Solar Wind Disturbances Research Articles

On the relationship of power lines outages caused by thunderstorms with Forbush decreases of cosmic rays

It is known that power lines outages often occur during thunderstorms. Here are the results of comparing of power lines outages in Yakutia from 2012 to 2018 with the database of Forbush-Storm events. This database contains information on geomagnetic storms and Forbush-decreases of cosmic rays from 1996 to 2018. There are 3 classes of the events: if these two ground-based manifestations of solar wind disturbances occur simultaneously (Forbush with Storm, F+S) or separately (Forbush without Storm, F-S and Storm without Forbush, S-F). For 7 years in the summer time, 73 power lines outages associated with thunderstorms were recorded. It is shown that in 56 cases these outages occurred simultaneously with (F-S) class, 16 – with (F+S) class, and only in 1 case lightning outages were not associated with Forbush-Storm events (-F-S). In 19 cases of (S-F) class, not a single lightning outage was recorded. This means that lightning outages on power lines are mainly associated with decreases in the cosmic rays intensity, and during geomagnetic storms, power transmission disruptions occur when storms are simultaneous with Forbush-decreases of cosmic rays. Apparently, this indicates the significance of the effect of cosmic rays on atmospheric electricity, and it is more significant than the effect of geomagnetic storms.

Influence of Interacting Solar Wind Disturbances on the Variations in Galactic Cosmic Rays

Influence of Interacting Solar Wind Disturbances on the Variations in Galactic Cosmic Rays

Radio bursts related geomagnetic storms with coronal mass ejections, x-ray solar flares and solar wind disturbances: a survey

Radio bursts related geomagnetic storms with coronal mass ejections, x-ray solar flares and solar wind disturbances: a survey

MMS Observations of Field Line Resonances Under Disturbed Solar Wind Conditions

AbstractWe report an observational study of magnetospheric field‐line resonances (FLRs) using multi‐point data from the Magnetospheric Multiscale (MMS) mission. We examine well‐defined FLR events in the frequency range ∼2–10 mHz observed under disturbed solar wind conditions, such as high‐speed solar wind streams and solar wind pressure pulses. We focus on their azimuthal wave numbers (m‐numbers) and spatial variations of the wave frequencies, and compare their occurrence characteristics and wave properties for insights into their energy sources. Under disturbed solar wind conditions, we have found supporting observations for both external and internal energy sources for the generation of FLRs. The FLRs associated with different energy sources appear to have different wave characteristics. Although mode coupling is very common (i.e., waves generally have both toroidal and poloidal components with variable relative amplitudes), our observations show that solar wind disturbances directly drive low‐m, toroidal mode dominated FLRs, but internal energy sources are inferred for high‐m, poloidal mode dominated FLRs. The frequencies of the toroidal and poloidal waves have different spatial variations as a function of the L‐value. The frequency of the toroidal mode waves can change continuously with L while the frequency of poloidal waves exhibits discrete spatial structure along L.

An integrated data-driven solar wind – CME numerical framework for space weather forecasting

The development of numerical models and tools which have operational space weather potential is an increasingly important area of research. This study presents recent Canadian efforts toward the development of a numerical framework for Sun-to-Earth simulations of solar wind disturbances. This modular three-dimensional (3D) simulation framework is based on a semi-empirical data-driven approach to describe the solar corona and an MHD-based description of the heliosphere. In the present configuration, the semi-empirical component uses the potential field source surface (PFSS) and Schatten current sheet (SCS) models to derive the coronal magnetic field based on observed magnetogram data. Using empirical relations, solar wind properties are associated with this coronal magnetic field. Together with a coronal mass ejection (CME) model, this provides inner boundary conditions for a global MHD model which is used to describe interplanetary propagation of the solar wind and CMEs. The proposed MHD numerical approach makes use of advanced numerical techniques. The 3D MHD code employs a finite-volume discretization procedure with limited piecewise linear reconstruction to solve the governing partial-differential equations. The equations are solved on a body-fitted hexahedral multi-block cubed-sphere mesh and an efficient iterative Newton method is used for time-invariant simulations and an explicit time-marching scheme is applied for unsteady cases. Additionally, an efficient anisotropic block-based refinement technique provides significant reductions in the size of the computational mesh by locally refining the grid in selected directions as dictated by the flow physics. The capabilities of the framework for accurately capturing solar wind structures and forecasting solar wind properties at Earth are demonstrated. Furthermore, a comparison with previously reported results and future space weather forecasting challenges are discussed.

Some Problems of Identifying Types of Large-Scale Solar Wind and Their Role in the Physics of the Magnetosphere: 4. The “Lost Driver”

One perturbed type of solar wind and magnetospheric disturbance drivers is the compression region in front of fast ICMEs—the Sheath region. In front of this region, an interplanetary shock is observed in approximately half of cases. However, the parameters and their time profiles in these two types of the Sheath region differ comparatively little. Therefore, the Sheath region without a shock is as geoeffective as the Sheath region with a shock: the Sheath region in the first case generated almost 10% of magnetic storms with a minimum Dst < –50 nT of all the magnetic storms for 1976–2017 with identified interplanetary drivers. Many authors do not analyze this driver (for this reason, we call it the “lost driver”); therefore, their studies contain incorrect conclusions on solar–terrestrial physics.

Two-step Dropouts of Radiation Belt Electron Phase Space Density Induced by a Magnetic Cloud Event

Abstract We report a two-step dropout event of radiation belt electron phase space density (PSD) induced by a typical magnetic cloud (MC) that drove an intense geomagnetic storm. The first and second steps of PSD dropout occurred, respectively, in the initial and main phases of the storm with a short-time partial recovery between the two dropouts. In this event, the initial phase after the sudden commencement lasted for near 21 hr, which gives an ideal opportunity to investigate the nature of the radiation belt electron dropout by isolating the main phase from any losses occurring during the initial phase. Detailed analysis shows that the first step of the dropout in the initial phase is likely associated with the magnetopause shadowing effect in combination with ultra-low frequency wave-induced outward transport caused by sustaining enhanced dynamic pressure activity before the MC. Comparably, the prolonged strong southward interplanetary magnetic field inside the MC that resulted in the storm main phase is supposed to play an important role in the second step of significant electron losses to the interplanetary space. Additionally, the partial recovery of electron PSD between the two steps of the dropout is possibly due to the acceleration processes via wave-particle interactions with whistler-mode chorus waves. Our study demonstrated that persistently enhanced solar wind dynamic pressure, which is frequently observed inside interplanetary coronal mass ejections and corotating interaction regions, can play an important role in modulating the radiation belt electron dynamics before the storm main phase driven by these solar wind disturbances.

Ring of Stations Method in Cosmic Rays Variations Research

For over 60 years, neutron monitors have been the main standard and high precision detectors for measuring cosmic rays with energy from 400 MeV to hundreds GeV. In order to obtain sufficiently complete information about the distribution of cosmic rays outside the magnetosphere, it is necessary to have a network of detectors spaced evenly enough around the globe. The ring of stations method is one of the most useful methods for studying the properties of the angular distribution of cosmic rays without expressing the cosmic ray intensity in terms of spherical harmonics. The method allows one to get the hourly longitude distribution of the cosmic ray intensity without modeling. The main objective of this work is to expand the use of the ring of stations method, as it is a convenient and useful method of studying cosmic ray variation. Using the ring of stations method, it is possible to study specific angular distributions of cosmic ray variation that are described poorly by the sum of the first spherical harmonics. The ring of stations method is primarily used to study Forbush decreases. Detailed descriptions of Forbush decrease investigation by the ring of stations method are presented in this study. The application of the method to the study of the precursors of Forbush decreases and cosmic rays behavior inside the solar wind disturbances is shown.

A Computationally Efficient, Time-Dependent Model of the Solar Wind for Use as a Surrogate to Three-Dimensional Numerical Magnetohydrodynamic Simulations

Near-Earth solar-wind conditions, including disturbances generated by coronal mass ejections (CMEs), are routinely forecast using three-dimensional, numerical magnetohydrodynamic (MHD) models of the heliosphere. The resulting forecast errors are largely the result of uncertainty in the near-Sun boundary conditions, rather than heliospheric model physics or numerics. Thus ensembles of heliospheric model runs with perturbed initial conditions are used to estimate forecast uncertainty. MHD heliospheric models are relatively cheap in computational terms, requiring tens of minutes to an hour to simulate CME propagation from the Sun to Earth. Thus such ensembles can be run operationally. However, ensemble size is typically limited to 10^{1} to 10^{2} members, which may be inadequate to sample the relevant high-dimensional parameter space. Here, we describe a simplified solar-wind model that can estimate CME arrival time in approximately 0.01 seconds on a modest desktop computer and thus enables significantly larger ensembles. It is a one-dimensional, incompressible, hydrodynamic model, which has previously been used for the steady-state solar wind, but it is here used in time-dependent form. This approach is shown to adequately emulate the MHD solutions to the same boundary conditions for both steady-state solar wind and CME-like disturbances. We suggest it could serve as a “surrogate” model for the full three-dimensional MHD models. For example, ensembles of 10^{5} to 10^{6} members can be used to identify regions of parameter space for more detailed investigation by the MHD models. Similarly, the simplicity of the model means it can be rewritten as an adjoint model, enabling variational data assimilation with MHD models without the need to alter their code. The model code is available as an Open Source download in the Python language.

Statistical characteristics of geomagnetic storm activity during solar cycle 24, 2009–2020

Urgency. The atmosphere and geospace are widely used as a radio channel in solving problems of radar, radio navigation, direction finding, radio communication, radio astronomy, and the remote sensing of the Earth from space or the near-earth environment from the surface of the planet. The parameters of the atmospheric-space radio channel are determined by the state of tropospheric and space weather, which is formed mainly by non-stationary processes on the Sun (solar storms) and partly by high-energy processes on the Earth and in the atmosphere. Geospace storms give rise to the strongest disturbances of the atmospheric-space radio channel, and it is important to note that these storms are diverse, so that no two storms are alike. At the same time, storms have both similar and individual features. Currently, there is insufficient knowledge about both of these features, and their study remains an urgent task of space geophysics and space radio physics. In particular, the identification of general patterns is advisable by performing a statistical analysis of a large number of storms. The aim of this work is to statistically analyze the parameters of the solar wind and geomagnetic field during the Solar Cycle 24 activity (2009–2020). Methods and Methodology. The parameters of the disturbed solar wind (number density nsw, velocity Vsw, and temperature Tsw), the disturbed values of the By- and Bz-components of the interplanetary magnetic field, which is the cause of magnetic storms on Earth, as well as the indices of geomagnetic activity (AE, Dst and Kp) are selected as source input to the study. In this paper, geomagnetic storms with Kр ≥ 5 or G1, G2, G3, and G4 geomagnetic storms are considered. In total, there were 153 storms with Kp ≥ 5. The time series of the nsw, Vsw, Tsw maximum values, of the By- and Bz-components, and of the AE, Dst and Kp indices, as well as of the Bz-component and the Dst index minimum values have been analyzed. Results. The main statistical characteristics of the parameters of the solar wind, interplanetary magnetic field, and of the geomagnetic field have been determined for 153 events that took place during Solar Cycle 24. Conclusions. The geomagnetic situation during Solar Cycle 24 was calmer than during Solar Cycle 23.

First Observations of the Disruption of the Earth's Foreshock Wave Field During Magnetic Clouds

AbstractThe foreshock, extending upstream of Earth's bow shock, is a region of intense electromagnetic wave activity and nonlinear phenomena, which can have global effects on geospace. It is also the first geophysical region encountered by solar wind disturbances journeying toward Earth. Here, we present the first observations of considerable modifications of the foreshock wave field during extreme events of solar origin called magnetic clouds. Cluster's multispacecraft data reveal that the typical quasi‐monochromatic foreshock waves can be completely replaced by a superposition of waves each with shorter correlation lengths. Global numerical simulations further confirm that the foreshock wave field is more intricate and organized at smaller scales. Ion measurements suggest that changes in shock‐reflected particle properties may cause these modifications of the wave field. This state of the foreshock is encountered only during extreme events at Earth, but intense magnetic fields are typical close to the Sun or other stars.

Revisiting the Strongest Martian X-Ray Halo Observed by XMM-Newton on 2003 November 19–21

Abstract On 2003 November 20–21, when the most intense geomagnetic storm during solar cycle 23 was observed at Earth, XMM-Newton recorded the strongest Martian X-ray halo hitherto. The strongest Martian X-ray halo has been suggested to be caused by the unusual solar wind, but no direct evidence has been given in previous studies. Here, we examined the Mars Global Surveyor (MGS) observations and found unambiguous evidence of unusual solar wind impact during that XMM-Newton observation: the whole induced magnetosphere of Mars was highly compressed. By comparing the solar wind dynamic pressure estimated at Mars from MGS observation and that predicted by different solar wind propagation models, it is further supported that the interplanetary condition during the XMM-Newton observation is not related to the quiet solar wind, but to solar wind disturbances with enhanced dynamic pressure, which is probably related to the interplanetary coronal mass ejection observed at Earth on 2003 November 20. A solar energetic particle event also impacted Mars during the XMM-Newton observation and lasted for several days. Its impact on the production of the X-ray emission from Mars may be worth investigating in the future.

Coordinated Interplanetary Scintillation Observations in Japan and Russia for Coronal Mass Ejection Events in Early September 2017

Interplanetary (IP) shocks traveling between the Sun and the Earth’s orbit were clearly detected in interplanetary scintillation (IPS) observations made at Toyokawa (Japan) and Pushchino (Russia), in association with two halo coronal mass ejections (CMEs) that occurred on 04 and 06 September 2017. Since the observation times at Toyokawa and Pushchino differ by about six hours, a combined analysis of the IPS data obtained at these sites enabled high-cadence tracking of the IP shock for one of the CME events. The plane-of-sky locations where the IP disturbances were observed at Toyokawa were generally consistent with those at Pushchino. The propagation speeds of IP shocks inferred from IPS observations were higher than the average speeds derived from the occurrence time of IP shocks at Earth. This difference was ascribed to the deceleration of the CME-driven shocks during propagation. The east–west asymmetry of the propagation speed of IP shocks was also revealed from IPS observations. Solar-wind disturbances moving at a speed significantly slower than the average speed of the IP shock were identified from the IPS observations of the 06 September 2017 halo CME event. A wide longitudinal extent of these slow disturbances was suggested by the fact they were observed not only west but also east of the Sun; i.e. the opposite side to the flare/CME site. The origin of the slow disturbances is considered to represent either wing portions of the highly warped IP shock or the post-shock dense materials.

On the Statistics of Acceleration and Loss of Relativistic Electrons in the Outer Radiation Belt: A Superposed Epoch Analysis

AbstractWe investigate the response of the outer Van Allen belt electrons to various types of solar wind and magnetospheric disturbances. We use electron phase space density calculations as well as concurrent Pc5 and chorus wave activity observations in the outer belt during the Van Allen Probes era to compare 20 electron enhancement and 8 depletion events. Results indicate that the combined effect of magnetopause shadowing and outward diffusion driven by Pc5 waves is present in both groups of events. Furthermore, in the case of enhancement events, the synergy of enhanced seed population levels and chorus activity—due to the enhanced substorm activity—can effectively replenish the losses of relativistic electrons, while inward diffusion can further accelerate them.

Generalized Additive Modeling Combined With Multiple Collinear for ICME Velocity Forecasting

AbstractOne of the main issues of space weather is the timely prediction of disturbed solar wind parameters at L1, especially caused by Coronal Mass Ejection (CME). Using the data from 170 front halo, flare‐associated CMEs, and in‐site solar wind data, an analysis of the Interplanetary Coronal Mass Ejection (ICME) peak velocity at L1 related to associated coronal parameters is performed. The statistical methods including the Generalized Additive Modeling (GAM) and Multiple Collinear (MC) have been applied to explain the underlying physical reasons and set up a new prediction model. Our results indicate that (1) X‐flare integral flux, CME linear velocity, and Acceleration observed on corona play key roles in ICME velocity, while other coronal parameters only present a weak correlation, such as the CME Mass and Angular Width, (2) the relationship between ICME velocity and CME Acceleration, as well as CME linear velocity, is nonstationary, and the ICME velocity will increase with the increasing CME Acceleration or linear velocity until saturation, and (3) MC is an effective method to improve the forecast model performance. Compared with 0.52 for only GAM, the correlation coefficient using GAM + MC reaches to 0.71. To further testify the prediction ability, the GAM + MC model results are compared with the Back‐Propagation network model and a typically empirical statistic relation proposed by Manoharan (2006, https://doi.org/10.1007/s11207-006-0100-y; their correlation coefficients and root mean squared errors are both roughly 0.6 and 100 km/s, respectively). It is found that the MC + GAM can upgrade the forecast at least over 10%.

System Identification and Data‐Driven Forecasting of AE Index and Prediction Uncertainty Analysis Using a New Cloud‐NARX Model

AbstractSevere geomagnetic storms caused by the solar wind disturbances have harmful influences on the operation of modern equipment and systems. The modeling and forecasting of AE index are extremely useful to understand the geomagnetic substorms. This study presents a novel cloud‐nonlinear autoregressive with exogenous input (NARX) model to predict AE index 1 hr ahead. The cloud‐NARX model provides AE index forecasting results, with a correlation coefficient of 0.87 on the data of whole year 2015. The benchmarks on the data of the two interested periods of 17–21 March 2015 and 22–26 June 2015 are presented. The presented model uses uncertainty “cloud” model and cloud transformation to quantify the uncertainty throughout the structure detection, parameter estimation, and model prediction. The new predicted band can be generated to forecast AE index with confidence interval. The proposed method provides a new way to evaluate the model based on uncertainty analysis, revealing the reliability of model, and visualize the bias of model prediction.

Comparison between statistical properties of Forbush decreases caused by solar wind disturbances from coronal mass ejections and coronal holes

In this paper, we compare Forbush decreases associated with solar wind disturbances from two types of solar sources: coronal mass ejections (sporadic Forbush decreases) and coronal holes (recurrent Forbush decreases). We used Forbush Effects and Interplanetary Disturbances database created and maintained by IZMIRAN and associated a certain amount of Forbush decreases in this database with interplanetary disturbances from coronal mass ejections (207 cases) as well as high speed streams from coronal holes (350 cases). Large number of events allows to apply statistical methods (distribution analysis, correlation analysis, multiple linear regression analysis) to compare those two groups of events. The results reveal that Forbush decreases associated with solar wind disturbances from the two types of solar sources differ significantly in their statistical characteristics: distributions, descriptive statistics, correlation and multiple regression coefficients.

Single ICMEs and Complex Transient Structures in the Solar Wind in 2010 – 2011

We analyzed statistics, solar sources and properties of interplanetary coronal mass ejections (ICMEs) in the solar wind. In comparison with the first eight years of Cycle 23, during the same period of Cycle 24 the yearly numbers of ICMEs were less correlated with the flare numbers (0.68 vs 0.78) and sunspot numbers (0.66 vs 0.81), whereas the ICME correlation with coronal mass ejections (CMEs) was higher (0.77 vs 0.70). For the period January 2010 -- August 2011, we identified solar sources of the ICMEs included in the Richardson and Cane list. The solar sources of ICME were determined from coronagraph observations of the Earth-directed CMEs supplemented by modeling of their propagation in the heliosphere using the kinematic models and the WSA Enlil Cone MHD-based model. A detailed analysis of the ICME solar sources in the period under study showed that in 11 cases out of 23 the observed ICME might be associated with two or more sources. In cases of multiple-source events, the resulting solar wind disturbances may be described as complex (merged) structures occurred due to the stream interactions with properties depending on the type of participating streams. As a reliable marker for identification of interacting streams and their sources, we used the plasma ion composition, as it becomes frozen in the low corona and remains unchanged in the heliosphere. According to the ion composition signatures, we classified these cases into three types: complex ejecta originating from weak and strong CME-CME interactions, as well as merged interaction regions originating from the CME-high-speed stream interactions. We described temporal profiles of the ion composition for the single-source and multi-source solar wind structures and compared them with the ICME signatures determined from the kinematic and magnetic field parameters of the solar wind.

New Method to Calculate the Time Variation of the Force Field Parameter

AbstractGalactic cosmic rays (CRs) entering the heliosphere are affected by interplanetary magnetic fields and solar wind disturbances resulting in the modulation of the CR total flux observed in the inner heliosphere. The so‐called force field model is often used to compute the galactic CR spectrum modulated by the solar activity due to the fact that it characterizes this process by only one parameter (the modulation potential, ϕ). In this work, we present two types of an empirical simplification (ES) method used to reconstruct the time variation of the modulation potential (Δϕ). Our ES offers a simple and fast alternative to compute the Δϕ at any desired time. The first ES type is based on the empirical fact that the dependence between Δϕ and neutron monitor (NM) count rates can be parameterized by a second‐degree polynomial. The second ES type is based on the assumption that there is a inverse relation between Δϕ and NM count rates. We report the parameters found for the two types, which may be used to compute Δϕ for some NMs in a very fast and efficient way. In order to test the validity of the proposed ES, we compare our results with Δϕ obtained from literature. Finally, we apply our method to obtain the proton and helium spectra of primary CRs near the Earth at four randomly selected times.

Anticipated electrical environment at Phobos: Nominal and solar storm conditions

A passing coronal mass ejection (CME) will manifest a different response at an airless body compared to a magnetized planet. Specifically, because the regolith-rich surfaces of airless bodies are directly exposed to the variations in the plasma flow, the surfaces are found to undergo anomalous surface charging during the passing of CME fast plasma events. In this study, we model the surface charging expected at Phobos for nominal solar wind conditions and also those associated with disturbed solar wind conditions during the passage of a CME similar to that observed by MAVEN at Mars in early March 2015. We use an ambipolar diffusion model to examine the development of the trailing wake/void in the plasma flow behind Phobos and the formation of mini-wakes within obstruction regions like Stickney Crater. We also consider the roving of an astronaut in Stickney Crater for Phobos positioned near 10h Local Time relative to Mars. We examine the plasma dissipation of the collected astronaut charge from contact electrification with the regolith.