Origins of the Ambient Solar Wind: Implications for Space Weather

AbstractThe Sun, as an active star, is the driver of energetic phenomena that structure interplanetary space and affect planetary atmospheres. The effects of Space Weather on Earth and the solar system is of increasing importance as human spaceflight is preparing for lunar and Mars missions. This review is focusing on the solar perspective of the Space Weather relevant phenomena, coronal mass ejections (CMEs), flares, solar energetic particles (SEPs), and solar wind stream interaction regions (SIR). With the advent of the STEREO mission (launched in 2006), literally, new perspectives were provided that enabled for the first time to study coronal structures and the evolution of activity phenomena in three dimensions. New imaging capabilities, covering the entire Sun-Earth distance range, allowed to seamlessly connect CMEs and their interplanetary counterparts measured in-situ (so called ICMEs). This vastly increased our knowledge and understanding of the dynamics of interplanetary space due to solar activity and fostered the development of Space Weather forecasting models. Moreover, we are facing challenging times gathering new data from two extraordinary missions, NASA’s Parker Solar Probe (launched in 2018) and ESA’s Solar Orbiter (launched in 2020), that will in the near future provide more detailed insight into the solar wind evolution and image CMEs from view points never approached before. The current review builds upon the Living Reviews article by Schwenn from 2006, updating on the Space Weather relevant CME-flare-SEP phenomena from the solar perspective, as observed from multiple viewpoints and their concomitant solar surface signatures.

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Assessing the Quality of Models of the Ambient Solar Wind

Space Weather ◽

10.1029/2018sw002040 ◽

2018 ◽

Vol 16 (11) ◽

pp. 1644-1667 ◽

Cited By ~ 19

Author(s):

P. MacNeice ◽

L. K. Jian ◽

S. K. Antiochos ◽

C. N. Arge ◽

C. D. Bussy-Virat ◽

...

Keyword(s):

Solar Wind ◽

Ambient Solar Wind

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Space Weather, SuperDARN and the Tasmanian Tiger

Australian Journal of Physics ◽

10.1071/p96115 ◽

1997 ◽

Vol 50 (4) ◽

pp. 773 ◽

Cited By ~ 1

Author(s):

Raymond A. Greenwald

Keyword(s):

Solar Wind ◽

Electric Fields ◽

Space Weather ◽

Interplanetary Space ◽

Rapid Evolution ◽

Upper Atmosphere ◽

Global Network ◽

Pressure Gradients ◽

Earth’S Magnetosphere ◽

Earth's Magnetosphere

The plasma environment extending from the solar surface through interplanetary space to the outermost reaches of the Earth’s atmosphere and magnetic field is dynamic, often disturbed, and capable of harming humans and damaging manmade systems. Disturbances in this environment have been identified as space weather disturbances. At the present time there is growing interest in monitoring and predicting space weather disturbances. In this paper we present some of the difficulties involved in achieving this goal by comparing the processes that drive tropospheric-weather systems with those that drive space-weather systems in the upper atmosphere and ionosphere. The former are driven by pressure gradients which result from processes that heat and cool the atmosphere. The latter are driven by electric fields that result from interactions between the streams of ionised gases emerging from the Sun (solar wind) and the Earth’s magnetosphere. Although the dimensions of the Earth’s magnetosphere are vastly greater than those of tropospheric weather systems, the global space-weather response to changes in the solar wind is much more rapid than the response of tropospheric-weather systems to changing conditions. We shall demonstrate the rapid evolution of space-weather systems in the upper atmosphere through measurements with a global network of radars known as SuperDARN. We shall also describe how the SuperDARN network is evolving, including a newly funded Australian component known as the Tasman International Geospace Environmental Radar (TIGER).

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

10.5194/egusphere-egu21-1684 ◽

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

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&#180;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.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.

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The Sun

The Sun's Influence on Climate ◽

10.23943/princeton/9780691153834.003.0003 ◽

2015 ◽

Author(s):

Joanna D. Haigh ◽

Peter Cargill

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Atmosphere ◽

Space Weather ◽

Extreme Ultraviolet ◽

The Sun ◽

Base Level ◽

Earth’S Climate ◽

The Magnetic Field ◽

Terrestrial Magnetic Field

This chapter discusses how there are four general factors that contribute to the Sun's potential role in variations in the Earth's climate. First, the fusion processes in the solar core determine the solar luminosity and hence the base level of radiation impinging on the Earth. Second, the presence of the solar magnetic field leads to radiation at ultraviolet (UV), extreme ultraviolet (EUV), and X-ray wavelengths which can affect certain layers of the atmosphere. Third, the variability of the magnetic field over a 22-year cycle leads to significant changes in the radiative output at some wavelengths. Finally, the interplanetary manifestation of the outer solar atmosphere (the solar wind) interacts with the terrestrial magnetic field, leading to effects commonly called space weather.

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Explicit IMF By-dependence in geomagnetic activity

10.5194/egusphere-egu21-850 ◽

2021 ◽

Author(s):

Lauri Holappa ◽

Timo Asikainen ◽

Kalevi Mursula

Keyword(s):

Solar Wind ◽

Geomagnetic Activity ◽

Space Weather ◽

High Latitude ◽

Coupling Function ◽

Future Space ◽

Weather Modeling ◽

Southern High Latitude ◽

Imf Clock Angle ◽

The Imf

The interaction of the solar wind with the Earth&#8217;s magnetic &#64257;eld produces geomagnetic activity, which is critically dependent on the orientation of the interplanetary magnetic &#64257;eld (IMF). Most solar wind coupling functions quantify this dependence on the IMF orientation with the so-called IMF clock angle in a way, which is symmetric with respect to the sign of the By component. However, recent studies have shown that IMF By is an additional, independent driver of high-latitude geomagnetic activity, leading to higher (weaker) geomagnetic activity in Northern Hemisphere (NH) winter for By > 0 (By < 0). For NH summer the dependence on the By sign is reversed. We quantify the size of this explicit By-e&#64256;ect with respect to the solar wind coupling function, both for northern and southern high-latitude geomagnetic activity. We show that for a given value of solar wind coupling function, geomagnetic activity is about 40% stronger for By > 0 than for By < 0 in NH winter. We also discuss recent advances in the physical understanding of the By-effect. Our results highlight the importance of the IMF By-component for space weather and must be taken into account in future space weather modeling.

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A magnetodisc model service for planetary space weather studies

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2019022 ◽

2019 ◽

Vol 9 ◽

pp. A24

Author(s):

Nicholas Achilleos ◽

Patrick Guio ◽

Nicolas André ◽

Arianna M. Sorba

Keyword(s):

Solar Wind ◽

Space Weather ◽

Theoretical Models ◽

Plasma Pressure ◽

Space Environment ◽

Solar Wind Flow ◽

Physical Response ◽

Global Magnetic Field ◽

Upstream Solar Wind ◽

Azimuthal Current

Theoretical models play an important role in the Planetary Space Weather Services (PSWS) of the European Planetary Network (“Europlanet”), due to their ability to predict the physical response of magnetospheric environments to compressions or rarefactions in the upstream solar wind flow. We illustrate this aspect by presenting examples of some calculations done with the UCL Magnetodisc Model in both “Jupiter” and “Saturn” mode. Similar model outputs can now be provided via the PSWS MAGNETODISC service. For each planet’s space environment, we present example model outputs showing the effect of compressions and rarefactions on the global magnetic field, plasma pressure and azimuthal current density. As a simple illustration of the physics underlying these reference models, we quantify solar wind effects by comparing the “compressed” and “expanded” outputs to a nominal “average-state” model, reflecting more typical solar wind dynamic pressures. We also describe the implementation of the corresponding PSWS MAGNETODISC Service, through which similar outputs may be obtained by potential users.

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Seasonal and diurnal variations of geomagnetic activity and their role in Space Weather forecast

Canadian Journal of Physics ◽

10.1139/p01-049 ◽

2001 ◽

Vol 79 (6) ◽

pp. 907-920 ◽

Cited By ~ 6

Author(s):

W Lyatsky ◽

A M Hamza

Keyword(s):

Solar Wind ◽

Seasonal Variation ◽

Diurnal Variation ◽

Geomagnetic Activity ◽

Space Weather ◽

Weather Forecast ◽

Diurnal Variations ◽

Ionospheric Conductivity ◽

Solar Wind Parameters ◽

Possible Cause

A possible test for different models explaining the seasonal variation in geomagnetic activity is the diurnal variation. We computed diurnal variations both in the occurrence of large AE (auroral electrojet) indices and in the AO index. (AO is the auroral electrojet index that provides a measure of the equivalent zonal current.) Both methods show a similar diurnal variation in geomagnetic activity with a deep minimum around (37) UT (universal time) in winter and a shallower minimum near 59 UT in equinoctial months. The observed UT variation is consistent with the results of other scientists, but it is different from that expected from the RussellMcPherron mechanism proposed to explain the seasonal variation. It is suggested that the possible cause for the diurnal and seasonal variations may be variations in nightside ionospheric conductivity. Recent experimental results show an important role for ionospheric conductivity in particle acceleration and geomagnetic disturbance generation. They also show that low ionospheric conductivity is favorable to the generation of auroral and geomagnetic activity. The conductivity in conjugate nightside auroral zones (where substorm generation takes place) is minimum at equinoxes, when both auroral zones are in darkness. The low ionospheric conductivity at equinoxes may be a possible cause for the seasonal variation in the geomagnetic activity with maxima in equinoctial months. The diurnal variation in geomagnetic activity can be produced by the UT variation in the nightside ionospheric conductivity, which in winter and at equinoxes has a maximum around 45 UT that may lead to a minimum in geomagnetic activity at this time. We calculated the correlation patterns for the AE index versus solar-wind parameters inside and outside the (27) UT sector related to the minimum in geomagnetic activity. The correlation patterns appear different in these two sectors indeed, which is well consistent with the UT variation in geomagnetic activity. It also shows that it is possible to improve significantly the reliability of the Space Weather forecast by taking into account the dependence of geomagnetic activity not only on solar-wind parameters but also on UT and season. Our test shows that a simple account for the dependence of geomagnetic activity on UT can improve the reliability of the Space Weather forecast by at least 50% in the 27 UT sector in winter and equinoctial months. PACS No.: 91.25Le

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