Bibliography

Plasma-neutral gas interactions in various space environments: Assessment beyond simplified approximations as a Voyage 2050 theme

In the White Paper, submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we present the importance of advancing our knowledge of plasma-neutral gas interactions, and of deepening our understanding of the partially ionized environments that are ubiquitous in the upper atmospheres of planets and moons, and elsewhere in space. In future space missions, the above task requires addressing the following fundamental questions: (A) How and by how much do plasma-neutral gas interactions influence the re-distribution of externally provided energy to the composing species? (B) How and by how much do plasma-neutral gas interactions contribute toward the growth of heavy complex molecules and biomolecules? Answering these questions is an absolute prerequisite for addressing the long-standing questions of atmospheric escape, the origin of biomolecules, and their role in the evolution of planets, moons, or comets, under the influence of energy sources in the form of electromagnetic and corpuscular radiation, because low-energy ion-neutral cross-sections in space cannot be reproduced quantitatively in laboratories for conditions of satisfying, particularly, (1) low-temperatures, (2) tenuous or strong gradients or layered media, and (3) in low-gravity plasma. Measurements with a minimum core instrument package (\textless 15 kg) can be used to perform such investigations in many different conditions and should be included in all deep-space missions. These investigations, if specific ranges of background parameters are considered, can also be pursued for Earth, Mars, and Venus.

Yamauchi, Masatoshi; De Keyser, Johan; Parks, George; Oyama, Shin-ichiro; Wurz, Peter; Abe, Takumi; Beth, Arnaud; Daglis, Ioannis; Dandouras, Iannis; Dunlop, Malcolm; Henri, Pierre; Ivchenko, Nickolay; Kallio, Esa; Kucharek, Harald; Liu, Yong; Mann, Ingrid; Marghitu, Octav; Nicolaou, Georgios; Rong, Zhaojin; Sakanoi, Takeshi; Saur, Joachim; Shimoyama, Manabu; Taguchi, Satoshi; Tian, Feng; Tsuda, Takuo; Tsurutani, Bruce; Turner, Drew; Ulich, Thomas; Yau, Andrew; Yoshikawa, Ichiro;

Published by: Experimental Astronomy      Published on: mar

YEAR: 2022     DOI: 10.1007/s10686-022-09846-9

Collision cross-section; Future missions; Low-energy; Neutral gas; Plasma; Voyage 2050

The physics of space weather/solar-terrestrial physics (STP): what we know now and what the current and future challenges are

Major geomagnetic storms are caused by un-usually intense solar wind southward magnetic fields thatimpinge upon the Earth\textquoterights magnetosphere (Dungey, 1961).How can we predict the occurrence of future interplanetary events? Do we currently know enough of the underlying physics and do we have sufficient observations of solar wind phenomena that will impinge upon the Earth\textquoterights magnetosphere? We view this as the most important challenge in space weather. We discuss the case for magnetic clouds (MCs), interplanetary sheaths upstream of interplanetary coronal mass ejections (ICMEs), corotating interactionregions (CIRs) and solar wind high-speed streams (HSSs).The sheath- and CIR-related magnetic storms will be difficult to predict and will require better knowledge of the slow solar wind and modeling to solve. For interplanetaryspace weather, there are challenges for understanding the fluences and spectra of solar energetic particles (SEPs). This will require better knowledge of interplanetary shock properties as they propagate and evolve going from the Sun to1 AU (and beyond), the upstream slow solar wind and energetic \textquotedblleftseed\textquotedblright particles. Dayside aurora, triggering of night-side substorms, and formation of new radiation belts can all be caused by shock and interplanetary ram pressure impingements onto the Earth\textquoterights magnetosphere. The acceleration and loss of relativistic magnetospheric \textquotedblleftkiller\textquotedblright electronsand prompt penetrating electric fields in terms of causingpositive and negative ionospheric storms are reasonably well understood, but refinements are still needed. The forecasting of extreme events (extreme shocks, extreme solar energeticparticle events, and extreme geomagnetic storms (Carrington events or greater)) are also discussed. Energetic particle precipitation into the atmosphere and ozone destructionare briefly discussed. For many of the studies, the Parker Solar Probe, Solar Orbiter, Magnetospheric Multiscale Mission(MMS), Arase, and SWARM data will be useful.

Tsurutani, Bruce; Lakhina, Gurbax; Hajra, Rajkumar;

Published by: Nonlinear Processes in Geophysics      Published on: 01/2020

YEAR: 2020     DOI: 10.5194/npg-27-75-2020

Space weather forecasting: What we know now and what are the current and future challenges

Geomagnetic storms are caused by solar wind southward magnetic fields that impinge upon the Earth’s magnetosphere (Dungey, 1961). How can we forecast the occurrence of these interplanetary events? We view this as the most important challenge in Space Weather. We discuss the case for magnetic clouds (MCs), interplanetary sheaths upstream of ICMEs, corotating interaction regions (CIRs) and high speed streams (HSSs). The sheath- and CIR-related magnetic storms will be difficult to predict and will require better knowledge of the slow solar wind and modeling to solve.

Tsurutani, Bruce; Lakhina, Gurbax; Hajra, Rajkumar;

Published by: Nonlinear Processes Geophys. Discuss      Published on:

YEAR: 2019     DOI:

Solar wind driving of ionosphere-thermosphere responses in three storms near St. Patrick's Day in 2012, 2013, and 2015

We identify interplanetary plasma regions associated with three intense interplanetary coronal mass ejections (ICMEs)-driven geomagnetic storm intervals which occurred around the same time of the year: day of year 74\textendash79 (March) of 2012, 2013, and 2015. We show that differences in solar wind drivers lead to different dynamical ionosphere-thermosphere (IT) responses and to different preconditioning of the IT system. We introduce a new hourly based global metric for average low-latitude and northern middle-latitude vertical total electron content responses in the morning, afternoon, and evening local time ranges, derived from measurements from globally distributed Global Navigation Satellite System ground stations. Our novel technique of estimating nitric oxide (NO) cooling radiation in 11\textdegree latitudinal zones is based on Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) measurements. The thermospheric cooling throughout the storm phases is studied with this high latitudinal resolution for the first time. Additionally, TIMED/Global Ultraviolet Imager (GUVI) observations of the dynamical response of the thermospheric composition (O/N₂ ratio) are utilized to study negative ionospheric storm effects. Based on these data sets, we describe and quantify distinct IT responses to driving by ICME sheaths, magnetic clouds, coronal loop remnants, plasma discontinuities, and high-speed streams following ICMEs. Our analysis of coupling functions indicates strong connection between coupling with the solar wind and IT system response in ICME-type storms and also some differences. Knowledge of interplanetary features is crucial for understanding IT storm dynamics.

Verkhoglyadova, O.; Tsurutani, B.; Mannucci, A.; Mlynczak, M.; Hunt, L.; Paxton, L.; Komjathy, A.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 07/2016

YEAR: 2016     DOI: 10.1002/jgra.v121.910.1002/2016JA022883

Heliosphere-ionosphere-thermosphere coupling and energy budget in geomagnetic storms

1. Solar irradiance: F10. 7 2. High-latitude electric and magnetic field potential patterns and field-aligned currents (FAC): empirical Weimer05 model (Weimer, 2005), can use AMIE input

Verkhoglyadova, OP; Mannucci, AJ; Meng, X; Komjathy, A; Mlynczak, MG; Hunt, LA; Tsurutani, BT;

Published by:       Published on:

YEAR: 2016     DOI:

Use of radio occultation to probe the high-latitude ionosphere

We have explored the use of COSMIC data to provide valuable scientific information on the ionospheric impacts of energetic particle precipitation during geomagnetic storms. Ionospheric electron density in the E region, and hence ionospheric conductivity, is significantly altered by precipitating particles from the magnetosphere. This has global impacts on the thermosphere\textendashionosphere because of the important role of conductivity on high-latitude Joule heating. Two high-speed stream (HSS) and two coronal mass ejection (CME) storms are examined with the COSMIC data. We find clear correlation between geomagnetic activity and electron density retrievals from COSMIC. At nighttime local times, the number of profiles with maximum electron densities in the E layer (below 200 km altitude) is well correlated with geomagnetic activity. We interpret this to mean that electron density increases due to precipitation are captured by the COSMIC profiles. These "E-layer-dominant ionosphere" (ELDI) profiles have geomagnetic latitudes that are consistent with climatological models of the auroral location. For the two HSS storms that occurred in May of 2011 and 2012, a strong hemispheric asymmetry is observed, with nearly all the ELDI profiles found in the Southern, less sunlit, Hemisphere. Stronger aurora and precipitation have been observed before in winter hemispheres, but the degree of asymmetry deserves further study. For the two CME storms, occurring in July and November of 2012, large increases in the number of ELDI profiles are found starting in the storm\textquoterights main phase but continuing for several days into the recovery phase. Analysis of the COSMIC profiles was extended to all local times for the July 2012 CME storm by relaxing the ELDI criterion and instead visually inspecting all profiles above 50\textdegree magnetic latitude for signatures of precipitation in the E region. For 9 days during the July 2012 period, we find a signature of precipitation occurs nearly uniformly in local time, although the magnitude of electron density increase may vary with local time. The latitudinal extent of the precipitation layers is generally consistent with auroral climatology. However, after the storm main phase on 14 July 2012 the precipitation tended to be somewhat more equatorward than the climatology (by about 5\textendash10\textdegree latitude) and equatorward of the auroral boundary data acquired from the SSUSI sensor onboard the F18 DMSP satellite. We conclude that, if analyzed appropriately, high-latitude COSMIC profiles have the potential to contribute to our understanding of MI coupling processes and extend and improve existing models of the auroral region.

Mannucci, A.; Tsurutani, B.; Verkhoglyadova, O.; Komjathy, A.; Pi, X.;

Published by: Atmospheric Measurement Techniques      Published on: 07/2015

YEAR: 2015     DOI: 10.5194/amt-8-2789-2015

Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period

This paper presents an overview of results obtained during the CAWSES-II period on the short-term variability of the Sun and how it affects the near-Earth space environment. CAWSES-II was planned to examine the behavior of the solar-terrestrial system as the solar activity climbed to its maximum phase in solar cycle 24. After a deep minimum following cycle 23, the Sun climbed to a very weak maximum in terms of the sunspot number in cycle 24 (MiniMax24), so many of the results presented here refer to this weak activity in comparison with cycle 23. The short-term variability that has immediate consequence to Earth and geospace manifests as solar eruptions from closed-field regions and high-speed streams from coronal holes.

Gopalswamy, Nat; Tsurutani, Bruce; Yan, Yihua;

Published by: Progress in Earth and Planetary Science      Published on:

YEAR: 2015     DOI: 10.1186/s40645-015-0043-8

Solar wind driving of ionosphere-thermosphere responses during three storms on St. Patrick's Day.

Verkhoglyadova, Olga; Tsurutani, Bruce; Mannucci, Anthony; Komjathy, Attila; Mlynczak, Martin; Hunt, Linda; Paxton, Larry;

Published by:       Published on:

YEAR: 2015     DOI:

Interplanetary magnetic field By control of prompt total electron content increases during superstorms

Large magnitude increases in ionospheric total electron content (TEC) that occur over 1\textendash3\ h on the dayside are a significant manifestation of the main phases of superstorms. For the largest superstorms of solar cycle 23 (based on the Dst index), ground networks of GPS receivers measured peak total electron content increases greater than a factor of 2 relative to quiet time TEC averaged over the broad latitude band \textpm40\textdegree for local times 1200\textendash1600\ LT. Near 30\textdegree latitude, the Halloween storms of October 29\textendash30, 2003 appeared to produce storm-time TEC exceeding quiet time values by a factor of 5 within 2\textendash3\ h of storm onset, at 1300\ LT. The physical cause of these large positive phase ionospheric storms is usually attributed to prompt penetration electric fields (PPEFs) initiated by Region 1 current closure through the ionosphere ( Nopper and Carovillano, 1978 mechanism). An unresolved question is what determines variation of the TEC response for different superstorms. It has been suggested that the cross polar cap potential and Region 1 currents are significant factors in determining PPEF in the equatorial ionosphere, which are related to the solar wind reconnection electric field estimated by Kan\textendashLee and others. In this paper, we show evidence that suggests B_y may be a significant factor controlling the TEC response during the main phase of superstorms. We analyzed the interplanetary conditions during the period that TEC was increasing for eight superstorms. We find that increasing daytime TEC during superstorms only occurs for large reconnection electric fields when B_y magnitude is less than B_z. The data suggest that B_z is a far more important factor in the TEC response than the reconnection electric field. We also find that TEC decreases following its peak storm-time value for two superstorms, even though B_z remains large and B_y magnitudes are less than B_z. Such decreases during the geomagnetic disturbance may indicate the role of magnetospheric shielding currents, or of changes in the thermosphere that have developed over the prolonged period of large solar wind electric field. Further analysis is warranted covering a wider range of storm intensities on the role of B_y in affecting the daytime TEC response for a range of storm intensities.

Mannucci, A.J.; Crowley, G.; Tsurutani, B.T.; Verkhoglyadova, O.P.; Komjathy, A.; Stephens, P.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 08/2014

YEAR: 2014     DOI: 10.1016/j.jastp.2014.01.001

Geomagnetic storms; Ionosphere

Ionospheric TEC, thermospheric cooling and $\Sigma$ [O/N2] compositional changes during the 6--17 March 2012 magnetic storm interval (CAWSES II)

A series of four geomagnetic storms (the minimum SYM-H~-148\ nT) occurred during the March 6\textendash17, 2012 in the ascending phase of the solar cycle 24. This interval was selected by CAWSES II for its campaign. The GPS total electron content (TEC) database and JPL\textquoterights Global Ionospheric Maps (GIM) were used to study vertical TEC (VTEC) for different local times and latitude ranges. The largest response to geomagnetic activity is shown in increases of the low-latitude dayside VTEC. Several GPS sites feature post-afternoon VTEC \textquotedblleftbite-outs\textquotedblright. During Sudden Impulse (SI⁺) event on March 8th a peak daytime VTEC restores to about quiet-time values. It is shown that the TIMED/SABER zonal flux of nitric oxide (NO) infrared cooling radiation correlates well with auroral heating. A factor of ~5 cooling increase is noted in some storms. The cooling radiation intensifies in the auroral zone and spreads towards the equator. Effects of the storm appear at lower latitudes ~18.6\ h later. The column density ratio Σ[O/N₂] is analyzed based on TIMED/GUVI measurements. Both increases (at low latitudes) and decreases (from auroral to middle latitudes) in the ratio occurs during the geomagnetic storms. We suggest that the column density ratio could be enhanced at low to middle latitudes on the dayside partially due to the superfountain effect (atomic oxygen uplift due to ion-neutral drag). It is suggested that decreases in the Σ[O/N₂] ratio at high to middle-latitudes may be caused by high thermospheric temperatures. During SI⁺s, there is an increase in Σ[O/N₂] ratio at auroral latitudes.

Verkhoglyadova, O.P.; Tsurutani, B.T.; Mannucci, A.J.; Mlynczak, M.G.; Hunt, L.A.; Paxton, L.J.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 08/2014

YEAR: 2014     DOI: 10.1016/j.jastp.2013.11.009

Geomagnetic storms; Ionosphere; thermosphere

Solar filament impact on 21 January 2005: Geospace consequences

On 21 January 2005, a moderate magnetic storm produced a number of anomalous features, some seen more typically during superstorms. The aim of this study is to establish the differences in the space environment from what we expect (and normally observe) for a storm of this intensity, which make it behave in some ways like a superstorm. The storm was driven by one of the fastest interplanetary coronal mass ejections in solar cycle 23, containing a piece of the dense erupting solar filament material. The momentum of the massive solar filament caused it to push its way through the flux rope as the interplanetary coronal mass ejection decelerated moving toward 1 AU creating the appearance of an eroded flux rope (see companion paper by Manchester et al. (2014)) and, in this case, limiting the intensity of the resulting geomagnetic storm. On impact, the solar filament further disrupted the partial ring current shielding in existence at the time, creating a brief superfountain in the equatorial ionosphere\textemdashan unusual occurrence for a moderate storm. Within 1 h after impact, a cold dense plasma sheet (CDPS) formed out of the filament material. As the interplanetary magnetic field (IMF) rotated from obliquely to more purely northward, the magnetotail transformed from an open to a closed configuration and the CDPS evolved from warmer to cooler temperatures. Plasma sheet densities reached tens per cubic centimeter along the flanks\textemdashhigh enough to inflate the magnetotail in the simulation under northward IMF conditions despite the cool temperatures. Observational evidence for this stretching was provided by a corresponding expansion and intensification of both the auroral oval and ring current precipitation zones linked to magnetotail stretching by field line curvature scattering. Strong Joule heating in the cusps, a by-product of the CDPS formation process, contributed to an equatorward neutral wind surge that reached low latitudes within 1\textendash2 h and intensified the equatorial ionization anomaly. Understanding the geospace consequences of extremes in density and pressure is important because some of the largest and most damaging space weather events ever observed contained similar intervals of dense solar material.

Kozyra, J.; Liemohn, M.; Cattell, C.; De Zeeuw, D.; Escoubet, C.; Evans, D.; Fang, X.; Fok, M.-C.; Frey, H.; Gonzalez, W.; Hairston, M.; Heelis, R.; Lu, G.; Manchester, W.; Mende, S.; Paxton, L.; Rastaetter, L.; Ridley, A.; Sandanger, M.; Soraas, F.; Sotirelis, T.; Thomsen, M.; Tsurutani, B.; Verkhoglyadova, O.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 07/2014

YEAR: 2014     DOI: 10.1002/2013JA019748

cold dense plasma sheet; Equatorial anomaly; magnetotail; precipitation; prompt penetration electric field; solar filament

Variability of ionospheric TEC during solar and geomagnetic minima (2008 and 2009): external high speed stream drivers

We study solar wind\textendashionosphere coupling through the late declining phase/solar minimum and geomagnetic minimum phases during the last solar cycle (SC23) \textendash 2008 and 2009. This interval was characterized by sequences of high-speed solar wind streams (HSSs). The concomitant geomagnetic response was moderate geomagnetic storms and high-intensity, long-duration continuous auroral activity (HILDCAA) events. The JPL Global Ionospheric Map (GIM) software and the GPS total electron content (TEC) database were used to calculate the vertical TEC (VTEC) and estimate daily averaged values in separate latitude and local time ranges. Our results show distinct low- and mid-latitude VTEC responses to HSSs during this interval, with the low-latitude daytime daily averaged values increasing by up to 33 TECU (annual average of ~20 TECU) near local noon (12:00 to 14:00 LT) in 2008. In 2009 during the minimum geomagnetic activity (MGA) interval, the response to HSSs was a maximum of ~30 TECU increases with a slightly lower average value than in 2008. There was a weak nighttime ionospheric response to the HSSs. A well-studied solar cycle declining phase interval, 10\textendash22 October 2003, was analyzed for comparative purposes, with daytime low-latitude VTEC peak values of up to ~58 TECU (event average of ~55 TECU). The ionospheric VTEC changes during 2008\textendash2009 were similar but ~60\% less intense on average. There is an evidence of correlations of filtered daily averaged VTEC data with Ap index and solar wind speed.

We use the infrared NO and CO₂ emission data obtained with SABER on TIMED as a proxy for the radiation balance of the thermosphere. It is shown that infrared emissions increase during HSS events possibly due to increased energy input into the auroral region associated with HILDCAAs. The 2008\textendash2009 HSS intervals were ~85\% less intense than the 2003 early declining phase event, with annual averages of daily infrared NO emission power of ~ 3.3 \texttimes 10¹⁰ W and 2.7 \texttimes 10¹⁰ W in 2008 and 2009, respectively. The roles of disturbance dynamos caused by high-latitude winds (due to particle precipitation and Joule heating in the auroral zones) and of prompt penetrating electric fields (PPEFs) in the solar wind\textendashionosphere coupling during these intervals are discussed. A correlation between geoeffective interplanetary electric field components and HSS intervals is shown. Both PPEF and disturbance dynamo mechanisms could play important roles in solar wind\textendashionosphere coupling during prolonged (up to days) external driving within HILDCAA intervals.

Verkhoglyadova, O.; Tsurutani, B.; Mannucci, A.; Mlynczak, M.; Hunt, L.; Runge, T.;

Published by: Annales Geophysicae      Published on: 01/2013

YEAR: 2013     DOI: 10.5194/angeo-31-263-2013

Ionosphere; Magnetospheric physics; Storms; substorms

Comparison of Ionospheric and Thermospheric Effects During Two High Speed Stream Events

Verkhoglyadova, OP; Tsurutani, B; Mannucci, AJ; Paxton, L; Mlynczak, MG; Hunt, LA; Echer, E;

Published by:       Published on:

YEAR: 2013     DOI:

Ionospheric VTEC and thermospheric infrared emission dynamics during corotating interaction region and high-speed stream intervals at solar minimum: 25 March to 26 April 2008

Verkhoglyadova, O.; Tsurutani, B.; Mannucci, A.; Mlynczak, M.; Hunt, L.; Komjathy, A.; Runge, T.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2011

YEAR: 2011     DOI: 10.1029/2011JA016604

Local time dependence of the prompt ionospheric response for the 7, 9, and 10 November 2004 superstorms

We investigate the effects of penetration electric fields, meridional thermospheric neutral winds, and composition perturbation zones (CPZs) on the distribution of low-latitude plasma during the 7\textendash11 November 2004 geomagnetic superstorm. The impact on low-latitude plasma was assessed using total electron content (TEC) measurements from a latitudinally distributed array of ground-based GPS receivers in South America. Jicamarca Radio Observatory incoherent scatter radar measurements of vertical E\texttimesB drift are used in combination with the Low-Latitude IONospheric Sector (LLIONS) model to examine how penetration electric fields and meridional neutral winds shape low-latitude TEC. It is found that superfountain conditions pertain between \~1900 and 2100UT on 9 November, creating enhanced equatorial ionization anomaly (EIA) crests at \textpm20\textdegree geomagnetic latitude. Large-amplitude and/or long-duration changes in the electric field were found to produce significant changes in EIA plasma density and latitudinal location, with a delay time of \~2\textendash2.5h. Superfountain drifts were primarily responsible for EIA TEC levels; meridional winds were needed only to create hemispherical crest TEC asymmetries. The [O/N2] density ratio (derived from the GUVI instrument, flown on the TIMED satellite) and measurements of total atmospheric density (from the GRACE satellites), combined with TEC measurements, yield information regarding a likely CPZ that appeared on 10 November, suppressing TEC for over 16h.

Mannucci, Anthony; Tsurutani, Bruce; Kelley, Michael; Iijima, Byron; Komjathy, Attila;

Published by: Journal of Geophysical Research      Published on: Jan-01-2009

YEAR: 2009     DOI: 10.1029/2009JA014043

XUV Photometer System (XPS): Improved Solar Irradiance Algorithm Using CHIANTI Spectral Models

Woods, Thomas; Chamberlin, Phillip; Peterson, W.; Meier, R.; Richards, Phil; Strickland, Douglas; Lu, Gang; Qian, Liying; Solomon, Stanley; Iijima, B.; Mannucci, A.; Tsurutani, B.;

Published by: Solar Physics      Published on: Jan-08-2008

YEAR: 2008     DOI: 10.1007/s11207-008-9196-6

Correction of SOHO CELIAS/SEM EUV measurements saturated by extreme solar flare events

Didkovsky, LV; Judge, DL; Jones, AR; Wieman, S; Tsurutani, BT; McMullin, D;

Published by: Astronomische Nachrichten: Astronomical Notes      Published on:

YEAR: 2007     DOI:

Ionospheric behavior during the first few hours of intense geomagnetic storms

Mannucci, Anthony; Crowley, Geoff; Tsurutani, Bruce; Fuller-Rowell, Tim;

Published by:       Published on:

YEAR: 2006     DOI:

The October 28, 2003 extreme EUV solar flare and resultant extreme ionospheric effects: Comparison to other Halloween events and the Bastille Day event

Some of the most intense solar flares measured in 0.1 to 0.8 nm x-rays in recent history occurred near the end of 2003. The Nov 4 event is the largest in the NOAA records (X28) and the Oct 28 flare was the fourth most intense (X17). The Oct 29 flare was class X7. These flares are compared and contrasted to the July 14, 2000 Bastille Day (X10) event using the SOHO SEM 26.0 to 34.0 nm EUV and TIMED SEE 0.1\textendash194 nm data. High time resolution, \~30s ground-base GPS data and the GUVI FUV dayglow data are used to examine the flare-ionosphere relationship. In the 26.0 to 34.0 nm wavelength range, the Oct 28 flare is found to have a peak intensity greater than twice that of the Nov 4 flare, indicating strong spectral variability from flare-to-flare. Solar absorption of the EUV portion of the Nov 4 limb event is a possible cause. The dayside ionosphere responds dramatically (\~2.5 min 1/e rise time) to the x-ray and EUV input by an abrupt increase in total electron content (TEC). The Oct 28 TEC ionospheric peak enhancement at the subsolar point is \~25 TECU (25 \texttimes 10¹² electrons/cm²) or 30\% above background. In comparison, the Nov 4, Oct 29 and the Bastille Day events have \~5\textendash7 TECU peak enhancements above background. The Oct 28 TEC enhancement lasts \~3 hrs, far longer than the flare duration. This latter ionospheric feature is consistent with increased electron production in the middle altitude ionosphere, where recombination rates are low. It is the EUV portion of the flare spectrum that is responsible for photoionization of this region. Further modeling will be necessary to fully understand the detailed physics and chemistry of flare-ionosphere coupling.

Tsurutani, B.; Judge, D.; Guarnieri, F.; Gangopadhyay, P.; Jones, A.; Nuttall, J.; Zambon, G.A.; Didkovsky, L.; Mannucci, A.J.; Iijima, B.; Meier, R.; Immel, T.J.; Woods, T.; Prasad, S.; Floyd, L.; Huba, J.; Solomon, S.; Straus, P.; Viereck, R.;

Published by: Geophysical Research Letters      Published on: 02/2005

YEAR: 2005     DOI: 10.1029/2004GL021475

Violent Sun-Earth connection events of October-November 2003: Violent Sun-Earth connection events of October-November 2003

Tsurutani, BT; Judge, DL; Meier, RR; Immel, TJ; Woods, TN;

Published by: Geophysical research letters      Published on:

YEAR: 2005     DOI:

The extreme solar flares of October 28th and November 4th, 2003 and resultant extreme ionospheric effects

Tsurutani, B; Flare, Extreme; Team, Ionospheric;

Published by:       Published on:

YEAR: 2004     DOI: