GUVI Biblio


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Found 665 entries in the Bibliography.

Showing entries from 1 through 50


Corotation of ring current auroral spots at sub-auroral latitudes

We report observations of auroral spots s at sub-auroral latitudes. The auroral spots occurred during storm-recovery phases and corotated with the Earth at a speed either higher (super-rotation) or lower (sub-rotation) than the Earth\textquoterights rotation rate. In the dawn side, the spots have a slightly higher probability of super-rotation than that of the duskside auroral spots. The super- and sub-rotation is likely due to dynamics of the plasmasphere that is controlled by both drag (sub-rotation) and solar wind driv ...

Zhang, Yongliang; Paxton, Larry;

YEAR: 2020     DOI: 10.1016/j.jastp.2020.105195

Auroral spots; Corotation; Sub-auroral latitude

Improving Neutral Density Predictions Using Exospheric Temperatures Calculated on a Geodesic, Polyhedral Grid

A new model of exospheric temperatures has been developed, with the objective of predicting global values with greater spatial and temporal accuracy. From these temperatures, the neutral densities in the thermosphere can be calculated, through use of the Naval Research Laboratory Mass Spectrometer and Incoherent Scatter radar Extended (NRLMSISE-00) model. The exospheric temperature model is derived from measurements of the neutral densities on several satellites. These data were sorted into triangular c ...

Weimer, D.; Mehta, P.; Tobiska, W.; Doornbos, E.; Mlynczak, M.; Drob, D.; Emmert, J.;

YEAR: 2020     DOI: 10.1029/2019SW002355

Multi-scale ionosphere responses to the May 2017 magnetic storm over the Asian sector

We investigate multi-scale ionospheric responses to the May 27, 2017, geomagnetic storm over the Asian sector by using multi-instrumental observations, including ground-based global navigation satellite systems (GNSS) network, constellation observing system for meteorology, ionosphere and climate radio occultation, the FengYun-3C (FY-3C) GNSS occultation sounder electron density profiles and in situ plasma density observations provided by both Swarm and defense meteorological satellite program missions. This geomagnetic s ...

Liu, Lei; Zou, Shasha; Yao, Yibin; Aa, Ercha;

YEAR: 2020     DOI: 10.1007/s10291-019-0940-1

Blob structure; Positive and negative ionosphere responses; TID; Geomagnetic storms

Effect of moderate geomagnetic storms on equatorial plasma bubbles over eastern Africa in the year 2012: Evolution and electrodynamics

Equatorial plasma bubbles (EPBs) are common features of the equatorial and low-latitude ionosphere and are known to cause radio wave scintillation which leads to the degradation of communication and navigation systems. Although these structures have been studied for decades, a full understanding of their evolution and dynamics remains important for space weather mitigation purposes. In this study, we present cases of EPBs occurrences around April and July 2012 geomagnetic storm periods over the African ...

Giday, Nigussie; Katamzi-Joseph, Zama; Stoneback, Russell;

YEAR: 2020     DOI: 10.1016/j.asr.2020.01.013

C/NOFS; Equatorial electrojets; equatorial plasma bubbles

A method to derive global O/N2 ratios from SSUSI/DMSP based on Re-AURIC algorithm

Global thermospheric O/N2 column density ratios are obtained using the SSUSI/DMSP far-ultraviolet (FUV) dayglow data and the Re-AURIC simulation results. The Re-AURIC is derived from the AURIC algorithm after some old modules are updated. The calculation processes of O/N2 ratio are then established using the simulations of Re-AURIC to calibrate the ratios of the OI 135.6\ nm emission and N2 LBHS emission from SSUSI observations. The standard deviation (1σ) and correlation co ...

Ding, GuangXing; Chen, Bo; Zhang, Xiaoxin; He, Fei;

YEAR: 2020     DOI: 10.1016/j.jastp.2020.105196

FUV dayglow; Magnetic storm; O/N2 ratio; Re-AURIC

Multi-wavelength coordinated observations of ionospheric irregularity structures from an anomaly crest location during unusual solar minimum of the 24th cycle

The present paper reports coordinated ionospheric irregularity measurements at optical as well as GPS wavelengths. Optical measurements were obtained from Tiny Ionospheric Photometer (TIP) sensors installed onboard the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. GPS radio signals were obtained from a dual frequency GPS receiver operational at Calcutta (22.58\textdegreeN, 88.38\textdegreeE geographic; geomagnetic dip: 32.96\textdegree; 13.00\textdegreeN, 161.63\textdegreeE g ...

Paul, Ashik; Sur, Dibyendu; Haralambous, Haris;

YEAR: 2020     DOI: 10.1016/j.asr.2019.11.035

GPS radio measurements; ionospheric irregularities; Northern crest of EIA; Optical measurements; solar minimum; TIP

Response of the low- to mid-latitude ionosphere to the geomagnetic storm of September 2017

We study the impact of the geomagnetic storm of 7\textendash9\ September\ 2017 on the low- to mid-latitude ionosphere. The prominent feature of this solar event is the sequential occurrence of two SYM-H minima with values of -146 and -115 nT on 8\ September at 01:08 and 13:56 UT, respectively. The study is based on the analysis of data from the Global Positioning System (GPS) stations and magnetic observatories located at different longitudinal sectors corresponding to the Pacific, Asia, Africa and the Amer ...

Imtiaz, Nadia; Younas, Waqar; Khan, Majid;

YEAR: 2020     DOI: 10.5194/angeo-38-359-2020

Temporal evolution of substorm-driven global Alfv\ en wave power above the auroral acceleration region

The onset of substorms is associated with bursty enhancements of Alfv\ en wave power throughout the magnetotail. While impossible to assess the total Alfv\ en wave power in the entire magnetotail, we have instead monitored waves that are funneled into the auroral acceleration region, in order to assess the temporal evolution of Alfv\ en wave power above the nightside auroral zone in relation to substorm phases. The substorms were grouped by three conditions: nonstorm periods, storm periods, and all (unc ...

Keiling, Andreas; Thaller, Scott; Dombeck, John; Wygant, John;

YEAR: 2020     DOI: 10.1029/2019JA027444

Alfven wave; Alfvenic electron; AURORA; auroral acceleration; magnetotail; Substorm

Aurora in the Polar Cap: A Review

This paper reviews our current understanding of auroral features that appear poleward of the main auroral oval within the polar cap, especially those that are known as Sun-aligned arcs, transpolar arcs, or theta auroras. They tend to appear predominantly during periods of quiet geomagnetic activity or northwards directed interplanetary magnetic field (IMF). We also introduce polar rain aurora which has been considered as a phenomenon on open field lines. We describe the morphology of such auroras, their ...

Hosokawa, Keisuke; Kullen, Anita; Milan, Steve; Reidy, Jade; Zou, Ying; Frey, Harald; Maggiolo, Romain; Fear, Robert;

YEAR: 2020     DOI: 10.1007/s11214-020-0637-3

Auroral Structure and Dynamics From GOLD

The Global-scale Observations of the Limb and Disk (GOLD) mission data contain significant quantitative information about the aurora on a global scale. Here we present techniques for quantifying such information, including the temporal development of the structure within the auroral oval using the GOLD images. These techniques are applied to auroral observations in the GOLD data, in particular showing an example of how the longitudinal structure within the aurora varies over the course of six consecutive days with differi ...

Michell, R.;

YEAR: 2020     DOI: 10.1029/2019JA027650


Dynamical Properties of Peak and Time-Integrated Geomagnetic Events Inferred From Sample Entropy

We provide a comprehensive statistical analysis of the sample entropy of peak and time-integrated geomagnetic events in 2001\textendash2017, considering different measures of event strength, different geomagnetic indices, and a simplified solar wind-magnetosphere coupling function urn:x-wiley:jgra:media:jgra55526:jgra55526-math-0001. Our investigations ...

Mourenas, D.; Artemyev, A.; Zhang, X.-J.;

YEAR: 2020     DOI: 10.1029/2019JA027599

Dynamical complexity; Entropy; geomagnetic indices; Geomagnetic storms; Solar wind magnetosphere coupling

Evaluation on the Quasi-Realistic Ionospheric Prediction Using an Ensemble Kalman Filter Data Assimilation Algorithm

In this work, we evaluated the quasi-realistic ionosphere forecasting capability by an ensemble Kalman filter (EnKF) ionosphere and thermosphere data assimilation algorithm. The National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model is used as the background model in the system. The slant total electron contents (TECs) from global International Global Navigation Satellite Systems Service ground-based receivers and from the Constellation Observing System for Meteorology, ...

He, Jianhui; Yue, Xinan; Le, Huijun; Ren, Zhipeng; Wan, Weixing;

YEAR: 2020     DOI: 10.1029/2019SW002410

Investigating Magnetosphere-Ionosphere-Thermosphere (M-I-T) Coupling Occurring During the 7\textendash8 November 2004 Superstorm

In this study, we investigate the shock-sheath driven 7\textendash8 November 2004 superstorm for its flux transfer events and resultant flow channel (FC) events and associated neutral (DN) and electron (Ne) density features in order to understand better the underlying coupled magnetosphere (M) and ionosphere (I) processes and responses in the thermosphere (T). We focus on the (i) subauroral, auroral, and polar cap regions, (ii) localized DN increases and associated Ne features and ...

Horvath, Ildiko; Lovell, Brian;

YEAR: 2020     DOI: 10.1029/2019JA027484

flow channels; large-scale FACs; localized neutral density increases; nitric oxide (NO); Poynting flux; type-1 and type-2 aurorae

Modeled IMF B y Effects on the Polar Ionosphere and Thermosphere Coupling

There is still an inadequate understanding of how the interplanetary magnetic field (IMF) east-west component (By) affects thermospheric composition, and other ionospheric and thermospheric fields in a systematic way. Utilizing the state-of-art first-principles Coupled Magnetosphere Ionosphere Thermosphere (CMIT) modeling and TIMED/Global Ultraviolet Imager (GUVI)-observed ΣO/N2 covering an entire solar cycle (year 2002\textendash2016), as well as a neutral parcel trajectory tracin ...

Liu, Jing; Burns, Alan; Wang, Wenbin; Zhang, Yongliang;

YEAR: 2020     DOI: 10.1029/2019JA026949

Modeling the Impact of Metallic Ion Layers on Equatorial Spread With SAMI3/ESF

The impact of urn:x-wiley:grl:media:grl60258:grl60258-math-0005 region metal ion layers on the development of equatorial plasma bubbles is investigated using the SAMI3/ESF model. We find that metal ion layers reduce the growth rate of the generalized Rayleigh-Taylor instability (GRTI) and act to suppress the development of equatorial plasma bubbles. This is consistent with ...

Huba, J.; Krall, J.; Drob, D.;

YEAR: 2020     DOI: 10.1029/2020GL087224

Equatorial ionosphere; Equatorial Spread F; metal ions; sporadic E

Traits of sub-kilometre F-region irregularities as seen with the Swarm satellites

During the night, in the F-region, equatorial ionospheric irregularities manifest as plasma depletions observed by satellites, and they may cause radio signals to fluctuate. In this study, the distribution characteristics of ionospheric F-region irregularities in the low latitudes were investigated using 16 Hz electron density observations made by a faceplate which is a component of the electric field instrument (EFI) onboard Swarm satellites of the European Space Agency (ESA). The study covers the peri ...

Aol, Sharon; Buchert, Stephan; Jurua, Edward;

YEAR: 2020     DOI: 10.5194/angeo-38-243-2020

A case study of isolated auroral spots based on DMSP data

This study employed ultraviolet images and particle data to investigate isolated auroral spots away from the Earth\textquoterights auroral oval. Data from SSUSI (Special Sensor Ultraviolet Spectrographic Imager) and SSJ (Special Sensor J) mounted on the DMSP (Defence Meteorological Satellite Program) spacecraft were examined. The isolated auroral spots were observed by DMSP F16/SSUSI and F17/SSUSI on 29 May 2010 during the recovery phase of a moderate geomagnetic storm with a minimum SYM-H index of -70 ...

Zhou, Su; Chen, Yuqing; Zhang, Jin;

YEAR: 2020     DOI: 10.1016/j.jastp.2019.105176

Isolated auroral spots; Proton aurora; Subauroral electron precipitation

Comparison of Reference Heights of O/N 2 and ∑O/N 2 Based on GUVI Dayside Limb Measurement

We define a new thermospheric concept, the reference heights of O/N2, referring to a series of thermospheric heights corresponding to the fixed ratios of O to N2 number density. Here, based on Global Ultraviolet Imager (GUVI) limb measurement, we compare O/N2 column density ratio (∑O/N2) and the reference heights of O/N2. We choose the transition height of O and N2 (transition height hereafter), a special reference height at which O number density is equa ...

Yu, Tingting; Ren, Zhipeng; Yu, You; Yue, Xinan; Zhou, Xu; Wan, Weixing;

YEAR: 2020     DOI: 10.1029/2019SW002391

O/N2 ratio

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 E ...

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;

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

The Far Ultraviolet Signatures of Conjugate Photoelectrons Seen by the Special Sensor Ultraviolet Spectrographic Imager

This study investigates the origin of anomalous far ultraviolet emissions observed at night at the subauroral region by the Special Sensor Ultraviolet Spectrographic Imager on board the Defense Meteorological Satellite System-F16 satellite. The global distribution of the anomalous emission is derived using the measurements of the oxygen atom 130.4-nm emission in 2017. Our results show the extension of the anomalous emission from high latitudes to middle latitudes in the Northern American-Atlantic sector during the Decembe ...

Kil, Hyosub; Schaefer, Robert; Paxton, Larry; Jee, Geonhwa;

YEAR: 2020     DOI: 10.1029/2019GL086383

conjugate photoelectron; far ultraviolet emission; thermosphere; remote sensing data

Impacts of Binning Methods on High-Latitude Electrodynamic Forcing: Static Versus Boundary-Oriented Binning Methods

An outstanding issue in the general circulation model simulations for Earth\textquoterights upper atmosphere is the inaccurate estimation of Joule heating, which could be associated with the inaccuracy of empirical models for high-latitude electrodynamic forcing. The binning methods used to develop those empirical models may contribute to the inaccuracy. Traditionally, data are binned through a static binning approach by using fixed geomagnetic coordinates, in which the dynamic nature of the forcing is ...

Zhu, Qingyu; Deng, Yue; Richmond, Arthur; Maute, Astrid; Chen, Yun-Ju; Hairston, Marc; Kilcommons, Liam; Knipp, Delores; Redmon, Robert; Mitchell, Elizabeth;

YEAR: 2020     DOI: 10.1029/2019JA027270

Electric field; high latitude; Joule heating; particle precipitation

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 t ...

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

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

Real-Time Thermospheric Density Estimation via Two-Line Element Data Assimilation

Inaccurate estimates of the thermospheric density are a major source of error in low Earth orbit prediction. Therefore, real-time density estimation is required to improve orbit prediction. In this work, we develop a dynamic reduced-order model for the thermospheric density that enables real-time density estimation using two-line element (TLE) data. For this, the global thermospheric density is represented by the main spatial modes of the atmosphere and a time-varying low-dimensional state and a linear ...

Gondelach, David; Linares, Richard;

YEAR: 2020     DOI: 10.1029/2019SW002356

density estimation; reduced-order modeling; satellite drag; thermospheric density modeling; two-line element data

The Dynamical IonosphereStorms and substorms\textemdashThe new whole system approach and future challenges

This chapter covers our current understanding and recent advances in the study of Earth\textquoterights ionosphere during magnetic storms and substorms with a special focus on electrodynamics and its consequences in the past 14 years. In particular, the focus is on the new awareness of looking at the magnetosphere, ionosphere, and thermosphere (M-I-T) as a whole system that has brought us to the next level of understanding. Both ground-based observations and the new space-based observations from magneto ...

Maruyama, Naomi;

YEAR: 2020     DOI: 10.1016/B978-0-12-814782-5.00009-1


Dayside Aurora

Dayside aurora is related to processes in the dayside magnetosphere and especially at the dayside magnetopause. A number of dayside aurora phenomena are driven by reconnection between the solar wind interplanetary magnetic field and the Earth\textquoterights internal magnetic field at the magnetopause. We summarize the properties and origin of aurora at the cusp foot point, High Latitude Dayside Aurora (HiLDA), Poleward Moving Auroral Forms (PMAFs), aurora related to traveling convection vortices (TCV), and throat aurora. ...

Frey, Harald; Han, Desheng; Kataoka, Ryuho; Lessard, Marc; Milan, Stephen; Nishimura, Yukitoshi; Strangeway, Robert; Zou, Ying;

YEAR: 2019     DOI: 10.1007/s11214-019-0617-7

The dependence of four-peak longitudinal structure of the tropical electric field on the processes in the lower atmosphere and geomagnetic field configuration

Klimenko, V.V.; Klimenko, M.V.; Bessarab, F.S.; Sukhodolov, T.V.; Rozanov, E.V.;

YEAR: 2019     DOI: 10.1016/j.asr.2019.06.029

Effects of the interplanetary magnetic field y component on the dayside aurora

A dawn\textendashdusk asymmetry in many high-latitude ionospheric and magnetospheric phenomena, including the aurora, can be linked to the east\textendashwest (y) component of the interplanetary magnetic field (IMF). Owing to the scarcity of observations in the Southern Hemisphere, most of the previous findings are associated with the Northern Hemisphere. It has long been suspected that if the IMF By component also produces a dawn\textendashdusk asymmetry and/or a mirror image in the ...

Liou, K.; Mitchell, E.;

YEAR: 2019     DOI: 10.1186/s40562-019-0141-3

Radiative cooling due to NO at 5.3

The effect of geomagnetic storms on the peak emission of NO Volume Emission Rate (NO VER) at 5.3 m, in mesosphere and lower thermosphere (MLT) region, is studied over the Asian sector during 26\textendash29 September 2011 (storm 1) and 18\textendash21 February 2014 (storm 2). The data for peak emission of NO VER is obtained from SABER instrument onboard the NASA\textquoterights TIMED satellite. The SABER retrieved data along with the neutral densities obtained from NRLMSISE-00 model have been used to study the latitudinal ...

Bharti, Gaurav; Krishna, M.V.; Singh, Vir;

YEAR: 2019     DOI: 10.1016/j.asr.2019.07.016

Characteristics of GNSS total electron content enhancements over the mid-latitudes during a geomagnetic storm on November 7 and 8, 2004

The characteristics of global electron density variations in the ionosphere during a geomagnetic storm on November 7 and 8, 2004, were investigated using total electron content (TEC) obtained from the global navigation satellite system (GNSS). The regions of enhanced TEC over North America, Europe, and Japan first appeared in the mid-latitude regions. The TEC enhancements over North America showed a rapid longitudinal expansion and reached a wide longitudinal extent during the initial and main phases of the geomagnetic st ...

Sori, T.; Shinbori, A.; Otsuka, Y.; Tsugawa, T.; Nishioka, M.;

YEAR: 2019     DOI: 10.1029/2019JA026713

Conjugate hemispheric response of earth\textquoterights ionosphere due to geomagnetic storms occurred during two equinox periods

The ionospheric response of two geomagnetic storms of 2016 occurred during spring equinox (5-8 March, 2016) and autumn equinox (12-15 October, 2016) is investigated using the total electron content (TEC) data derived from Global Positioning System (GPS) receivers located in the equatorial ionization anomaly (EIA) crest regions at northern hemisphere (Tripura University, Agartala, India) and southern hemisphere (Karratha, Australia). While in southern EIA station ionospheric responses for the two storms are found to be sym ...

Patari, Arup; De, Barin; Guha, Anirban; Paul, Bapan;

YEAR: 2019     DOI: 10.1088/1742-6596/1330/1/012004

Effects of CME and CIR induced geomagnetic storms on low-latitude ionization over Indian longitudes in terms of neutral dynamics

This paper presents the response of the ionosphere during the intense geomagnetic storms of October 12\textendash20, 2016 and May 26\textendash31, 2017 which occurred during the declining phase of the solar cycle 24. Total Electron Content (TEC) from GPS measured at Indore, Calcutta and Siliguri having geomagnetic dips varying from 32.23\textdegreeN, 32\textdegreeN and 39.49\textdegreeN respectively and at the International GNSS Service (IGS) stations at Lucknow (beyond anomaly crest), Hyderabad (between geomagnetic equat ...

Chakraborty, S.; Ray, S.; Sur, D.; Datta, A.; Paul, A.;

YEAR: 2019     DOI: 10.1016/j.asr.2019.09.047

Isolated Auroral Spots Observed by DMSP/SSUSI

This work reports auroral spots event observed by the SSUSI instruments on board the DMSP spacecraft between 22 and 23 July 2009 during the recovery phase of a moderate magnetic storm. The spots were observed between 18:00 and 02:00 magnetic local time and stayed at ~60\textdegree magnetic latitude. They lasted for ~10 hr and corotated with ~64\% of the Earth\textquoterights rotational speed. In situ observations indicate that the isolated auroral spots were produced by energetic ions at energies between 10 and 240 keV, w ...

Zhou, Su; Luan, Xiaoli; Pierrard, Viviane; Han, Desheng;

YEAR: 2019     DOI: 10.1029/2019JA026853

Morphological study on the ionospheric variability at Bharati, a polar cusp station in the southern hemisphere

Morphological features of the quiet/disturbed time variations in the Total Electron Content (TEC) at the polar cusp station Bharati (76.69\textdegreeS MLAT) during a period of 5 years starting from February 2013 to December 2017 has been studied using GPS TEC measurements. The TEC at Bharati follows a diurnal pattern with its peak appearing close to local noon/magnetic noon during the summer/winter months. A nighttime enhancement in the TEC is seen around the magnetic midnight during winter. The plasma density at Bharati ...

Shreedevi, P.R.; Choudhary, R.K.; Yu, Yiqun; Thomas, Evan;

YEAR: 2019     DOI: 10.1016/j.jastp.2019.105058

A new method for deriving the nightside thermospheric density based on GUVI dayside limb observations

We propose a new method to derive the nightside thermsopheric density by extending GUVI dayside limb observations using empirical orthogonal function (EOF) analysis. First, we acquire the GUVI dayside total mass density during 2002-2005 to construct a preliminary empirical model (EM). Simultaneously, we decompose the background thermospheric density from US Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar Extended (NRLMSISE-00) model into different empirical orthogonal functions (EOFs). The decompo ...

Yu, Tingting; Ren, Zhipeng; Yu, You; Wan, Weixing;

YEAR: 2019     DOI: 10.1029/2019SW002304

Quantification of the vertical transport and escape of atomic hydrogen in the terrestrial upper atmosphere

Measurements of the limiting escape rate of atomic hydrogen (H) atoms at Earth, and the relative significance of thermal evaporation and non-thermal escape mechanisms, such as charge exchange and polar wind, have long been lacking. Our recent development of sophisticated radiative transport analysis techniques now enables the reliable interpretation of remotely-sensed measurements of optically-thick H emission, such as those acquired along the Earth\textquoterights limb by the Global Ultraviolet Imager (GUVI) onboard the ...

Joshi, P.P.; Phal, Y.D.; Waldrop, L.S.;

YEAR: 2019     DOI: 10.1029/2019JA027057

Response of the Earth\textquoterights equatorial ionosphere during the severe G4-class geomagnetic storm of 8 th September 2017

Equatorial and low latitude ionospheric response of the 8th September 2017 severe G4-class geomagnetic storm is investigated using the total electron content (TEC) data from a longitudinal chain of global positioning system (GPS) receivers over Asian, African and American sectors. During the main phase, a positive storm effect is observed over Asian sector, a complete negative storm effect over African sector and both are observed over American sector. A sharp increase in peak TEC is observed over the complete ...

Paul, Bapan; Patari, Arup; De, Barin; Guha, Anirban;

YEAR: 2019     DOI: 10.1088/1742-6596/1330/1/012005

Understanding the global dynamics of the equatorial ionosphere in Africa for space weather capabilities: A science case for AfrequaMARN

Upper Atmosphere Radiance Data Assimilation: A Feasibility Study for GOLD Far Ultraviolet Observations

Far ultraviolet observations of Earth\textquoterights dayglow from the National Aeronautics and Space Administration (NASA) Global-scale Observations of the Limb and Disk (GOLD) mission presents an unparalleled opportunity for upper atmosphere radiance data assimilation. Assimilation of the Lyman-Birge-Hopfield (LBH) band emissions can be formulated in a similar fashion to lower atmosphere radiance data assimilation approaches. To provide a proof-of-concept for such an approach, this paper presents assimilation experiment ...

Cantrall, Clayton; Matsuo, Tomoko; Solomon, Stanley;

YEAR: 2019     DOI: 10.1029/2019JA026910

Effects on the equatorial and low latitude thermosphere and ionosphere during the 19\textendash22 December 2015 geomagnetic storm period

In this paper, the critical frequency of F2 layer (foF2) and their peak height (hmF2) recorded at equatorial and low latitude stations of the South American sector were analyzed during the 19\textendash22 December 2015 geomagnetic storm period. We have observed initially decreases of foF2 at equatorial and low latitudes over the North crest of the equatorial ionization anomaly (EIA) and almost no effect over the South crest. These initial negative storm effects can be fully explained by the penetration of a westward elect ...

Mansilla, G.A.; Zossi, M.M.;

YEAR: 2019     DOI: 10.1016/j.asr.2019.09.025

Time-Dependent Response of the Terrestrial Exosphere to a Geomagnetic Storm

Recent observations of significant enhancements in exospheric hydrogen (H) emission in response to geomagnetic storms have been difficult to interpret in terms of the evolution of the underlying global, 3-D exospheric structure. In this letter, we report the first measurement of the timescales and spatial gradients associated with the exospheric response to a geomagnetic storm, which we derive from a novel, time-dependent tomographic analysis of H emission data. We find that global H density at 3 RE be ...

Cucho-Padin, Gonzalo; Waldrop, Lara;

YEAR: 2019     DOI: 10.1029/2019GL084327

Global-Scale Observations of the Equatorial Ionization Anomaly

The National Aeronautics and Space Administration Global-scale Observations of the Limb and Disk ultraviolet spectrograph has been imaging the equatorial ionization anomaly (EIA), regions of the ionosphere with enhanced electron density north and south of the magnetic equator, since October 2018. The initial 3 months of observations was during solar minimum conditions, and they included observations in December solstice of unanticipated variability and depleted regions. Depletions are seen on most nights, in contrast to e ...

Eastes, R.; Solomon, S.; Daniell, R.; Anderson, D.; Burns, A.; England, S.; Martinis, C.; McClintock, W.;

YEAR: 2019     DOI: 10.1029/2019GL084199

Ionospheric parameters in the European sector during the magnetic storm of August 25\textendash26, 2018

Variations of ionospheric parameters Total Electron Content (TEC) by GNSS, critical frequency (foF2) by vertical sounding and electron density (Ne) by low-altitude satellite were studied at high, mid and low latitudes of the European sector during the magnetic storm of August 25\textendash26, 2018. During the main phase of the storm the ionospheric F2-layer was under the positive disturbance at mid and low latitudes. Then the transition from the positive to negative ΔfoF2 values occurred at all latitudes. The recovery ph ...

Blagoveshchensky, D.V.; Sergeeva, M.A.;

YEAR: 2019     DOI: 10.1016/j.asr.2019.07.044

The OI-135.6~nm Nighttime Emission in ICON-FUV Images: A New Tool for the Observation of Classical Medium-Scale Traveling Ionospheric Disturbances?

The National Aeronautics and Space Administration Ionospheric Connection Explorer (ICON) mission will study the close relationship between the ionosphere, the atmospheric weather, and space weather using in situ and remote sensing instruments proving plasma density, temperature, ion drift velocity, and thermospheric wind velocity over the equatorial region. In particular, the far ultraviolet (FUV) instrument will image the terrestrial limb in two wavelength channels. During nighttime, only the channel characterizing the b ...

Wautelet, G.; Hubert, B.; erard, J.-C.; Immel, T.;

YEAR: 2019     DOI: 10.1029/2019JA026930

New Aspects of the Ionospheric Behavior Over Millstone Hill During the 30-Day Incoherent Scatter Radar Experiment in October 2002

The geomagnetic storm-driven ionospheric changes and the involved processes are interesting and challenging topics in understanding and predicting the ionosphere. In this study we investigate the response of the ionosphere to geomagnetic disturbances during the 30-day incoherent scatter radar measurements conducted at Millstone Hill (42.6\textdegreeN, 71.5\textdegreeW) from 4 October to 4 November 2002. During geomagnetically disturbed periods, while the peak electron density of the F2 layer (NmF2) and total electron cont ...

Liu, Libo; Le, Huijun; Chen, Yiding; Zhang, Ruilong; Wan, Weixing; Zhang, Shun-Rong;

YEAR: 2019     DOI: 10.1029/2019JA026806

An Opposite Response of the Low-Latitude Ionosphere at Asian and American Sectors During Storm Recovery Phases: Drivers From Below or Above

n this study, we focus on the recovery phase of a geomagnetic storm that happened on 6\textendash11 September 2017. The ground-based total electron content data, as well as the F region in situ electron density, measured by the Swarm satellites show an interesting feature, revealing at low and equatorial latitudes on the dayside ionosphere prominent positive and negative responses at the Asian and American longitudinal sectors, respectively. The global distribution of thermospheric O/N2 ratio measured ...

Xiong, Chao; Lühr, Hermann; Yamazaki, Yosuke;

YEAR: 2019     DOI: 10.1029/2019JA026917

Response of ionosphere over Korea and adjacent areas to 17 March 2015 geomagnetic storm

Assimilation of Multiple Data Types to a Regional Ionosphere Model With a 3D-Var Algorithm (IDA4D)

For the purpose of building a regional (bound 20\textendash60\textdegreeN in latitude and 110\textendash160\textdegreeE in longitude) ionospheric nowcast model, we investigated the performance of IDA4D (Ionospheric Data Assimilation Four-Dimension) technique considering International Reference Ionosphere model as the background. The data utilized in assimilation were slant total electron content (STEC) from 27 ground GPS (Global Positioning System) receiver stations and NmF2 (ionospheric F2 peak density) from five ionoson ...

Mengist, Chalachew; Ssessanga, Nicholas; Jeong, Se-Heon; Kim, Jeong-Heon; Kim, Yong; Kwak, Young-Sil;

YEAR: 2019     DOI: 10.1029/2019SW002159

Deriving Thermospheric Temperature From Observations by the Global Ultraviolet Imager on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics Satellite

This paper reports a preliminary result for estimating thermospheric temperature around 155 km from the N2 Lyman-Birge-Hopfield bands observed by TIMED/Global Ultraviolet Imager (GUVI). Atmospheric Ultraviolet Radiance Integrated Code model (Strickland et al., 1999, calculations indicate that the intensity ratio in the N2 Lyman-Birge-Hopfield (0,0) and (1,0) bands at 144.5- ...

Zhang, Yongliang; Paxton, Larry; Schaefer, Robert;

YEAR: 2019     DOI: 10.1029/2018JA026379

Imaging of the Daytime Ionospheric Equatorial Arcs With Extreme and Far Ultraviolet Airglow

We present the first global images of the daytime ionosphere equatorial arcs as manifested in the 83.4-nm airglow. These images were collected by the Limb-Imaging Ionospheric and Thermospheric Extreme-Ultraviolet Spectrograph that commenced operations on the International Space Station in early 2017. We compare these to simultaneous images of the ionospheric radiative recombination airglow at 135.6 nm measured between 250- and 350-km tangent altitudes, where the emission is generated primarily by radiative recombination o ...

Stephan, A.; Finn, S.; Cook, T.; Geddes, G.; Chakrabarti, S.; Budzien, S.;

YEAR: 2019     DOI: 10.1029/2019JA026624

Ionospheric disturbances at low and mid-low latitudes of the South American sector during the March 2015 great storm

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