation.
{"title":"Polar particle flux distribution and its spatial extent","authors":"O. Yakovchuk, Jan Maik Wissing","doi":"10.1051/swsc/2023009","DOIUrl":"https://doi.org/10.1051/swsc/2023009","url":null,"abstract":"Context: The main challenge in atmospheric ionisation modelling is that sparse measurements are used to derive a global precipitation pattern. Typically this requires intense interpolation or scaling of long-term average maps.\u0000In some regions however, the particle flux might be similar and a combination of these regions would not limit the results even though it would dramatically improve the spatial and temporal data coverage.\u0000Aims: The intention of this paper is to statistically analyse the particle flux distribution close to the geomagnetic poles labelled as Polar Particle Flux Distribution (PPFD) and identify similar distributions in neighbouring bins. Those bins are grouped together and the size of the PPFD-area is estimated. The benefit is that single measurements within the PPFD-area should be able to represent the particle flux for the whole area at a given time.\u0000Methods: We use spatially binned energetic particle flux distributions measured by POES and Metop spacecraft during 2001--2018 to identify a Kp-dependent area with a similar flux distribution as the one found close to the geomagnetic poles (|magn. lat|>86°).\u0000First, the particle flux is mapped on a magnetic local time (MLT) vs. magnetic latitude grid.\u0000In a second step the gridded data is split up according to Kp-levels (forming the final bins).\u0000Third, the particle flux in every bin has been recalculated in order to replace zero-count rates by rates based on longer measurement periods which results in more realistic low flux end of the particle distribution.\u0000Then the binned flux distributions are compared to the PPFD. A \"$Delta$-test\" indicates the similarity. A threshold for the $Delta$-test is defined using the standard deviation of $Delta$-test values inside the (|magn. lat|>86°) area. Bins that meet the threshold are attributed as PPFD-area.\u0000Results:\u0000Polar Particle Flux Distributions and the corresponding PPFD-areas have been determined for all investigated particle channels, covering an energy range of 154~eV--300~keV for electrons and 154~eV--2.5~MeV for protons.\u0000Concerning low energy channels a gradual flux increase with rising Kp has been identified. High energy channels show a combination of background population and solar particle event (SPE) population that adds up with increasing Kp.\u0000The size of the PPFD-area depends on particle species, energy and geomagnetic disturbance, as well as MLT. The main findings are:\u0000a)~There are small but characteristic hemispheric differences.\u0000b)~Only above a certain energy threshold the PPFD-areas increase with particle energy.\u0000c)~A clear enlargement with rising Kp is identified - with exceptions for very low Kp.\u0000d)~The centre of the PPFD-area is shifted towards midnight and moves with Kp. Asymmetries of the boundaries could be explained by auroral intensity. e)~For low energy particles the main restriction of the PPFD-area seems to be the auroral precipitation.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47335806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
V. Réville, N. Poirier, A. Kouloumvakos, A. Rouillard, R. Pinto, N. Fargette, M. Indurain, Raphael Fournon, Théo James, Raphaël Pobeda, Cyril Scoul
We present a new 3D MHD heliospheric model for space-weather forecasting driven by boundary conditions defined from white-light observations of the solar corona. The model is based on the MHD code PLUTO, constrained by an empirical derivation of the solar wind background properties at 0.1au. This empirical method uses white-light observations to estimate the position of the heliospheric current sheet. The boundary conditions necessary to run Heliocast are then defined from pre-defined relations between the necessary MHD properties (speed, density and temperature) and the distance to the current sheet. We assess the accuracy of the model over six Carrington rotations during the first semester of 2018. Using point-by-point metrics and event based analysis, we evaluate the performances of our model varying the angular width of the slow solar wind layer surrounding the heliospheric current sheet. We also compare our empirical technique with two well tested models of the corona: Multi-VP and WindPredict-AW. We find that our method is well suited to reproduce high speed streams, and does --for well chosen parameters-- better than full MHD models. The model shows, nonetheless, limitations that could worsen for rising and maximum solar activity.
{"title":"HelioCast: heliospheric forecasting based on white-light observations of the solar corona. I. Solar minimum conditions","authors":"V. Réville, N. Poirier, A. Kouloumvakos, A. Rouillard, R. Pinto, N. Fargette, M. Indurain, Raphael Fournon, Théo James, Raphaël Pobeda, Cyril Scoul","doi":"10.1051/swsc/2023008","DOIUrl":"https://doi.org/10.1051/swsc/2023008","url":null,"abstract":"We present a new 3D MHD heliospheric model for space-weather forecasting driven by boundary conditions defined from white-light observations of the solar corona. The model is based on the MHD code PLUTO, constrained by an empirical derivation of the solar wind background properties at 0.1au. This empirical method uses white-light observations to estimate the position of the heliospheric current sheet. The boundary conditions necessary to run Heliocast are then defined from pre-defined relations between the necessary MHD properties (speed, density and temperature) and the distance to the current sheet. We assess the accuracy of the model over six Carrington rotations during the first semester of 2018. Using point-by-point metrics and event based analysis, we evaluate the performances of our model varying the angular width of the slow solar wind layer surrounding the heliospheric current sheet. We also compare our empirical technique with two well tested models of the corona: Multi-VP and WindPredict-AW. We find that our method is well suited to reproduce high speed streams, and does --for well chosen parameters-- better than full MHD models. The model shows, nonetheless, limitations that could worsen for rising and maximum solar activity.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43521939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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