Bibliography

Investigation of the negative ionospheric response of the 8 September 2017 geomagnetic storm over the European sector

In this study, we investigate the negative ionospheric response over the European sector during two storms that took place on 8 September 2017, primarily, by exploiting observations over ten European locations. The spatial and temporal variations of TEC, foF2 and hmF2 ionospheric characteristics are examined with the aim to explain the physical mechanisms underlying the strong negative ionospheric response. We detected very sharp electron density (in terms of foF2 and TEC) decrease during the main phases of the two storms and we attributed this phenomenon to the large displacement of the Midlatitude Ionospheric Trough (MIT). Our study also revealed that the two storms show different features caused by different processes. In addition, Large Scale Traveling Ionospheric Disturbances (LSTIDs) were observed during both storms, followed by enhanced Spread F conditions over Digisonde stations. The regional dependence of ionospheric storm effects was demonstrated, as the behavior of ionospheric effects over the northern part of Europe differed from that over the southern part.

Oikonomou, Christina; Haralambous, Haris; Paul, Ashik; Ray, Sarbany; Alfonsi, Lucilla; Cesaroni, Claudio; Sur, Dibyendu;

Published by: Advances in Space Research      Published on: aug

YEAR: 2022     DOI: 10.1016/j.asr.2022.05.035

Large-scale traveling ionospheric disturbances; Mid-latitude ionospheric trough; September 2017 geomagnetic storm; Swarm satellite

Climatological study of the ion temperature in the ionosphere as recorded by Millstone Hill incoherent scatter radar and comparison with the IRI model

Ion temperature data recorded by Millstone Hill incoherent scatter radar (42.61° N, 288.51° E) over four full solar cycles (from 1970 to 2018) are analyzed to depict its climatological behavior in the range of altitudes between 100 and 550 km. The ion temperature dependencies on altitude, local time, month of the year, and solar activity level are studied through a climatological analysis based on binning and boxplot representation of statistical values. Binned observations of ion temperature are compared with International Reference Ionosphere (IRI) modeled values (IRI-2016 version). This comparison reveals several shortcomings in the IRI modeling of the ion temperature at ionosphere altitudes, in particular for the altitudinal, diurnal, seasonal, and solar activity description. The main finding of this study is that the overall IRI overestimation of the ion temperature can be probably ascribed to the long-term ionosphere cooling. Moreover, the study suggests that the IRI ion temperature model needs to implement the seasonal and solar activity dependence, and introduce a more refined diurnal description to allow multiple diurnal maxima seen in observations. The IRI ion temperature anchor point at 430 km is investigated in more detail to show how also a better description of the altitude dependence is desirable for modeling purposes. Some hints and clues are finally given to improve the IRI ion temperature model.

Pignalberi, Alessio; Aksonova, Kateryna; Zhang, Shun-Rong; Truhlik, Vladimir; Gurram, Padma; Pavlou, Charalambos;

Published by: Advances in Space Research      Published on: sep

YEAR: 2021     DOI: 10.1016/j.asr.2020.10.025

Climatological analysis; International Reference Ionosphere model; ion temperature; Millstone Hill incoherent scatter radar

Field-Aligned Current During an Interval of BY-Dominated Interplanetary-Field; Modeled-to-Observed Comparisons

Carter, Jennifer; Samsonov, AA; Milan, Stephen; Branduardi-Raymont, Graziella; Ridley, Aaron; Paxton, Larry; Anderson, Brian; Waters, Colin; Edwards, Thomas;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2021     DOI:

Photoelectron transport and associated Far Ultraviolet emissions: Model simulation and comparison with observations

Liang, Jun; Sydorenko, Dmytro; Donovan, Eric; Rankin, Robert;

Published by:       Published on:

YEAR: 2021     DOI:

Field-aligned current during an interval of $$\backslash$rm B\_ $\$Y$\$ $-dominated interplanetary-field; modeled-to-observed comparisons

Carter, Jennifer; Samsonov, Andrey; Milan, Stephen; Branduardi-Raymont, Graziella; Ridley, Aaron; Paxton, Larry; Anderson, Brian; Waters, Colin; Edwards, Thomas;

Published by: Earth and Space Science Open Archive ESSOAr      Published on:

YEAR: 2021     DOI:

Thermospheric Composition and Solar EUV Flux From the Global-Scale Observations of the Limb and Disk (GOLD) Mission

Observations of far-ultraviolet (FUV) dayglow by the Global-scale Observations of Limb and Disk (GOLD) mission provide a new opportunity to monitor relative composition changes in the upper atmosphere as well as solar extreme ultraviolet (EUV) variability. Relative composition changes are quantified by ΣO/N2, the column density ratio of atomic oxygen to molecular nitrogen, while QEUV provides a measure of the solar EUV energy flux from 1 to 45 nm into the upper atmosphere. This spectral range provides the ionizing radiation which ultimately results in FUV airglow emission produced by photodissociation and photoelectron impact. The quantities ΣO/N2 and QEUV are derived from GOLD FUV observations through lookup tables that are constructed using a first-principles photoelectron transport model. The two FUV emissions used are O I 135.6 nm and the N2 Lyman-Birge-Hopfield (LBH) bands. We present an overview of the theoretical basis for the algorithms and practical considerations for application to GOLD data. The effects of uncertainties in electron impact cross sections, off-nadir viewing, and instrument artifacts are reviewed. We also discuss GOLD Level 1C DAY, Level 2 data products ON2 and QEUV, and present representative samples of each.

Correira, J.; Evans, J.; Lumpe, J.; Krywonos, A.; Daniell, R.; Veibell, V.; McClintock, W.; Eastes, R.;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2021     DOI: 10.1029/2021JA029517

GOLD; neutral composition; ON2; QEUV; radiative recombination; thermosphere

Estimating Precipitating Energy Flux, Average Energy, and Hall Auroral Conductance From THEMIS All-Sky-Imagers With Focus on Mesoscales

Recent attention has been given to mesoscale phenomena across geospace (∼10 s km to 500 km in the ionosphere or ∼0.5 RE to several RE in the magnetosphere), as their contributions to the system global response are important yet remain uncharacterized mostly due to limitations in data resolution and coverage as well as in computational power. As data and models improve, it becomes increasingly valuable to advance understanding of the role of mesoscale phenomena contributions—specifically, in magnetosphere-ionosphere coupling. This paper describes a new method that utilizes the 2D array of Time History of Events and Macroscale Interactions during Substorms (THEMIS) white-light all-sky-imagers (ASI), in conjunction with meridian scanning photometers, to estimate the auroral scale sizes of intense precipitating energy fluxes and the associated Hall conductances. As an example of the technique, we investigated the role of precipitated energy flux and average energy on mesoscales as contrasted to large-scales for two back-to-back substorms, finding that mesoscale aurora contributes up to ∼80\% (∼60\%) of the total energy flux immediately after onset during the early expansion phase of the first (second) substorm, and continues to contribute ∼30–55\% throughout the remainder of the substorm. The average energy estimated from the ASI mosaic field of view also peaked during the initial expansion phase. Using the measured energy flux and tables produced from the Boltzmann Three Constituent (B3C) auroral transport code (Strickland et al., 1976; 1993), we also estimated the 2D Hall conductance and compared it to Poker Flat Incoherent Scatter Radar conductance values, finding good agreement for both discrete and diffuse aurora.

Gabrielse, Christine; Nishimura, Toshi; Chen, Margaret; Hecht, James; Kaeppler, Stephen; Gillies, Megan; Reimer, Ashton; Lyons, Larry; Deng, Yue; Donovan, Eric; Evans, Scott;

Published by: Frontiers in Physics      Published on:

YEAR: 2021     DOI:

Diffuse and Pulsating Aurora

This chapter reviews fundamental properties and recent advances of diffuse and pulsating aurora. Diffuse and pulsating aurora often occurs on closed field lines and involves energetic electron precipitation by wave-particle interaction. After summarizing the definition, large-scale morphology, types of pulsation, and driving processes, we review observation techniques, occurrence, duration, altitude, evolution, small-scale structures, fast modulation, relation to high-energy precipitation, the role of ECH waves, reflected and secondary electrons, ionosphere dynamics, and simulation of wave-particle interaction. Finally we discuss open questions of diffuse and pulsating aurora.

Nishimura, Yukitoshi; Lessard, Marc; Katoh, Yuto; Miyoshi, Yoshizumi; Grono, Eric; Partamies, Noora; Sivadas, Nithin; Hosokawa, Keisuke; Fukizawa, Mizuki; Samara, Marilia; Michell, Robert; Kataoka, Ryuho; Sakanoi, Takeshi; Whiter, Daniel; Oyama, Shin-ichiro; Ogawa, Yasunobu; Kurita, Satoshi;

Published by: Space Science Reviews      Published on: 01/2020

YEAR: 2020     DOI: 10.1007/s11214-019-0629-3

Magnetospheric Conditions for STEVE and SAID: Particle Injection, Substorm Surge, and Field-Aligned Currents

Nishimura, Y; Yang, J; Weygand, JM; Wang, W; Kosar, B; Donovan, EF; , Angelopoulos; Paxton, LJ; Nishitani, N;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2020     DOI:

Neutral exospheric temperatures from the GOLD mission

Evans, JS; Lumpe, JD; Correira, J; , Veibell; Kyrwonos, A; McClintock, WE; Solomon, SC; Eastes, RW;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2020     DOI:

Magnetospheric conditions for STEVE and SAID: Particle injection, substorm surge, and field-aligned currents

Nishimura, Y; Yang, J; Weygand, JM; Wang, W; Kosar, B; Donovan, EF; , Angelopoulos; Paxton, LJ; Nishitani, N;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2020     DOI:

Small structural differences between two ferrocenyl diphenols determine large discrepancies of reactivity and biological effects

Tonolo, Federica; Salmain, Michèle; Scalcon, Valeria; Top, Siden; Pigeon, Pascal; Folda, Alessandra; Caron, Benoit; Mcglinchey, Michael; Toillon, Robert-Alain; Bindoli, Alberto; , others;

Published by: ChemMedChem      Published on:

YEAR: 2019     DOI:

Global-scale Observations of the Limb and Disk (GOLD): science implementation

McClintock, William; Eastes, Richard; Andersson, Laila; Burns, Alan; Codrescu, Mihail; Daniell, Robert; England, Scott; Evans, Scott; Krywonos, Andrey; Lumpe, Jerry; , others;

Published by:       Published on:

YEAR: 2018     DOI:

Driving of strong nightside reconnection and geomagnetic activity by polar cap flows: application to CME shocks and possibly other situations

Lyons, LR; Gallardo-Lacourt, B; Zou, Y; Nishimura, Y; Anderson, P; , Angelopoulos; Donovan, EF; Ruohoniemi, JM; Mitchell, E; Paxton, LJ; , others;

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

YEAR: 2018     DOI:

The Global-Scale Observations of the Limb and Disk (GOLD) Mission

The Earth\textquoterights thermosphere and ionosphere constitute a dynamic system that varies daily in response to energy inputs from above and from below. This system can exhibit a significant response within an hour to changes in those inputs, as plasma and fluid processes compete to control its temperature, composition, and structure. Within this system, short wavelength solar radiation and charged particles from the magnetosphere deposit energy, and waves propagating from the lower atmosphere dissipate. Understanding the global-scale response of the thermosphere-ionosphere (T-I) system to these drivers is essential to advancing our physical understanding of coupling between the space environment and the Earth\textquoterights atmosphere. Previous missions have successfully determined how the \textquotedblleftclimate\textquotedblright of the T-I system responds. The Global-scale Observations of the Limb and Disk (GOLD) mission will determine how the \textquotedblleftweather\textquotedblright of the T-I responds, taking the next step in understanding the coupling between the space environment and the Earth\textquoterights atmosphere. Operating in geostationary orbit, the GOLD imaging spectrograph will measure the Earth\textquoterights emissions from 132 to 162 nm. These measurements will be used image two critical variables\textemdashthermospheric temperature and composition, near 160 km\textemdashon the dayside disk at half-hour time scales. At night they will be used to image the evolution of the low latitude ionosphere in the same regions that were observed earlier during the day. Due to the geostationary orbit being used the mission observes the same hemisphere repeatedly, allowing the unambiguous separation of spatial and temporal variability over the Americas.

Eastes, R.; McClintock, W.; Burns, A.; Anderson, D.; Andersson, L.; Codrescu, M.; Correira, J.; Daniell, R.; England, S.; Evans, J.; Harvey, J.; Krywonos, A.; Lumpe, J.; Richmond, A.; Rusch, D.; Siegmund, O.; Solomon, S.; Strickland, D.; Woods, T.; Aksnes, A.; Budzien, S.; Dymond, K.; Eparvier, F.; Martinis, C.; Oberheide, J.;

Published by: Space Science Reviews      Published on: 10/2017

YEAR: 2017     DOI: 10.1007/s11214-017-0392-2

Scanless ultraviolet remote sensor for limb profile measurements from low earth orbit

Krywonos, Andrey; Harvey, James; Daniell, Robert; Eastes, Richard; Peterson, Gary;

Published by: Optical Engineering      Published on: Jan-10-2006

YEAR: 2016     DOI: 10.1117/1.2360200

Ionospheric effects of magnetospheric and thermospheric disturbances on March 17--19, 2015

Using vertical and oblique radio-sounding data, we analyze the ionospheric and thermospheric disturbances during the magnetic storm that occurred in northeastern Russia on March 17\textendash19, 2015. We consider the heliospheric sources that induced the magnetic storm. During the main and early recovery phases, the midlatitude stations are characterized by extremely low values of electron density at the F2 layer maximum. Using oblique sounding data, we recorded signals that propagated outside the great circle arc. In evening and night hours, no radio signals were found to pass along the Norilsk\textendashIrkutsk and Magadan\textendashIrkutsk paths. The observed ionospheric effects are shown to be caused by a sharp shift of the boundaries of the main ionospheric trough to the invariant latitude 46\textdegree N during the main phase of the magnetic storm. The negative ionospheric disturbance during the recovery phase of the storm, which was associated with significant variations in the composition of the neutral atmosphere, led to a change in the mode composition of received radio signals and a decline in observed maximal frequencies in daytime hours of March 18, 2015 by more than 2 times.

Polekh, N.; Zolotukhina, N.; Romanova, E.; Ponomarchuk, S.; Kurkin, V.; Podlesnyi, A.;

Published by: Geomagnetism and Aeronomy      Published on: 09/2016

YEAR: 2016     DOI: 10.1134/S0016793216040174

Ionospheric effects of magnetospheric and thermospheric disturbances on March 17—19, 2015

Using vertical and oblique radio-sounding data, we analyze the ionospheric and thermospheric disturbances during the magnetic storm that occurred in northeastern Russia on March

Polekh, NM; Zolotukhina, NA; Romanova, EB; Ponomarchuk, SN; Kurkin, VI; Podlesnyi, AV;

Published by: Geomagnetism and Aeronomy      Published on:

YEAR: 2016     DOI:

Characteristics of post-midnight L-band scintillation in the transition region from the equatorial to mid-latitudes over the Indian longitude sector using COSMIC, C/NOFS and GPS measurements

Occurrence of L band scintillations around midnight and postmidnight hours have not been well studied and reported from the higher equatorial latitudes in the transition region from the equatorial to midlatitudes over the Indian longitude sector. The present paper reports cases of postmidnight L band scintillation observations by COSMIC during March 2014 over the Indian longitude sector. GPS\ S₄measurements from the International Global Navigation Satellite Systems Service station at Lucknow (26.91\textdegreeN, 80.96\textdegreeE geographic; magnetic dip: 39.75\textdegreeN) corroborate occurrence of postmidnight scintillations. The\ F\ region vertical upward velocities around the magnetic equator during evening hours have been used to understand the possibility of impact of irregularities generated over the magnetic equator at latitudes north of 30\textdegreeN. Postmidnight L band scintillations at latitudes greater than 30\textdegreeN without corresponding premidnight scintillations present interesting scientific scenario and give rise to suggestions of (1) any coupling mechanism between the equatorial and midlatitudes through which irregularities seeded in the midlatitudes may affect transionospheric satellite links at low latitudes or (2) irregularity generation at midlatitudes not connected with equatorial instabilities. Long-term analysis of\ S₄\ at L band measured by COSMIC over the Indian longitudes during March 2007\textendash2014 exhibits a well-defined longitude swath around 75\textendash83\textdegreeE of reduced (0.2 \< S₄ \< 0.4) or no scintillations which may be attributed to the longitudinal variability of scintillation occurrence following the global four-cell pattern of ionospheric activity.

Paul, A.; Haralambous, H.; Oikonomou, C.;

Published by: Radio Science      Published on: 12/2015

YEAR: 2015     DOI: 10.1002/2015RS005807

postmidnight L band scintillation over Indian longitude sector

Link between pre-midnight second harmonic poloidal waves and auroral undulations: Conjugate observations with a Van Allen Probes spacecraft and a THEMIS all-sky imager

We report, for the first time, an auroral undulation event on 1 May 2013 observed by an all-sky imager (ASI) at Athabasca (L = 4.6), Canada, for which in situ field and particle measurements in the conjugate magnetosphere were available from a Van Allen Probes spacecraft. The ASI observed a train of auroral undulation structures emerging spontaneously in the pre-midnight subauroral ionosphere, during the growth phase of a substorm. The undulations had an azimuthal wavelength of ~180 km and propagated westward at a speed of 3\textendash4 km s^-1. The successive passage over an observing point yielded quasi-periodic oscillations in diffuse auroral emissions with a period of ~40 s. The azimuthal wave number m of the auroral luminosity oscillations was found to be m ~ -103. During the event the spacecraft \textendash being on tailward stretched field lines ~0.5 R_E outside the plasmapause that mapped into the ionosphere conjugate to the auroral undulations \textendash encountered intense poloidal ULF oscillations in the magnetic and electric fields. We identify the field oscillations to be the second harmonic mode along the magnetic field line through comparisons of the observed wave properties with theoretical predictions. The field oscillations were accompanied by oscillations in proton and electron fluxes. Most interestingly, both field and particle oscillations at the spacecraft had one-to-one association with the auroral luminosity oscillations around its footprint. Our findings strongly suggest that this auroral undulation event is closely linked to the generation of second harmonic poloidal waves

Motoba, T.; Takahashi, K.; Ukhorskiy, A.; Gkioulidou, M.; Mitchell, D.; Lanzerotti, L.; Korotova, G.; Donovan, E.; Wygant, J.; Kletzing, C.; Kurth, W.; Blake, J.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 02/2015

YEAR: 2015     DOI: 10.1002/2014JA020863

Characteristics of postmidnight L band scintillation in the transition region from the equatorial to midlatitudes over the Indian longitude sector using COSMIC, C/NOFS, and GPS measurements

Paul, A; Haralambous, H; Oikonomou, C;

Published by: Radio Science      Published on:

YEAR: 2015     DOI:

The GOLD Science Data Center-Algorithm Heritage, Data Product Descriptions and User Services

Lumpe, JD; Foroosh, H; Eastes, R; Krywonos, A; Evans, JS; Burns, AG; Strickland, DJ; Daniell, RE; England, S; Solomon, SC; , others;

Published by:       Published on:

YEAR: 2013     DOI:

The Science of the Global-scale measurements of the Limb and Disk (GOLD) Mission

Burns, AG; Eastes, R; McClintock, WE; Solomon, SC; Anderson, DN; Andersson, L; Codrescu, M; Daniell, RE; Harvey, J; Krywonos, A; , others;

Published by:       Published on:

YEAR: 2013     DOI:

Remote sensing of neutral temperatures in the Earth\textquoterights thermosphere using the Lyman-Birge-Hopfield bands of N ₂ : Comparisons with satellite drag data

This paper presents remotely sensed neutral temperatures obtained from ultraviolet observations and compares them with temperatures from the NRLMSISE-00 version of the Mass Spectrometer and Incoherent Scatter (MSIS) model (unconstrained and constrained to match the total densities from satellite drag). Latitudinal profiles of the temperatures in the Earth\textquoterights thermosphere are obtained by inversion of high-resolution (\~1.3\ \r A) observations of the (1,1) and (5,4) Lyman-Birge-Hopfield (LBH) bands of N₂. The spectra are from the High resolution Ionospheric and Thermospheric Spectrograph (HITS) instrument aboard the Advanced Research and Global Observation Satellite (ARGOS). The results indicate that on each day examined there was consistency between the remotely sensed thermospheric temperatures, the densities from coincident satellite drag measurements at adjacent altitudes, and the NRLMSISE-00 model.

Krywonos, Andrey; Murray, D.; Eastes, R.; Aksnes, A.; Budzien, S.; Daniell, R.;

Published by: Journal of Geophysical Research      Published on: 09/2012

YEAR: 2012     DOI: 10.1029/2011JA017226

airglow; N2; remote sensing; satellite drag; temperature; thermosphere

Modeled and observed N ₂ Lyman-Birge-Hopfield band emissions: A comparison

Eastes, R.; Murray, D.; Aksnes, A.; Budzien, S.; Daniell, R.; Krywonos, A.;

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

YEAR: 2011     DOI: 10.1029/2010JA016417

Modeled and observed N2 Lyman-Birge-Hopfield band emissions: A comparison

Eastes, RW; Murray, DJ; Aksnes, A; Budzien, SA; Daniell, RE; Krywonos, A;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2011     DOI:

Geomagnetic and Ionospheric Response to Recurrent Geomagnetic Activity at Middle Latitudes

[8] have also reported 9-day periodic oscillations in the ΣO/N2 ratio measured by the Global Ultraviolet Imager (GUVI) on the TIMED satellite. The thermosphere neutral density

Mukhtarov, Plamen; Pancheva, Dora; Trifonova, Petya;

Published by: Comptes rendus de l’Acad\ emie bulgare des Sciences      Published on:

YEAR: 2011     DOI:

Direct measurements of the Poynting flux associated with convection electric fields in the magnetosphere

Nishimura, Y.; Kikuchi, T.; Shinbori, A.; Wygant, J.; Tsuji, Y.; Hori, T.; Ono, T.; Fujita, S.; Tanaka, T.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2010

YEAR: 2010     DOI: 10.1029/2010JA015491

Program of transient UV event research at Tatiana-2 satellite

Garipov, G.; Khrenov, B.; Klimov, P.; Morozenko, V.; Panasyuk, M.; Petrova, S.; Tulupov, V.; Shahparonov, V.; Svertilov, S.; Vedenkin, N.; Yashin, I.; Jeon, J.; Jeong, S.; Jung, A.; Kim, J.; Lee, J.; Lee, H; Na, G.; Nam, J.; Nam, S.; Park, I.; Suh, J.; Jin, J; Kim, M.; Kim, Y.; Yoo, B.; Park, Y.-S.; Yu, H.; Lee, C.-H.; Park, J.; Salazar, H.; Martinez, O.; Ponce, E.; Cotsomi, J.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2010

YEAR: 2010     DOI: 10.1029/2009JA014765

Ionospheric E-Region Chemistry and Energetics

Mertens, Christopher; Mlynczak, Martin; Gronoff, Guillaume; Yee, Jeng-Hwa; Swenson, Charles; Fish, Chad; Wellard, Stan; Lumpe, Jerry; Strickland, Doug; Evans, Scott;

Published by: To propose an Earth-observing, multi-satellite science mission to explore the last remaining frontier in upper atmospheric research—the ionospheric E-region      Published on:

YEAR: 2010     DOI:

Satellite and ground-based observations of auroral energy deposition and the effects on thermospheric composition during large geomagnetic storms: 1. Great geomagnetic storm of 20 November 2003

Hecht, JH; Mulligan, T; Strickland, DJ; Kochenash, AJ; Murayama, Y; Tanaka, Y-M; Evans, DS; Conde, MG; Donovan, EF; Rich, FJ; , others;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2008     DOI:

Oscillations of the equatorward boundary of the ion auroral oval – radar observations

Three SuperDARN radars in the afternoon-midnight sector of the auroral oval detected a boundary oscillation, originating near ∼1800 MLT sector. Analysis of the phase of the oscillations measured in three meridians indicates that the disturbance has a longitudinally (azimuthally) isolated source and away from which it propagates. The eastward and westward phase speeds are 2.6 and 3.6 km/s respectively and the period is roughly 28 minutes. An examination of the geo-synchronous magnetic field inclination also revealed oscillations similar to the oscillations of the boundary. Solar wind and IMF conditions were steady during the period except for variations of the IMF By component. The IMF By component showed variations similar to the oscillations in the boundary and the geo-synchronous magnetic field inclination. During reduced and negative IMF By, the boundary was moving equatorward, while during increased or positive IMF By it was moving poleward. The variations in the magnetic field inclination measured at geosynchronous orbit by the GOES satellites were consistent with these boundary motions: decreases (more stretched) and increases (more dipolar) in the inclination corresponded to equatorward and poleward moving boundaries, respectively. Polar cap convection also showed changes in the direction of the convection in response to the change in the IMF By component. Observed oscillation of the boundary can be explained by stretching of the tail field lines due to asymmetric merging associated with changes in the By component of the interplanetary magnetic field.

Jayachandran, P.; Sato, N.; Ebihara, Y.; Yukimatu, A.; Kadokura, A.; MacDougall, J.; Donovan, E.; Liou, K.;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2008     DOI: https://doi.org/10.1029/2007JA012870

Boundary oscillation; SuperDARN radars; Convection