scholarly journals Several special conditions in the solar wind fora supersubstorm appearance.

2020 ◽  
Author(s):  
I.V. Despirak ◽  
◽  
A.A. Lubchich ◽  
N.G. Kleimenova ◽  
◽  
...  
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Data Base ◽  
Space Weather ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Solar Wind Speed ◽  
Weather Conditions ◽  
The Other ◽  
Solar Wind Parameters

Analysis of the space weather conditions associated with supersubstorms (SSS) was carried out. Two magnetic storms, on 11 April and on 18 April 2001 have been studied and compared. During the first storm, there were registered twoevents of the supersubstorms with intensity of the SML index ~2000-3000 nT, whereas during the second storm there were observed two intense substorms with SML ~ 1500 nT. Solar wind conditions before appearance of the SSSs and intense substorms were compared. For this purpose, the OMNI data base, the catalog of large-scale solar wind phenomena and the data from the magnetic ground-based stations of the SuperMAG network (http://supermag.jhuapl.edu/) were combined. It was shown that the onsets of the SSS event were preceded by strong jumps in the dynamic pressure and density of the solar wind, which were observed against the background of the high solar wind speed and high values of the southern ВZcomponent of the IMF. Comparison with the usual substorms showed thatsome solar wind parameters were higher before SSSs, then before usual substorms: the dynamic pressure, the speed and the magnitude of IMF. On the other hand, the PC index values was the same for these all substorms, that leads to the conclusion about the possible independence of SSS appearance on the level of solar energy penetrated to the magnetosphere.

3D MHD study of the Earth magnetosphere response during extreme space weather conditions

2021 ◽  
Author(s):  
Jacobo Varela Rodriguez ◽  
Sacha A. Brun ◽  
Antoine Strugarek ◽  
Victor Réville ◽  
Filippo Pantellini ◽  
...  
Keyword(s):  
Solar Wind ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Main Sequence ◽  
Dynamic Pressure ◽  
Weather Conditions ◽  
The Sun ◽  
Earth Surface ◽  
The Earth ◽  
The Imf

<p><span>The aim of the study is to analyze the response of the Earth magnetosphere for various space weather conditions and model the effect of interplanetary coronal mass ejections. The magnetopause stand off distance, open-closed field lines boundary and plasma flows towards the planet surface are investigated. We use the MHD code PLUTO in spherical coordinates to perform a parametric study regarding the dynamic pressure and temperature of the solar wind as well as the interplanetary magnetic field intensity and orientation. The range of the parameters analyzed extends from regular to extreme space weather conditions consistent with coronal mass ejections at the Earth orbit. The direct precipitation of the solar wind on the Earth day side at equatorial latitudes is extremely unlikely even during super coronal mass ejections. For example, the SW precipitation towards the Earth surface for a IMF purely oriented in the Southward direction requires a IMF intensity around 1000 nT and the SW dynamic pressure above 350 nPa, space weather conditions well above super-ICMEs. The analysis is extended to previous stages of the solar evolution considering the rotation tracks from Carolan (2019). The simulations performed indicate an efficient shielding of the Earth surface 1100 Myr after the Sun enters in the main sequence. On the other hand, for early evolution phases along the Sun main sequence once the Sun rotation rate was at least 5 times faster (< 440 Myr), the Earth surface was directly exposed to the solar wind during coronal mass ejections (assuming today´s Earth magnetic field). Regarding the satellites orbiting the Earth, Southward and Ecliptic IMF orientations are particularly adverse for Geosynchronous satellites, partially exposed to the SW if the SW dynamic pressure is 8-14 nPa and the IMF intensity 10 nT. On the other hand, Medium orbit satellites at 20000 km are directly exposed to the SW during Common ICME if the IMF orientation is Southward and during Strong ICME if the IMF orientation is Earth-Sun or Ecliptic. The same way, Medium orbit satellites at 10000 km are directly exposed to the SW if a Super ICME with Southward IMF orientation impacts the Earth.</span></p><p>This work was supported by the project 2019-T1/AMB-13648 founded by the Comunidad de Madrid, grants ERC WholeSun, Exoplanets A and PNP. We extend our thanks to CNES for Solar Orbiter, PLATO and Meteo Space science support and to INSU/PNST for their financial support.</p>

scholarly journals Peculiar Current Solar-Minimum Structure of the Heliosphere

2009 ◽  
Vol 5 (H15) ◽  
pp. 484-487
Author(s):  
P. K. Manoharan
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Solar Minimum ◽  
Large Scale ◽  
Solar Wind Speed ◽  
Heliospheric Current Sheet ◽  
Coronal Density ◽  
Current Minimum ◽  
Similar Phase ◽  
The Magnetic Field

AbstractIn this paper, I review the results of 3-D evolution of the inner heliosphere over the solar cycle 23, based on observations of interplanetary scintillation (IPS) made at 327 MHz using the Ooty Radio Telescope. The large-scale features of solar wind speed and density turbulence of the current minimum are remarkably different from that of the previous cycle. The results on the solar wind density turbulence show that (1) the current solar minimum is experiencing a low level of coronal density turbulence, to a present value of ~50% lower than the previous similar phase, and (2) the scattering diameter of the corona has decreased steadily after the year 2003. The results on solar wind speed are consistent with the magnetic field strength at the poles and the warping of heliospheric current sheet.

Large-scale electron solar wind parameters of the inner heliosphere with Parker Solar Probe/FIELDS

2020 ◽  
Author(s):  
Karine Issautier ◽  
Mingzhe Liu ◽  
Michel Moncuquet ◽  
Nicole Meyer-Vernet ◽  
Milan Maksimovic ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Statistical Study ◽  
Solar Wind Speed ◽  
The Sun ◽  
Solar Wind Parameters ◽  
Power Law Index ◽  
Probe Mission ◽  
Inner Heliosphere

<p>We present in situ properties of electron density and temperature in the inner heliosphere obtained during the three first solar encounters at 35 solar radii of the Parker Solar Probe mission. These preliminary results, recently shown by Moncuquet et al., ApJS, 2020, are obtained from the analysis of the plasma quasi-thermal noise (QTN) spectrum measured by the radio RFS/FIELDS instrument along the trajectories extending between 0.5 and 0.17 UA from the Sun, revealing different states of the emerging solar wind, five months apart. The temperature of the weakly collisional core population varies radially with a power law index of about -0.8, much slower than adiabatic, whereas the temperature of the supra-thermal population exhibits a much flatter radial variation, as expected from its nearly collisionless state. These measured temperatures are close to extrapolations towards the Sun of Helios measurements.</p><p>We also present a statistical study from these in situ electron solar wind parameters, deduced by QTN spectroscopy, and compare the data to other onboard measurements. In addition, we focus on the large-scale solar wind properties. In particular, from the invariance of the energy flux, a direct relation between the solar wind speed and its density can be deduced, as we have already obtained based on Wind continuous in situ measurements (Le Chat et al., Solar Phys., 2012). We study this anti-correlation during the three first solar encounters of PSP.</p>

scholarly journals Even moderate geomagnetic pulsations can cause fluctuations of foF2 frequency of the auroral ionosphere

2020 ◽  
Author(s):  
Nadezda Yagova ◽  
Alexander Kozlovsky ◽  
Evgeny Fedorov ◽  
Olga Kozyreva
Keyword(s):  
Space Weather ◽  
Critical Frequency ◽  
Dynamic Pressure ◽  
Solar Wind Speed ◽  
Pressure Fluctuations ◽  
Weather Conditions ◽  
Geomagnetic Pulsations ◽  
Station Pair ◽  
Using Data ◽  
Magnetic Meridian

Abstract. Using data of the ionosonde in Sodankyla, (SOD, 67° N, 27° E, Finland), variations of the critical frequency of o-mode radiowave reflected from ionospheric F2 layer (foF2) in 1–5 mHz frequency range and their possible association with long period (Pc5/Pi3) geomagnetic pulsations are studied. For that, a technique of automatic detection of the foF2 critical frequency from an ionogram is developed and applied to daytime Pc5/Pi3 geomagnetic pulsations and foF2 fluctuations during several months of years 2014–2015 near the maximum of 24-th Solar cycle. The variations of foF2 are compared with the Pc5/Pi3 geomagnetic pulsations at SOD station, and the influence of pulsations' spatial scale is analyzed with the data of a station pair located at the same magnetic meridian but separated in latitude. The variations of foF2 are in the majority of cases decoupled from the geomagnetic pulsations on the ground. Meanwhile, the analysis of geomagnetic and foF2 variations show intervals with noticeable coherence for both horizontal components. These coherent pulsations are predominantly registered in the afternoon sector of the magnetic local time (MLT). Statistically, their spectral content, polarization and spatial distribution differ from averaged parameters of post-noon Pc5 pulsations. The pulsations, coherent to foF2 fluctuations, demonstrate features typical for Alfven field-line resonance. The analysis of space weather conditions favorable for the occurrence of coherent geomagnetic/foF2 pulsations show that these pulsations are registered mostly under moderately disturbed conditions. Comparison of space weather parameters for all the intervals analyzed and the intervals of high geomagnetic/foF2 coherence show that the latter correspond mostly to intermediate values of indexes of geomagnetic (Dst) and auroral (AE) activity, solar wind speed and dynamic pressure fluctuations.

scholarly journals Echo state network model for analyzing solar-wind effects on the AU and AL indices

2022 ◽  
Vol 40 (1) ◽  
pp. 11-22
Author(s):  
Shin'ya Nakano ◽  
Ryuho Kataoka
Keyword(s):  
Neural Network ◽  
Solar Wind ◽  
Wind Speed ◽  
Solar Wind Speed ◽  
Synthetic Data ◽  
Nonlinear Effects ◽  
Echo State Network ◽  
Solar Wind Density ◽  
Machine Learning Model ◽  
Solar Wind Parameters

Abstract. The properties of the auroral electrojets are examined on the basis of a trained machine-learning model. The relationships between solar-wind parameters and the AU and AL indices are modeled with an echo state network (ESN), a kind of recurrent neural network. We can consider this trained ESN model to represent nonlinear effects of the solar-wind inputs on the auroral electrojets. To identify the properties of auroral electrojets, we obtain various synthetic AU and AL data by using various artificial inputs with the trained ESN. The analyses of various synthetic data show that the AU and AL indices are mainly controlled by the solar-wind speed in addition to Bz of the interplanetary magnetic field (IMF) as suggested by the literature. The results also indicate that the solar-wind density effect is emphasized when solar-wind speed is high and when IMF Bz is near zero. This suggests some nonlinear effects of the solar-wind density.

scholarly journals Timing of the solar wind propagation delay between L1 and Earth based on machine learning

2021 ◽  
Author(s):  
Carsten Baumann ◽  
Aoife E. McCloskey
Keyword(s):  
Machine Learning ◽  
Solar Wind ◽  
Wind Speed ◽  
Space Weather ◽  
Solar Wind Speed ◽  
Propagation Delay ◽  
Learning Approach ◽  
Machine Learning Model ◽  
Machine Learning Approach ◽  
Gb Model

Erroneous GNSS positioning, failures in spacecraft operations and power outages due to geomagnetically induced currents  are severe threats originating from space weather. Having knowledge of potential impacts on modern society in advance is key for many end-user applications. This covers not only the timing of severe geomagnetic storms but also predictions of substorm onsets at polar latitudes. In this study we aim at contributing to the timing problem of space weather impacts and propose a new method to predict the solar wind propagation delay between Lagrangian point L1 and the Earth based on machine learning, specifically decision tree models. The propagation delay is measured from the identification of interplanetary discontinuities detected by the Advanced Composition Explorer (ACE) and their subsequent sudden commencements in the magnetosphere recorded by ground-based magnetometers. A database of the propagation delay has been constructed on this principle including 380 interplanetary shocks with data ranging from 1998 to 2018. The feature set of the machine learning approach consists of six features, namely the three components of each the solar wind speed and position of ACE around L1. The performance assessment of the machine learning model is examined on the basis of a 10-fold cross-validation. The machine learning results are compared to physics-based models, i.e., the flat propagation delay and the more sophisticated method based on the normal vector of solar wind discontinuities (vector delay). After hyperparameter optimization, the trained gradient boosting (GB) model is the best machine learning model among the tested ones. The GB model achieves an RMSE of 4.5 min with respect to the measured solar wind propagation delay and also outperforms the physical flat and vector delay models by 50 % and 15 % respectively. To increase the confidence in the predictions of the trained GB model, we perform a operational validation, provide drop-column feature importance and analyse the feature impact on the model output with Shapley values. The major advantage of the machine learning approach is its simplicity when it comes to its application. After training, values for the solar wind speed and spacecraft position from only one datapoint have to be fed into the algorithm for a good prediction.

scholarly journals TheKpindex and solar wind speed relationship: Insights for improving space weather forecasts

Space Weather ◽  
2013 ◽  
Vol 11 (6) ◽  
pp. 339-349 ◽  
Author(s):  
Heather A. Elliott ◽  
Jörg-Micha Jahn ◽  
David J. McComas
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Space Weather ◽  
Solar Wind Speed ◽  
Weather Forecasts

Space weather at Mercury as observed by the THEMIS telescope from Earth

2020 ◽  
Author(s):  
Melinda Dósa ◽  
Valeria Mangano ◽  
Anna Milillo ◽  
Stefano Massetti ◽  
Zsofia Bebesi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Space Weather ◽  
Dynamic Pressure ◽  
Weather Conditions ◽  
Angular Distance ◽  
Special Role ◽  
Solar Wind Magnetic Field

<p>The dynamic changes of Mercury’s Na exosphere are investigated here, in relation to space weather conditions. Sodium plays a special role in Mercury’s exosphere: due to its strong resonance D lines at 5890-95Å it has been observed and monitored by Earth-based telescopes for decades. Different and highly variable patterns of Na-emission have been identified. In addition to the release processes already studied extensively in the past, we aim here to investigate the following factors more in detail: the distance to the Sun, position in relation to the ecliptic plane and solar wind magnetic field strength and direction. In order to better investigate the relationship of these factors, we have studied the intensity of Na-emission as a function of solar wind dynamic pressure and TAA of Mercury by means of the extended dataset images collected from 2009 to 2013 by Earth-based observations performed at the THEMIS solar telescope. Solar wind velocity and density values are propagated with the magnetic lasso method to the position of Mercury from nearby space probes and compared with Na emission intensity. Data of either ACE or one of the two STEREO spacecraft were used, depending on which spacecraft had a smaller angular distance to Mercury. Single cases are studied qualitatively, and a longer-term quantitative comparison is shown, including further parameters (solar wind magnetic field strength and direction, TAA).</p>

scholarly journals Star Wars? Space Weather and Electricity Market: Evidence from China

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5281
Author(s):  
Tong Wu ◽  
Zhe You ◽  
Mengqi Gong ◽  
Jinhua Cheng
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Space Weather ◽  
Electricity Market ◽  
Power Plants ◽  
Consumption Rate ◽  
Solar Wind Speed ◽  
Electricity Consumption ◽  
Coal Consumption ◽  
Geomagnetic Index

This paper aims to investigate the impact of space weather on China’s electricity market. Based on data products provided by NOAA and the National Energy Administration in China, this paper uses solar wind velocity as a solar weather indicator and the disturbance storm time index as a magnetospheric weather indicator to match monthly Chinese electricity market data over 10 years. Based on a VAR model, we found that (1) space weather increases the demand for electricity in China, and solar wind speed and the geomagnetic index increase the electricity consumption of the whole of Chinese society, as space weather mainly increases the electricity consumption of the secondary and industrial sectors. (2) The geomagnetic index significantly promotes power station revenue. (3) Space weather is associated with increased energy consumption. The geomagnetic index significantly increases the coal consumption rate of fossil power plants in China, but the solar wind speed has nothing to do with the coal consumption rate of fossil power plants.

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