R. Kieokaew, Rui Pinto, Evangelia Samara, C. Tao, M. Indurain, Benoit Lavraud, Antoine Brunet, V. Génot, Alexis Rouillard, Nicolas André, Sébastien Bourdarie, Christos Katsavrias, Fabien Darrouzet, Benjamin Grison, Ioannis Daglis
Developing an automated pipeline for solar-wind condition prediction upstream of Earth is an important step for transitioning from space weather research to operation. We develop a prototype pipeline called “Helio1D” to model ambient solar wind conditions comprising temporal profiles of wind speed, density, temperature and tangential magnetic field at L1 up to 4 days in advance. The prototype pipeline connects MULTI-VP coronal model that provides daily predictions of the solar wind at 0.14 AU and a 1D magnetohydrodynamics (MHD) model that propagates the solar wind to 1 AU. As a part of development towards a better performing operational pipeline in the future, our present work focuses on the proof-of-concept, initial implementation, and validation of Helio1D. Here, we first benchmark Helio1D using the synoptic magnetograms provided by Wilcox Space Observatory as inputs to the coronal part of MULTI-VP for the intervals in 2004 -- 2013 and 2017 -- 2018. Using the classic point-to-point metrics, it is found that Helio1D underperforms the 27-day recurrence model for all time intervals, while outperforms the 4-day persistence model in the late declining phase of the solar cycle. As a complementary analysis, we evaluate the time and magnitude differences between Helio1D and the observations by exploiting the Fast Dynamic Time Warping technique, which allows us to discuss Helio1D caveats and address calibration to improve the Helio1D performance. Furthermore, we model several solar wind conditions in parallel, for a total of 21 profiles corresponding to various virtual targets to provide uncertainties. Although our prototype pipeline shows less satisfactory results compared to existing works, it is fully automated and computationally fast, both of which are desirable qualities for operational forecasting. Our strategies for future improvements towards a better performing pipeline are addressed.
为地球上游的太阳风状况预测开发一个自动管道，是从空间气象研究过渡到运行的重要一步。我们开发了一个名为 "Helio1D "的原型管道，用于模拟环境太阳风状况，包括 L1 的风速、密度、温度和切向磁场的时间剖面，可提前 4 天进行模拟。原型管道将提供 0.14 AU 太阳风每日预测的 MULTI-VP 日冕模型和将太阳风传播到 1 AU 的一维磁流体动力学（MHD）模型连接起来。作为未来开发性能更好的运行管道的一部分，我们目前的工作重点是Helio1D的概念验证、初步实施和验证。在此，我们首先使用威尔科克斯空间天文台提供的同步磁图作为MULTI-VP日冕部分的输入，对2004-2013年和2017-2018年期间的Helio1D进行基准测试。使用经典的点对点指标，我们发现Helio1D在所有时间间隔内的表现都不如27天重现模型，而在太阳周期晚期的下降阶段则优于4天持续模型。作为补充分析，我们利用快速动态时间扭曲技术评估了Helio1D与观测数据之间的时间和幅度差异，从而讨论了Helio1D的注意事项，并解决了校准问题，以提高Helio1D的性能。此外，我们还并行模拟了几种太阳风条件，总共 21 个剖面与各种虚拟目标相对应，以提供不确定性。虽然我们的原型管道显示出的结果不如现有工作那么令人满意，但它是完全自动化的，计算速度也很快，这两点都是业务预报所需要的。我们还讨论了未来的改进策略，以实现性能更佳的管道。
{"title":"Helio1D modeling of temporal variation of solar wind: interfacing between Multi-VP and 1D MHD for future operational forecasting at L1","authors":"R. Kieokaew, Rui Pinto, Evangelia Samara, C. Tao, M. Indurain, Benoit Lavraud, Antoine Brunet, V. Génot, Alexis Rouillard, Nicolas André, Sébastien Bourdarie, Christos Katsavrias, Fabien Darrouzet, Benjamin Grison, Ioannis Daglis","doi":"10.1051/swsc/2024018","DOIUrl":"https://doi.org/10.1051/swsc/2024018","url":null,"abstract":"Developing an automated pipeline for solar-wind condition prediction upstream of Earth is an important step for transitioning from space weather research to operation. We develop a prototype pipeline called “Helio1D” to model ambient solar wind conditions comprising temporal profiles of wind speed, density, temperature and tangential magnetic field at L1 up to 4 days in advance. The prototype pipeline connects MULTI-VP coronal model that provides daily predictions of the solar wind at 0.14 AU and a 1D magnetohydrodynamics (MHD) model that propagates the solar wind to 1 AU. As a part of development towards a better performing operational pipeline in the future, our present work focuses on the proof-of-concept, initial implementation, and validation of Helio1D. Here, we first benchmark Helio1D using the synoptic magnetograms provided by Wilcox Space Observatory as inputs to the coronal part of MULTI-VP for the intervals in 2004 -- 2013 and 2017 -- 2018. Using the classic point-to-point metrics, it is found that Helio1D underperforms the 27-day recurrence model for all time intervals, while outperforms the 4-day persistence model in the late declining phase of the solar cycle. As a complementary analysis, we evaluate the time and magnitude differences between Helio1D and the observations by exploiting the Fast Dynamic Time Warping technique, which allows us to discuss Helio1D caveats and address calibration to improve the Helio1D performance. Furthermore, we model several solar wind conditions in parallel, for a total of 21 profiles corresponding to various virtual targets to provide uncertainties. Although our prototype pipeline shows less satisfactory results compared to existing works, it is fully automated and computationally fast, both of which are desirable qualities for operational forecasting. Our strategies for future improvements towards a better performing pipeline are addressed.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141107862","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}
Jeffrey J. Love, E. Joshua Rigler, Hisashi Hayakawa, K. Mursula
A study is made of the intensity of the Carrington magnetic storm of September 1859 as inferred from visual measurements of horizontal-component geomagnetic disturbance made at the Colaba observatory in India. Using data from modern observatories, a lognormal statistical model of storm intensity is developed, to characterize the maximum-negative value of the storm-time disturbance index (maximum $-Dst$) versus geomagnetic disturbance recorded at low-latitude observatories during magnetic storms. With this model and a recently published presentation of the Colaba data, the most likely maximum $-Dst$ of the Carrington storm and its credibility interval are estimated. A related model is used to examine individual Colaba disturbance values reported for the Carrington storm. Results indicate that only about one in a million storms with maximum $-Dst$ like the Carrington storm would result in local disturbance greater than that reported from Colaba. This indicates that either the Colaba data were affected by magnetospheric-ionospheric current systems in addition to the ring current, or there might be something wrong with the Colaba data. If the most extreme Colaba disturbance value is included in the analysis, then, of all hypothetical storms generating the hourly average disturbance recorded at Colaba during the Carrington storm, the median maximum $-Dst = 964$~nT, with a 68% credibility interval of $[855,1087]$~nT. If the most extreme Colaba disturbance value is excluded from the analysis, then the median maximum $-Dst = 866$~nT, with a 68% credibility interval of $[768, 977]$~nT. The widths of these intervals indicate that estimates of the occurrence frequency of Carrington-class storms are very uncertain, as are related estimates of risk for modern technological systems.
{"title":"On the Uncertain Intensity Estimate of the 1859 Carrington Storm","authors":"Jeffrey J. Love, E. Joshua Rigler, Hisashi Hayakawa, K. Mursula","doi":"10.1051/swsc/2024015","DOIUrl":"https://doi.org/10.1051/swsc/2024015","url":null,"abstract":"A study is made of the intensity of the Carrington magnetic storm of September 1859 as inferred from visual measurements of horizontal-component geomagnetic disturbance made at the Colaba observatory in India. Using data from modern observatories, a lognormal statistical model of storm intensity is developed, to characterize the maximum-negative value of the storm-time disturbance index (maximum $-Dst$) versus geomagnetic disturbance recorded at low-latitude observatories during magnetic storms. With this model and a recently published presentation of the Colaba data, the most likely maximum $-Dst$ of the Carrington storm and its credibility interval are estimated. A related model is used to examine individual Colaba disturbance values reported for the Carrington storm. Results indicate that only about one in a million storms with maximum $-Dst$ like the Carrington storm would result in local disturbance greater than that reported from Colaba. This indicates that either the Colaba data were affected by magnetospheric-ionospheric current systems in addition to the ring current, or there might be something wrong with the Colaba data. If the most extreme Colaba disturbance value is included in the analysis, then, of all hypothetical storms generating the hourly average disturbance recorded at Colaba during the Carrington storm, the median maximum $-Dst = 964$~nT, with a 68% credibility interval of $[855,1087]$~nT. If the most extreme Colaba disturbance value is excluded from the analysis, then the median maximum $-Dst = 866$~nT, with a 68% credibility interval of $[768, 977]$~nT. The widths of these intervals indicate that estimates of the occurrence frequency of Carrington-class storms are very uncertain, as are related estimates of risk for modern technological systems.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141124779","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}
To understand the similarities and differences between the duskside mesoscale quasistatic field-aligned currents (FACs) and the dawnside mesoscale FACs, we examined the magnetic field data obtained through the constellation measurements of Swarm satellites for a four-year period. The automatic event identification method developed in the previous study (Yokoyama et al., 2021) identified events of quasistatic mesoscale FACs, which are embedded in the diminished dawnside and duskside Region 1/2 current systems, in 774 passes out of 4001 passes on the dawnside, and 443 out of 3755 passes on the duskside, respectively. The dawnside and duskside mesoscale FACs have similar occurrence tendencies such that both have a relatively high occurrence ratio for positive IMF BZ, occur regardless of sunlight conditions, and have the current density increasing with the solar wind proton density. On the other hand, one notable difference was found; the occurrence ratio of the dawnside mesoscale FACs is approximately 1.7 times higher than that of the duskside mesoscale FACs. This difference is discussed in terms of the dawn-dusk asymmetry of the occurrence of Kelvin Helmholtz instabilities on the magnetopause.
为了了解黄昏中尺度准静态场对准电流（FACs）与黎明中尺度 FACs 的异同，我们研究了通过 Swarm 卫星星座测量获得的为期四年的磁场数据。先前研究（Yokoyama 等人，2021 年）中开发的事件自动识别方法分别在黎明侧 4001 次中的 774 次和黄昏侧 3755 次中的 443 次中识别出了准静态中尺度 FAC 事件，这些事件蕴含在减弱的黎明侧和黄昏侧区域 1/2 电流系统中。黎明侧和黄昏侧中尺度FAC具有相似的发生趋势，例如两者在正IMF BZ的发生率都相对较高，发生与日照条件无关，并且电流密度随太阳风质子密度的增加而增加。另一方面，我们也发现了一个明显的差异：黎明中尺度 FAC 的出现比约为黄昏中尺度 FAC 的 1.7 倍。我们将从磁极面开尔文亥姆霍兹不稳定性发生的黎明-黄昏不对称角度来讨论这一差异。
{"title":"The Nature of the mesoscale field-aligned currents in the auroral oval for positive IMF BZ: More frequent occurrence in the dawnside sector than in the duskside sector","authors":"Yoshihiro Yokoyama, Satoshi Taguchi","doi":"10.1051/swsc/2024013","DOIUrl":"https://doi.org/10.1051/swsc/2024013","url":null,"abstract":"To understand the similarities and differences between the duskside mesoscale quasistatic field-aligned currents (FACs) and the dawnside mesoscale FACs, we examined the magnetic field data obtained through the constellation measurements of Swarm satellites for a four-year period. The automatic event identification method developed in the previous study (Yokoyama et al., 2021) identified events of quasistatic mesoscale FACs, which are embedded in the diminished dawnside and duskside Region 1/2 current systems, in 774 passes out of 4001 passes on the dawnside, and 443 out of 3755 passes on the duskside, respectively. The dawnside and duskside mesoscale FACs have similar occurrence tendencies such that both have a relatively high occurrence ratio for positive IMF BZ, occur regardless of sunlight conditions, and have the current density increasing with the solar wind proton density. On the other hand, one notable difference was found; the occurrence ratio of the dawnside mesoscale FACs is approximately 1.7 times higher than that of the duskside mesoscale FACs. This difference is discussed in terms of the dawn-dusk asymmetry of the occurrence of Kelvin Helmholtz instabilities on the magnetopause.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140678083","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}
A. Timár, Andrea Opitz, Zoltan Nemeth, Zsofia Bebesi, N. Biro, Gábor Facskó, G. Koban, Á. Madár
Solar wind parameters at different locations in the inner heliosphere can be estimated using various solar wind extrapolation methods. The simple ballistic method extrapolates solar wind parameters from the point of measurement to a chosen heliospheric position by assuming that major solar wind structures are persistent and arrive relatively unaltered to the target position. The method considers the rotation period of the Sun while assuming a constant solar wind speed during radial propagation. We improve the simple ballistic model by considering the interaction between the slow and the fast solar wind with a pressure-correction during the propagation. Instead of extrapolating from the position of a single spacecraft, we apply this pressure-corrected ballistic method to 2D speed maps of the solar source surface available from solar coronal models to determine the solar wind speed in the inner heliosphere in 3D, between latitudes of ±50°. We also take into account the effects of the solar differential rotation in our model. Our method is simple, fast and it can be applied to different source surface datasets. The results of our model are validated with in situ data from the ACE spacecraft. We find that the pressure-corrected ballistic method can give accurate predictions of the solar wind in 3D.
{"title":"3D pressure-corrected ballistic extrapolation of solar wind speed in the inner heliosphere","authors":"A. Timár, Andrea Opitz, Zoltan Nemeth, Zsofia Bebesi, N. Biro, Gábor Facskó, G. Koban, Á. Madár","doi":"10.1051/swsc/2024010","DOIUrl":"https://doi.org/10.1051/swsc/2024010","url":null,"abstract":"Solar wind parameters at different locations in the inner heliosphere can be estimated using various solar wind extrapolation methods. The simple ballistic method extrapolates solar wind parameters from the point of measurement to a chosen heliospheric position by assuming that major solar wind structures are persistent and arrive relatively unaltered to the target position. The method considers the rotation period of the Sun while assuming a constant solar wind speed during radial propagation. We improve the simple ballistic model by considering the interaction between the slow and the fast solar wind with a pressure-correction during the propagation. Instead of extrapolating from the position of a single spacecraft, we apply this pressure-corrected ballistic method to 2D speed maps of the solar source surface available from solar coronal models to determine the solar wind speed in the inner heliosphere in 3D, between latitudes of ±50°. We also take into account the effects of the solar differential rotation in our model. Our method is simple, fast and it can be applied to different source surface datasets. The results of our model are validated with in situ data from the ACE spacecraft. We find that the pressure-corrected ballistic method can give accurate predictions of the solar wind in 3D.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140694874","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}
José Juan González, P. Riley, M. Ben-Nun, Prateek Mayank, Bhargav Vaidya
Understanding the large-scale three-dimensional structure of the inner heliosphere, while important in its own right, is crucial for space weather applications, such as forecasting the time of arrival and propagation of coronal mass ejections (CMEs). This study uses sunRunner3D (3D), a 3-D magnetohydrodynamic (MHD) model, to simulate solar wind (SW) streams and generate background states. SR3D employs the boundary conditions generated by CORona-HELiosphere (CORHEL) and the PLUTO code to compute the plasma properties of the SW with the MHD approximation up to 1.1 AU in the inner heliosphere. We demonstrate that SR3D reproduces global features of Corotating Interaction Regions (CIRs) observed by Earth-based spacecraft (OMNI) and the Solar TErrestial RElations Observatory (STEREO)-A for a set of Carrington rotations (CRs) that cover a period that lays in the late declining phase of solar cycle 24. Additionally, we demonstrate that the model solutions are valid in the corotating and inertial frames of references. Moreover, a comparison between SR3D simulations and in-situ measurements shows reasonable agreement with the observations, and our results are comparable to those achieved by Predictive Science Inc.'s Magnetohydrodynamic Algorithm outside a Sphere (MAS) code. We have also undertaken a comparative analysis with the Space Weather Adaptive Simulation Framework for Solar Wind (SWASTi-SW), a PLUTO physics-based model, to evaluate the precision of various initial boundary conditions. Finally, we discuss the disparities in the solutions derived from inertial and rotating frames.
{"title":"Using sunRunner3D to interpret the global structure of the heliosphere from in-situ measurements","authors":"José Juan González, P. Riley, M. Ben-Nun, Prateek Mayank, Bhargav Vaidya","doi":"10.1051/swsc/2024014","DOIUrl":"https://doi.org/10.1051/swsc/2024014","url":null,"abstract":"Understanding the large-scale three-dimensional structure of the inner heliosphere, while important in its own right, is crucial for space weather applications, such as forecasting the time of arrival and propagation of coronal mass ejections (CMEs). This study uses sunRunner3D (3D), a 3-D magnetohydrodynamic (MHD) model, to simulate solar wind (SW) streams and generate background states. SR3D employs the boundary conditions generated by CORona-HELiosphere (CORHEL) and the PLUTO code to compute the plasma properties of the SW with the MHD approximation up to 1.1 AU in the inner heliosphere. We demonstrate that SR3D reproduces global features of Corotating Interaction Regions (CIRs) observed by Earth-based spacecraft (OMNI) and the Solar TErrestial RElations Observatory (STEREO)-A for a set of Carrington rotations (CRs) that cover a period that lays in the late declining phase of solar cycle 24. Additionally, we demonstrate that the model solutions are valid in the corotating and inertial frames of references.\u0000 Moreover, a comparison between SR3D simulations and in-situ measurements shows reasonable agreement with the observations, and our results are comparable to those achieved by Predictive Science Inc.'s Magnetohydrodynamic Algorithm outside a Sphere (MAS) code. We have also undertaken a comparative analysis with the Space Weather Adaptive Simulation Framework for Solar Wind (SWASTi-SW), a PLUTO physics-based model, to evaluate the precision of various initial boundary conditions. Finally, we discuss the disparities in the solutions derived from inertial and rotating frames.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140700088","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}
Lidiya Annie John, S. Nyberg, Laura Vuorinen, Rami Vainio, A. Afanasiev, S. Poedts, N. Wijsen
Solar energetic particles (SEPs) are considered a serious radiation threat to space technologies and humans in space. SEPs are accelerated to high energies by solar explosive phenomena such as solar flares and in particular by shocks driven by coronal mass ejections (CMEs). We aim to better understand the effects of magnetic field gradient-induced adiabatic focusing on the coronal acceleration of SEPs and to test whether free-escape boundaries produce the same effects as focusing. We present results from a one-dimensional oblique shock model with a mean free path similar to Bell's (1978) theory using Monte Carlo simulations. We show that the momentum spectrum at a shock and far upstream will attain a steady state in a model with adiabatic focusing, whereas it does not in a non-focusing model. However, the effects of focusing can be mimicked in a non-focused simulation by introducing a free-escape boundary ahead of the shock close to the position where the particles will escape from the shock by focusing in a focused transport simulation. This provides a promising avenue for constructing computationally efficient codes that can model the particle emission from shocks.
{"title":"Effects of adiabatic focusing and free-escape boundaries in coronal shock acceleration","authors":"Lidiya Annie John, S. Nyberg, Laura Vuorinen, Rami Vainio, A. Afanasiev, S. Poedts, N. Wijsen","doi":"10.1051/swsc/2024012","DOIUrl":"https://doi.org/10.1051/swsc/2024012","url":null,"abstract":"Solar energetic particles (SEPs) are considered a serious radiation threat to space technologies and humans in space. SEPs are accelerated to high energies by solar explosive phenomena such as solar flares and in particular by shocks driven by coronal mass ejections (CMEs). We aim to better understand the effects of magnetic field gradient-induced adiabatic focusing on the coronal acceleration of SEPs and to test whether free-escape boundaries produce the same effects as focusing. We present results from a one-dimensional oblique shock model with a mean free path similar to Bell's (1978) theory using Monte Carlo simulations. We show that the momentum spectrum at a shock and far upstream will attain a steady state in a model with adiabatic focusing, whereas it does not in a non-focusing model. However, the effects of focusing can be mimicked in a non-focused simulation by introducing a free-escape boundary ahead of the shock close to the position where the particles will escape from the shock by focusing in a focused transport simulation. This provides a promising avenue for constructing computationally efficient codes that can model the particle emission from shocks.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140736490","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}
Predictions of coronal mass ejection (CME) propagation and impact in the heliosphere, in either research or operational settings, are usually performed by employing magnetohydrodynamic (MHD) models. Within such simulations, the CME ejecta is often described as a hydrodynamic pulse that lacks an internal magnetic field and is characterized by a spherical geometry---leading to the so-called cone CME model. White-light observations of CMEs in the corona, however, reveal that the morphology of these structures resembles more closely that of a croissant, i.e., exhibiting an elongated cross section of their front. It follows that, in space weather forecasts, the assumption of a spherical geometry may result in erroneous predictions of CME impacts in the heliosphere in terms of hit/miss and arrival time/speed, especially in the case of flank encounters. A spheroid CME model is expected to provide a more accurate description of the elongated morphology that is often observed in CMEs. In this paper, we describe the implementation and initial validation of the spheroid CME model within the MHD EUropean Heliospheric FORecasting Information Asset (EUHFORIA) code. We perform EUHFORIA simulations of an idealized CME as well as a "real'' event to compare the spheroidal model with the traditional cone one. We show how the initial ejecta geometry can lead to substantially different estimates in terms of CME impact, arrival time/speed, and geoeffectiveness, especially with increasing distance to the CME nose.
{"title":"The spheroid CME model in EUHFORIA","authors":"C. Scolini, E. Palmerio","doi":"10.1051/swsc/2024011","DOIUrl":"https://doi.org/10.1051/swsc/2024011","url":null,"abstract":"Predictions of coronal mass ejection (CME) propagation and impact in the heliosphere, in either research or operational settings, are usually performed by employing magnetohydrodynamic (MHD) models. Within such simulations, the CME ejecta is often described as a hydrodynamic pulse that lacks an internal magnetic field and is characterized by a spherical geometry---leading to the so-called cone CME model. White-light observations of CMEs in the corona, however, reveal that the morphology of these structures resembles more closely that of a croissant, i.e., exhibiting an elongated cross section of their front. It follows that, in space weather forecasts, the assumption of a spherical geometry may result in erroneous predictions of CME impacts in the heliosphere in terms of hit/miss and arrival time/speed, especially in the case of flank encounters. A spheroid CME model is expected to provide a more accurate description of the elongated morphology that is often observed in CMEs. In this paper, we describe the implementation and initial validation of the spheroid CME model within the MHD EUropean Heliospheric FORecasting Information Asset (EUHFORIA) code. We perform EUHFORIA simulations of an idealized CME as well as a \"real'' event to compare the spheroidal model with the traditional cone one. We show how the initial ejecta geometry can lead to substantially different estimates in terms of CME impact, arrival time/speed, and geoeffectiveness, especially with increasing distance to the CME nose.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140737928","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}
Alan Wood, Elizabeth E. Donegan-Lawley, Lasse B. N. Clausen, L. Spogli, Jaroslav Urbar, Yaqi Jin, Golnaz Shahtahmassebi, L. Alfonsi, James T. Rawlings, A. Cicone, Daria Kotova, C. Cesaroni, Per Hoeg, G. Dorrian, L. Nugent, S. Elvidge, D. Themens, María José Brazal Aragon, Pawel Wojtkiewicz, Wojciech J. Miloch
This work presents statistical models of the variability of plasma in the topside ionosphere based on observations made by the European Space Agency’s (ESA) Swarm satellites. The models were developed in the “Swarm Variability of Ionospheric Plasma” (Swarm-VIP) project within the European Space Agency's Swarm+4D-Ionosphere framework. The configuration of the Swarm satellites, their near-polar orbits and the data products developed, enable studies of the spatial variability of the ionosphere at multiple scale sizes. The statistical modelling technique of Generalised Linear Modelling was used to create models of both the electron density and measures of the variability of the plasma structures at horizontal spatial scales between 20 km and 100 km. Despite being developed using the Swarm data, the models provide predictions that are independent of these data. Separate models were created for low, middle, auroral and polar latitudes. The models make predictions based on heliogeophysical variables, which act as proxies for the solar and geomagnetic processes. The first and most significant term in the majority of the models was a proxy for solar activity. The most common second term varied with the latitudinal region. This was the Solar Zenith Angle (SZA) in the polar region, a measure of latitude in the auroral region, solar time in the mid-latitude region and a measure of latitude in the equatorial region. Other, less significant terms in the models covered a range of proxies for the solar wind, geomagnetic activity and location. In this paper the formulation, optimisation and evaluation of these models is discussed. The models show very little bias, with a mean error of zero to two decimal places in 14 out of 20 cases. The models capture some, but not all, of the trends present in the data, with Pearson correlation coefficients of up to 0.75 between the observations and the model predictions. The models also capture some, but not all, of the variability of the ionospheric plasma, as indicated by the precision, which ranged between 0.20 and 0.83. The addition of the thermospheric density as an explanatory variable in the models improved the precision in the polar and auroral regions. It is suggested that, if the thermosphere could be observed at a higher spatial resolution, then even more of the variability of the plasma structures could be captured by statistical models. The formulation and optimisation of the models are presented in this paper. The capability of the model in reproducing the expected climatological features of the topside ionosphere, in supporting GNSS-based ionospheric observations and the performance of the model against TIE-GCM, are provided in a companion paper (Spogli et al., 2023).
{"title":"Statistical Models of the Variability of Plasma in the Topside Ionosphere: 1. Development and Optimisation","authors":"Alan Wood, Elizabeth E. Donegan-Lawley, Lasse B. N. Clausen, L. Spogli, Jaroslav Urbar, Yaqi Jin, Golnaz Shahtahmassebi, L. Alfonsi, James T. Rawlings, A. Cicone, Daria Kotova, C. Cesaroni, Per Hoeg, G. Dorrian, L. Nugent, S. Elvidge, D. Themens, María José Brazal Aragon, Pawel Wojtkiewicz, Wojciech J. Miloch","doi":"10.1051/swsc/2024002","DOIUrl":"https://doi.org/10.1051/swsc/2024002","url":null,"abstract":"This work presents statistical models of the variability of plasma in the topside ionosphere based on observations made by the European Space Agency’s (ESA) Swarm satellites. The models were developed in the “Swarm Variability of Ionospheric Plasma” (Swarm-VIP) project within the European Space Agency's Swarm+4D-Ionosphere framework. The configuration of the Swarm satellites, their near-polar orbits and the data products developed, enable studies of the spatial variability of the ionosphere at multiple scale sizes.\u0000The statistical modelling technique of Generalised Linear Modelling was used to create models of both the electron density and measures of the variability of the plasma structures at horizontal spatial scales between 20 km and 100 km. Despite being developed using the Swarm data, the models provide predictions that are independent of these data. Separate models were created for low, middle, auroral and polar latitudes. The models make predictions based on heliogeophysical variables, which act as proxies for the solar and geomagnetic processes. The first and most significant term in the majority of the models was a proxy for solar activity. The most common second term varied with the latitudinal region. This was the Solar Zenith Angle (SZA) in the polar region, a measure of latitude in the auroral region, solar time in the mid-latitude region and a measure of latitude in the equatorial region. Other, less significant terms in the models covered a range of proxies for the solar wind, geomagnetic activity and location. In this paper the formulation, optimisation and evaluation of these models is discussed. The models show very little bias, with a mean error of zero to two decimal places in 14 out of 20 cases. The models capture some, but not all, of the trends present in the data, with Pearson correlation coefficients of up to 0.75 between the observations and the model predictions. The models also capture some, but not all, of the variability of the ionospheric plasma, as indicated by the precision, which ranged between 0.20 and 0.83. The addition of the thermospheric density as an explanatory variable in the models improved the precision in the polar and auroral regions. It is suggested that, if the thermosphere could be observed at a higher spatial resolution, then even more of the variability of the plasma structures could be captured by statistical models. The formulation and optimisation of the models are presented in this paper. The capability of the model in reproducing the expected climatological features of the topside ionosphere, in supporting GNSS-based ionospheric observations and the performance of the model against TIE-GCM, are provided in a companion paper (Spogli et al., 2023).","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139529951","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}
L. Spogli, Yaqi Jin, Jaroslav Urbar, Alan Wood, Elizabeth E. Donegan-Lawley, Lasse B. N. Clausen, Golnaz Shahtahmassebi, L. Alfonsi, James T. Rawlings, A. Cicone, Daria Kotova, C. Cesaroni, Per Hoeg, G. Dorrian, L. Nugent, S. Elvidge, D. Themens, María José Brazal Aragon, Pawel Wojtkiewicz, Wojciech J. Miloch
Statistical models of the variability of plasma in the topside ionosphere based on the Swarm data have been developed in the “Swarm Variability of Ionospheric Plasma” (Swarm-VIP) project within the European Space Agency's Swarm+4D-Ionosphere framework.. The models can predict the electron density, its gradients for three horizontal spatial scales – 20, 50 and 100 km – along the North-South direction and the level of the density fluctuations. Despite being developed by leveraging on Swarm data, the models provide predictions that are independent of these data, having a global coverage, fed by various parameters and proxies of the helio-geophysical conditions. Those features make the Swarm-VIP models useful for various purposes, which includes the possible support for already available ionospheric models and to proxy the effect of ionospheric irregularities of the medium scales that affect the signals emitted by Global Navigation Satellite Systems (GNSS). The formulation, optimisation and validation of the Swarm-VIP models are reported in Paper 1 (Wood et al., 2024). This paper describes the performance assessment of the models, by addressing their capability in reproducing the known climatological variability of the modelled quantities, and the ionospheric weather as depicted by ground-based GNSS, as a proxy for the ionospheric effect on GNSS signals. Additionally, we demonstrate that, under certain conditions, the model can better reproduce the ionospheric variability than a physics-based model, namely the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM).
{"title":"Statistical Models of the Variability of Ionospheric Plasma in the Topside Ionosphere: 2. Performance assessment","authors":"L. Spogli, Yaqi Jin, Jaroslav Urbar, Alan Wood, Elizabeth E. Donegan-Lawley, Lasse B. N. Clausen, Golnaz Shahtahmassebi, L. Alfonsi, James T. Rawlings, A. Cicone, Daria Kotova, C. Cesaroni, Per Hoeg, G. Dorrian, L. Nugent, S. Elvidge, D. Themens, María José Brazal Aragon, Pawel Wojtkiewicz, Wojciech J. Miloch","doi":"10.1051/swsc/2024003","DOIUrl":"https://doi.org/10.1051/swsc/2024003","url":null,"abstract":"Statistical models of the variability of plasma in the topside ionosphere based on the Swarm data have been developed in the “Swarm Variability of Ionospheric Plasma” (Swarm-VIP) project within the European Space Agency's Swarm+4D-Ionosphere framework.. The models can predict the electron density, its gradients for three horizontal spatial scales – 20, 50 and 100 km – along the North-South direction and the level of the density fluctuations. Despite being developed by leveraging on Swarm data, the models provide predictions that are independent of these data, having a global coverage, fed by various parameters and proxies of the helio-geophysical conditions. Those features make the Swarm-VIP models useful for various purposes, which includes the possible support for already available ionospheric models and to proxy the effect of ionospheric irregularities of the medium scales that affect the signals emitted by Global Navigation Satellite Systems (GNSS). The formulation, optimisation and validation of the Swarm-VIP models are reported in Paper 1 (Wood et al., 2024). This paper describes the performance assessment of the models, by addressing their capability in reproducing the known climatological variability of the modelled quantities, and the ionospheric weather as depicted by ground-based GNSS, as a proxy for the ionospheric effect on GNSS signals. Additionally, we demonstrate that, under certain conditions, the model can better reproduce the ionospheric variability than a physics-based model, namely the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM).","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139531888","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}
E. Palmerio, J. Luhmann, M. L. Mays, Ronald M. Caplan, D. Lario, Ian G. Richardson, Kathryn Whitman, Christina O. Lee, B. S'anchez-Cano, N. Wijsen, Yan Li, Carlota Cardoso, M. Pinto, D. Heyner, Daniel Schmid, H. Auster, David Fischer
Multi-spacecraft observations of solar energetic particle (SEP) events enable not only a for deeper understanding and development of particle acceleration and transport theories, but also provide important constraints for model validation efforts. However, because of computational limitations, a given physics-based SEP model is usually best-suited to capture a particular phase of an SEP event, rather than its whole development from onset through decay. For example, magnetohydrodynamic (MHD) models of the heliosphere often incorporate solar transients only at the outer boundary of their so-called coronal domain—usually set at a heliocentric distance of 20–30 R☉. This means that particle acceleration at CME-driven shocks is also computed from this boundary onwards, leading to simulated SEP event onsets that can be many hours later than observed, since shock waves can form much lower in the solar corona. In this work, we aim to improve the modelled onset of SEP events by inserting a "fixed source" of particle injection at the outer boundary of the coronal domain of the coupled WSA–Enlil 3D MHD model of the heliosphere. The SEP model that we employ for this effort is SEPMOD, a physics-based test-particle code based on a field line tracer and adiabatic invariant conservation. We apply our initial tests and results of SEPMOD's fixed-source option to the 2021 October 9 SEP event, which was detected at five well-separated locations in the inner heliosphere—Parker Solar Probe, STEREO-A, Solar Orbiter, BepiColombo, and near-Earth spacecraft.
{"title":"Improved modelling of SEP event onset within the WSA–Enlil–SEPMOD framework","authors":"E. Palmerio, J. Luhmann, M. L. Mays, Ronald M. Caplan, D. Lario, Ian G. Richardson, Kathryn Whitman, Christina O. Lee, B. S'anchez-Cano, N. Wijsen, Yan Li, Carlota Cardoso, M. Pinto, D. Heyner, Daniel Schmid, H. Auster, David Fischer","doi":"10.1051/swsc/2024001","DOIUrl":"https://doi.org/10.1051/swsc/2024001","url":null,"abstract":"Multi-spacecraft observations of solar energetic particle (SEP) events enable not only a for deeper understanding and development of particle acceleration and transport theories, but also provide important constraints for model validation efforts. However, because of computational limitations, a given physics-based SEP model is usually best-suited to capture a particular phase of an SEP event, rather than its whole development from onset through decay. For example, magnetohydrodynamic (MHD) models of the heliosphere often incorporate solar transients only at the outer boundary of their so-called coronal domain—usually set at a heliocentric distance of 20–30 R☉. This means that particle acceleration at CME-driven shocks is also computed from this boundary onwards, leading to simulated SEP event onsets that can be many hours later than observed, since shock waves can form much lower in the solar corona. In this work, we aim to improve the modelled onset of SEP events by inserting a \"fixed source\" of particle injection at the outer boundary of the coronal domain of the coupled WSA–Enlil 3D MHD model of the heliosphere. The SEP model that we employ for this effort is SEPMOD, a physics-based test-particle code based on a field line tracer and adiabatic invariant conservation. We apply our initial tests and results of SEPMOD's fixed-source option to the 2021 October 9 SEP event, which was detected at five well-separated locations in the inner heliosphere—Parker Solar Probe, STEREO-A, Solar Orbiter, BepiColombo, and near-Earth spacecraft.","PeriodicalId":17034,"journal":{"name":"Journal of Space Weather and Space Climate","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139534765","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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