Bibliography

Dynamics of ionospheric disturbances during the 17\textendash19 March 2015 geomagnetic storm over East Asia

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

The Storm Time Evolution of the Ionospheric Disturbance Plasma Drifts

In this paper, we use the C/NOFS and ROCSAT-1 satellites observations to analyze the storm time evolution of the disturbance plasma drifts in a 24\ h local time scale during three magnetic storms driven by long-lasting southward IMF B_z. The disturbance plasma drifts during the three storms present some common features in the periods dominated by the disturbance dynamo. The newly formed disturbance plasma drifts are upward and westward at night, and downward and eastward during daytime. Further, the disturbance plasma drifts are gradually evolved to present significant local time shifts. The westward disturbance plasma drifts gradually migrate from nightside to dayside. Meanwhile, the dayside downward disturbance plasma drifts become enhanced and shift to later local time. The local time shifts in disturbance plasma drifts are suggested to be mainly attributed to the evolution of the disturbance winds. The strong disturbance winds arisen around midnight can constantly corotate to later local time. At dayside the westward and equatorward disturbance winds can drive the F region dynamo to produce the poleward and westward polarization electric fields (or the westward and downward disturbance drifts). The present results indicate that the disturbance winds corotated to later local time can affect the local time features of the disturbance dynamo electric field.

Zhang, Ruilong; Liu, Libo; Le, Huijun; Chen, Yiding; Kuai, Jiawei;

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2017

YEAR: 2017     DOI: 10.1002/2017JA024637

Ionospheric-thermospheric UV tomography: 3. A multisensor technique for creating full-orbit reconstructions of atmospheric UV emission

We present the Volume Emission Rate Tomography (VERT) technique for inverting satellite-based, multisensor limb and nadir measurements of atmospheric ultraviolet emission to create whole-orbit reconstructions of atmospheric volume emission rate. The VERT approach is more general than previous ionospheric tomography methods because it can reconstruct the volume emission rate field irrespective of the particular excitation mechanisms (e.g., radiative recombination, photoelectron impact excitation, and energetic particle precipitation in auroras); physical models are then applied to interpret the airglow. The technique was developed and tested using data from the Special Sensor Ultraviolet Limb Imager and Special Sensor Ultraviolet Spectrographic Imager instruments aboard the Defense Meteorological Satellite Program F-18 spacecraft and planned for use with upcoming remote sensing missions. The technique incorporates several features to optimize the tomographic solutions, such as the use of a nonnegative algorithm (Richardson-Lucy, RL) that explicitly accounts for the Poisson statistics inherent in optical measurements, capability to include extinction effects due to resonant scattering and absorption of the photons from the lines of sight, a pseudodiffusion-based regularization scheme implemented between iterations of the RL code to produce smoother solutions, and the capability to estimate error bars on the solutions. Tests using simulated atmospheric emissions verify that the technique performs well in a variety of situations, including daytime, nighttime, and even in the challenging terminator regions. Lastly, we consider ionospheric nightglow and validate reconstructions of the nighttime electron density against Advanced Research Project Agency (ARPA) Long-range Tracking and Identification Radar (ALTAIR) incoherent scatter radar data.

Hei, Matthew; Budzien, Scott; Dymond, Kenneth; Nicholas, Andrew; Paxton, Larry; Schaefer, Robert; Groves, Keith;

Published by: Radio Science      Published on: 07/2017

YEAR: 2017     DOI: 10.1002/2015RS005887

Investigation of the Causes of the Longitudinal Variation of the Electron Density in the Weddell Sea Anomaly

This paper investigates and quantifies the causes of the Weddell Sea Anomaly (WSA), a region near the tip of South America extending from approximately 30\textdegree to 120\textdegreeW geographic longitude and 50\textdegree to 75\textdegreeS geographic latitude at solar minimum between 2007 and 2010. This region is unusual because the midnight peak electron density exceeds the midday peak electron density in summer. This study is far more quantitative than previous studies because, unlike other models, it assimilates selected data parameters to constrain a physical model in order to investigate other aspects of the data. It is shown that the commonly accepted explanation that the WSA is related to the magnetic field declination and inclination effects on the neutral wind does not explain the longitudinal variation of the electron density. Rather, longitudinal changes in the neutral winds and neutral densities are the most likely explanation for the WSA. These longitudinal wind and density changes are attributed to the varying latitudinal distance from the auroral zone energy input. No contributions from the plasmasphere or other sources are required. Furthermore, it is shown that a widely used empirical thermosphere density model overestimates the longitudinal changes in the WSA region.

Richards, P.; Meier, R.; Chen, Shih-Ping; Drob, D.; Dandenault, P.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2017

YEAR: 2017     DOI: 10.1002/2016JA023565

A severe negative response of the ionosphere to the intense geomagnetic storm on March 17, 2015 observed at mid- and low-latitude stations in the China zone

In this paper, the critical frequency of F2 layer of the ionosphere (foF₂₎ and the total electron content (TEC) recorded at mid- and low-latitude observation sites near 120\textdegreeE in the China zone were used to investigate the response to a severe geomagnetic storm on March 17, 2015 (the minimum Dst -223 nT at 23 UT). The results showed that the strong geomagnetic storm caused a massive effect on the ionosphere. The characteristics of foF₂ and TEC did not show obvious perturbation during the main phase. Severe depletion of foF₂ and TEC was observed at all stations during the storm recovery period. The maximum absolute discrepancy in TEC compared with the past 27-day average value was 78 TECU, and the minimum percentage deviations reached -71\% at Fuzhou (26.1\textdegreeN,\ 119.3\textdegreeE). The minimum percentage deviations of decrease in foF₂ reached -65\% at Sanya (18.1\textdegreeN,\ 109.3\textdegreeE) and Mohe (53.5\textdegreeN,\ 122.3\textdegreeE). This was an infrequent negative effect that foF₂ and TEC sustained throughout the day with extremely low level on March 18. The O/N₂ rate showed a distinct reduction on March 18 in the China zone, which may be mainly responsible for the severe depletion of foF₂ and TEC. The spread-F seemed to be developed at first but was then suppressed to some extent during the main phase. During the recovery phase, the spread-F was suppressed at Sanya, while it developed at Wuhan and Mohe. The disturbance electric fields and thermospheric circulation may contribute to this phenomenon.

Liu, Guoqi; Shen, Hua;

Published by: Advances in Space Research      Published on: 05/2017

YEAR: 2017     DOI: 10.1016/j.asr.2017.02.021

Regional differences of the ionospheric response to the July 2012 geomagnetic storm

The July 2012 geomagnetic storm is an extreme space weather event in solar cycle 24, which is characterized by a southward interplanetary geomagnetic field lasting for about 30\ h below -10\ nT. In this work, multiple instrumental observations, including electron density from ionosondes, total electron content (TEC) from Global Positioning System, Jason-2, and Gravity Recovery and Climate Experiment, and the topside ion concentration observed by the Defense Meteorological Satellite Program spacecraft are used to comprehensively present the regional differences of the ionospheric response to this event. In the Asian-Australian sector, an intensive negative storm is detected near longitude ~120\textdegreeE on 16 July, and in the topside ionosphere the negative phase is mainly existed in the equatorial region. The topside and bottomside TEC contribute equally to the depletion in TEC, and the disturbed electric fields make a reasonable contribution. On 15 July, the positive storm effects are stronger in the Eastside than in the Westside. The topside TEC make a major contribution to the enhancement in TEC for the positive phases, showing the important role of the equatorward neutral winds. For the American sector, the equatorial ionization anomaly intensification is stronger in the Westside than in the Eastside and shows the strongest feature in the longitude ~110\textdegreeW. The combined effects of the disturbed electric fields, composition disturbances, and neutral winds cause the complex storm time features. Both the topside ion concentrations and TEC reveal the remarkable hemispheric asymmetry, which is mainly resulted from the asymmetry in neutral winds and composition disturbances.

Kuai, Jiawei; Liu, Libo; Lei, Jiuhou; Liu, Jing; Zhao, Biqiang; Chen, Yiding; Le, Huijun; Wang, Yungang; Hu, Lianhuan;

Published by: Journal of Geophysical Research: Space Physics      Published on: 04/2017

YEAR: 2017     DOI: 10.1002/2016JA023844

A new auroral boundary determination algorithm based on observations from TIMED/GUVI and DMSP/SSUSI

An automatic auroral boundary determination algorithm is proposed in this study based on the partial auroral oval images from the Global Ultraviolet Imager (GUVI) aboard the Thermosphere\textendashIonosphere-Mesosphere Energetics and Dynamics satellite and the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) aboard the Defense Meteorological Satellite Program (DMSP F16). This algorithm based on the fuzzy local information C-means clustering segmentation can be used to extract the auroral oval poleward and equatorward boundaries from merged images with filled gaps from both GUVI and SSUSI. Both extracted poleward and equatorward boundary locations are used to fit the global shape of the auroral oval with a off-center quasi-elliptical fitting technique. Comparison of the extracted auroral oval boundaries with those identified from the DMSP SSJ observations demonstrates that this new proposed algorithm can reliably be used to construct the global configuration of auroral ovals under different geomagnetic activities at different local times. The statistical errors of magnetic latitudes of the fitted auroral oval boundaries were generally less than 3\textdegree at 2 sigma and indicate that the the fitted boundaries agree better with b2e and b5e than b1e and b6 boundaries. This proposed algorithm provides us with a useful tool to extract the global shape and position of the auroral oval from the partial auroral images.

Ding, Guang-Xing; He, Fei; Zhang, Xiao-Xin; Chen, Bo;

Published by: Journal of Geophysical Research: Space Physics      Published on: 01/2017

YEAR: 2017     DOI: 10.1002/jgra.v122.210.1002/2016JA023295

A new auroral boundary determination algorithm based on observations from TIMED/GUVI and DMSP/SSUSI

An automatic auroral boundary determination algorithm is proposed in this study based on the partial auroral oval images from the Global Ultraviolet Imager (GUVI) aboard the Thermosphere\textendashIonosphere-Mesosphere Energetics and Dynamics satellite and the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) aboard the Defense Meteorological Satellite Program (DMSP F16). This algorithm based on the fuzzy local information C-means clustering segmentation can be used to extract the auroral oval poleward and equatorward boundaries from merged images with filled gaps from both GUVI and SSUSI. Both extracted poleward and equatorward boundary locations are used to fit the global shape of the auroral oval with a off-center quasi-elliptical fitting technique. Comparison of the extracted auroral oval boundaries with those identified from the DMSP SSJ observations demonstrates that this new proposed algorithm can reliably be used to construct the global configuration of auroral ovals under different geomagnetic activities at different local times. The statistical errors of magnetic latitudes of the fitted auroral oval boundaries were generally less than 3\textdegree at 2 sigma and indicate that the the fitted boundaries agree better with b2e and b5e than b1e and b6 boundaries. This proposed algorithm provides us with a useful tool to extract the global shape and position of the auroral oval from the partial auroral images.

Ding, Guang-Xing; He, Fei; Zhang, Xiao-Xin; Chen, Bo;

Published by: Journal of Geophysical Research: Space Physics      Published on: 01/2017

YEAR: 2017     DOI: 10.1002/jgra.v122.210.1002/2016JA023295

Stationary depletions in thermospheric atomic oxygen concentration and mass density observed with WINDII, GUVI, GOCE and simulated by NRLMSISE-00

Multi-instrument observation of simultaneous polar cap auroras on open and closed magnetic field lines

Reidy, JA; Fear, RC; Whiter, DK; Lanchester, BS; Kavanagh, AJ; Paxton, LJ; Zhang, Y; Lester, Mark;

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

YEAR: 2017     DOI:

Dynamics of ionospheric disturbances during the 17—19 March 2015 geomagnetic storm over East Asia

Based on vertical sounding data from nine ionosondes located at 19–66N, 100–130E we investigated the latitude-temporal dynamics of ionospheric disturbances during the 17–19

Polekh, N; Zolotukhina, N; , Kurkin; Zherebtsov, G; Shi, J; Wang, G; Wang, Z;

Published by: Advances in Space Research      Published on:

YEAR: 2017     DOI: 10.1016/j.asr.2017.09.030

The scintillation prediction observations research task (SPORT): an international science mission using a cubesat

UV Airglow images from TIMED GUVI clearly showing the equatorial anomaly with embedded depletions that have penetrated through the F peak. Green, Red and Blue traces show the

Spann, James; Swenson, Charles; Durao, Otavio; Loures, Luis; Heelis, Rod; Bishop, Rebecca; Le, Guan; Abdu, Mangalathayil; Krause, Linda; Fry, Craig; , others;

Published by:       Published on:

YEAR: 2017     DOI:

New constraints on Ganymede s hydrogen corona: Analysis of Lyman-$\alpha$ emissions observed by HST/STIS between 1998 and 2014

Far-ultraviolet observations of Ganymede s atmospheric emissions were obtained with the Space Telescope Imaging Spectrograph (STIS) onboard of the Hubble Space Telescope (HST

Alday, Juan; Roth, Lorenz; Ivchenko, Nickolay; Retherford, Kurt; Becker, Tracy; Molyneux, Philippa; Saur, Joachim;

Published by: Planetary and Space Science      Published on:

YEAR: 2017     DOI: 10.1016/j.pss.2017.10.006

New constraints on Ganymede s hydrogen corona: Analysis of Lyman-$\alpha$ emissions observed by HST/STIS between 1998 and 2014

Far-ultraviolet observations of Ganymede s atmospheric emissions were obtained with the Space Telescope Imaging Spectrograph (STIS) onboard of the Hubble Space Telescope (HST

Alday, Juan; Roth, Lorenz; Ivchenko, Nickolay; Retherford, Kurt; Becker, Tracy; Molyneux, Philippa; Saur, Joachim;

Published by: Planetary and Space Science      Published on:

YEAR: 2017     DOI: 10.1016/j.pss.2017.10.006

MONITOR ionospheric network: two case studies on scintillation and electron content variability

The ESA MONITOR network is composed of high-frequency-sampling global navigation satellite systems (GNSS) receivers deployed mainly at low and high latitudes to study

eniguel, Yannick; Cherniak, Iurii; Garcia-Rigo, Alberto; Hamel, Pierrick; andez-Pajares, Manuel; Kameni, Roland; Kashcheyev, Anton; Krankowski, Andrzej; Monnerat, Michel; Nava, Bruno; , others;

Published by:       Published on:

YEAR: 2017     DOI: 10.5194/angeo-35-377-2017

MONITOR ionospheric network: two case studies on scintillation and electron content variability

The ESA MONITOR network is composed of high-frequency-sampling global navigation satellite systems (GNSS) receivers deployed mainly at low and high latitudes to study

eniguel, Yannick; Cherniak, Iurii; Garcia-Rigo, Alberto; Hamel, Pierrick; andez-Pajares, Manuel; Kameni, Roland; Kashcheyev, Anton; Krankowski, Andrzej; Monnerat, Michel; Nava, Bruno; , others;

Published by:       Published on:

YEAR: 2017     DOI: 10.5194/angeo-35-377-2017

Observations of the Weddell Sea Anomaly in the ground-based and space-borne TEC measurements

The Weddell Sea Anomaly (WSA) is a summer ionospheric anomaly, which is characterized by a greater nighttime ionospheric density than that in daytime in the region near the Weddell Sea. We investigate the WSA signatures in the ground-based TEC (vertical total electron content) by using GPS and GLONASS measurements of the dense regional GNSS networks in South America. We constructed the high-resolution regional TEC maps for December 2014–January 2015. The WSA effects of the TEC exceed the noontime values are registered starting from 17 LT, it reaches its maximum at 01–05 LT and starts to disappear after 09 LT.

Zakharenkova, Irina; Cherniak, Iurii; Shagimuratov, Irk;

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

YEAR: 2017     DOI: 10.1016/j.jastp.2017.06.014

Driving of Dramatic Geomagnetic Activity by Enhancement of Meso-Scale Polar-cap Flows

Lyons, Larry; Gallardo-Lacourt, Bea; Zou, Ying; Nishimura, Yukitoshi; Anderson, Phillip; Angelopoulos, VASSILIS; Ruohoniemi, Michael; Mitchell, Elizabeth; Paxton, Larry; Nishitani, Nozomu;

Published by:       Published on:

YEAR: 2017     DOI:

On the need for Artificial Intelligence and Advanced Test and Evaluation Methods for Space Exploration.

Scheidt, DH; Hibbitts, CA; Chen, MH; Bekker, DL; Paxton, LJ; , others;

Published by:       Published on:

YEAR: 2017     DOI:

On the need for Artificial Intelligence and Advanced Test and Evaluation Methods for Space Exploration.

Scheidt, DH; Hibbitts, CA; Chen, MH; Bekker, DL; Paxton, LJ; , others;

Published by:       Published on:

YEAR: 2017     DOI:

The 2017 Van Allen Lecture

Paxton, Larry; Cohen, Christina;

Published by:       Published on:

YEAR: 2017     DOI:

The scintillation prediction observations research task (sport) mission

Fry, G; Spann, James; Swenson, Charles; Durao, Otavio; Loures, Luis; Heelis, Rod; Bishop, Rebecca; Le, Guan; Abdu, Mangalathayli; Krause, Linda; , others;

Published by:       Published on:

YEAR: 2017     DOI:

Tidal and Ionospheric Contributions in GUVI O/N2 wave-4 Signals and Implications for F-region Plasma Density Variability

Oberheide, Jens; Krier, Christopher; Gan, Quan; Nischal, Nirmal; Zhang, Yongliang; Chang, Loren;

Published by:       Published on:

YEAR: 2017     DOI:

A severe negative response of the ionosphere to the intense geomagnetic storm on March 17, 2015 observed at mid-and low-latitude stations in the China zone

Liu, Guoqi; Shen, Hua;

Published by: Advances in Space Research      Published on:

YEAR: 2017     DOI:

The Scintillation Prediction Observations Research Task: A Multinational Science Mission Using a Cubesat

Spann, James; Swenson, Charles; Dur\~ao, Otavio; Loures, Luis; Heelis, Rod; Bishop, Rebecca; Le, Guan; Abdu, Mangalathayil; Krause, Linda; Denardin, Clezio; , others;

Published by:       Published on:

YEAR: 2017     DOI:

Studying the ionosphere response to severe geomagnetic storm in March 2015 according to Eurasian ionosonde chain

Shpynev, BG; Zolotukhina, NA; Polekh, NM; Chernigovskaya, MA; Ratovsky, KG; Belinskaya, Yu; Stepanov, AE; Bychkov, VV; Grigorieva, SA; Panchenko, VA; , others;

Published by: Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa      Published on:

YEAR: 2017     DOI:

Studying the ionosphere response to severe geomagnetic storm in March 2015 according to Eurasian ionosonde chain

Shpynev, BG; Zolotukhina, NA; Polekh, NM; Chernigovskaya, MA; Ratovsky, KG; Belinskaya, Yu; Stepanov, AE; Bychkov, VV; Grigorieva, SA; Panchenko, VA; , others;

Published by: Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa      Published on:

YEAR: 2017     DOI:

Direct observational evidence for disturbance dynamo on the daytime low-latitude ionosphere: A case study based on the 28 June 2013 space weather event

A case of the westward disturbance dynamo (DD) electric field, influencing the daytime equatorial and low-latitude ionosphere, during a geomagnetic storm that occurred on 28\textendash29 June 2013 is presented. The GPS total electron content (TEC) observations from a network of stations in the Indian equatorial, low and middle latitude regions along with the radio beacon TEC, ionosonde, and magnetic field observations are used to study the storm time behavior of the ionosphere. Negative ionospheric storm effects were seen over the low and middle latitudes during the storm time due to the presence of a westward DD electric field. Observations show that the suppression of the equatorial ionization anomaly (EIA) from the morning hours itself on 29 June 2013 took place due to the prevailing westward DD electric field, providing evidence for the model calculations by Balan et al. (2013). Simulations using the GITM model also agree well with our results. The present study gains importance as the direct observational evidences for disturbance dynamo effects on the daytime low-latitude ionosphere and the EIA are sparse, as it has been difficult to delineate it from the compositional disturbances.

Thampi, Smitha; Shreedevi, P.; Choudhary, R.; Pant, Tarun; Chakrabarty, D.; Sunda, S.; Mukherjee, S.; Bhardwaj, Anil;

Published by: Journal of Geophysical Research: Space Physics      Published on: 09/2016

YEAR: 2016     DOI: 10.1002/2016JA023037

The observation and simulation of ionospheric response to CIR/high-speed streams-induced geomagnetic activity on 4 April 2005

The ionospheric response to corotating interaction region (CIR)-induced geomagnetic activity on 4 April 2005 has been studied using in situ electron density measurements, ground GPS-total electron content (TEC) observations, and numerical simulations of the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). The case study resulted that the ionospheric positive response occurred from high to low latitudes. The positive effect at low latitudes could continue for 4 days, whereas at middle to high latitudes the disturbance mainly lasted only for 1 day. The modeled Ne and TEC from TIE-GCM had a good agreement with those from observations. The simulation results showed that penetration electric fields were responsible for the daytime positive response during the initial and main phases of the geomagnetic storm, while neutral winds were responsible for the presunset positive effects. The long-lasting positive storm effect during the storm recovery time at low latitudes was related to the thermospheric composition (O/N 2 ) changes during the storm event.

Chen, Yanhong; Wang, Wenbin; Qiu, Na; Liu, Siqing; Gong, Jiancun; Huang, Wengeng;

Published by: Radio Science      Published on: 08/2016

YEAR: 2016     DOI: 10.1002/rds.v51.810.1002/2015RS005937

High-latitude ionospheric irregularities: differences between ground- and space-based GPS measurements during the 2015 St. Patrick\textquoterights Day storm

We present an analysis of ionospheric irregularities at high latitudes during the 2015 St. Patrick\textquoterights Day storm. Our study used measurements from\ ~2700 ground-based GPS stations and GPS receivers onboard five low earth orbit (LEO) satellites\textemdashSwarm A, B and C, GRACE and TerraSAR-X\textemdashthat had close orbit altitudes of\ ~500\ km, and the Swarm in situ plasma densities. An analysis of the rate of TEC index (ROTI) derived from LEO\textendashGPS data, together with Swarm in situ plasma probe data, allowed us to examine the topside ionospheric irregularities and to compare them to the main ionospheric storm effects observed in ground-based GPS data. We observed strong ionospheric irregularities in the topside ionosphere during the storm\textquoterights main phase that were associated with storm-enhanced density (SED) formation at mid-latitudes and further evolution of the SED plume to the polar tongue of ionization (TOI). Daily ROTI maps derived from ground-based and LEO\textendashGPS measurements show the pattern of irregularities oriented in the local noon\textendashmidnight direction, which is a signature of SED/TOI development across the polar cap region. Analysis of the Swarm in situ plasma measurements revealed that, during the storm\textquoterights main phase, all events with extremely enhanced plasma densities (\>10⁶\ el/cm³) in the polar cap were observed in the Southern Hemisphere. When Swarm satellites crossed these enhancements, degradation of GPS performance was observed, with a sudden decrease in the number of GPS satellites tracked. Our findings indicate that polar patches and TOI structures in the topside ionosphere were predominantly observed in the Southern Hemisphere, which had much higher plasma densities than the Northern Hemisphere, where SED/TOI structures have already been reported earlier. LEO\textendashGPS data (ROTI and topside TEC) were consistent with these results.

Cherniak, Iurii; Zakharenkova, Irina;

Published by: Earth, Planets and Space      Published on: 07/2016

YEAR: 2016     DOI: 10.1186/s40623-016-0506-1

Ionospheric data assimilation with thermosphere-ionosphere-electrodynamics general circulation model and GPS-TEC during geomagnetic storm conditions

The main purpose of this paper is to investigate the effects of rapid assimilation-forecast cycling on the performance of ionospheric data assimilation during geomagnetic storm conditions. An ensemble Kalman filter software developed by the National Center for Atmospheric Research (NCAR), called Data Assimilation Research Testbed, is applied to assimilate ground-based GPS total electron content (TEC) observations into a theoretical numerical model of the thermosphere and ionosphere (NCAR thermosphere-ionosphere-electrodynamics general circulation model) during the 26 September 2011 geomagnetic storm period. Effects of various assimilation-forecast cycle lengths: 60, 30, and 10 min on the ionospheric forecast are examined by using the global root-mean-squared observation-minus-forecast (OmF) TEC residuals. Substantial reduction in the global OmF for the 10 min assimilation-forecast cycling suggests that a rapid cycling ionospheric data assimilation system can greatly improve the quality of the model forecast during geomagnetic storm conditions. Furthermore, updating the thermospheric state variables in the coupled thermosphere-ionosphere forecast model in the assimilation step is an important factor in improving the trajectory of model forecasting. The shorter assimilation-forecast cycling (10 min in this paper) helps to restrain unrealistic model error growth during the forecast step due to the imbalance among model state variables resulting from an inadequate state update, which in turn leads to a greater forecast accuracy.

Chen, C.; Lin, C.; Matsuo, T.; Chen, W.; Lee, I.; Liu, J; Lin, J.; Hsu, C.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2016

YEAR: 2016     DOI: 10.1002/2015JA021787

Ionospheric data assimilation with thermosphere-ionosphere-electrodynamics general circulation model and GPS-TEC during geomagnetic storm conditions

The main purpose of this paper is to investigate the effects of rapid assimilation-forecast cycling on the performance of ionospheric data assimilation during geomagnetic storm conditions. An ensemble Kalman filter software developed by the National Center for Atmospheric Research (NCAR), called Data Assimilation Research Testbed, is applied to assimilate ground-based GPS total electron content (TEC) observations into a theoretical numerical model of the thermosphere and ionosphere (NCAR thermosphere-ionosphere-electrodynamics general circulation model) during the 26 September 2011 geomagnetic storm period. Effects of various assimilation-forecast cycle lengths: 60, 30, and 10 min on the ionospheric forecast are examined by using the global root-mean-squared observation-minus-forecast (OmF) TEC residuals. Substantial reduction in the global OmF for the 10 min assimilation-forecast cycling suggests that a rapid cycling ionospheric data assimilation system can greatly improve the quality of the model forecast during geomagnetic storm conditions. Furthermore, updating the thermospheric state variables in the coupled thermosphere-ionosphere forecast model in the assimilation step is an important factor in improving the trajectory of model forecasting. The shorter assimilation-forecast cycling (10 min in this paper) helps to restrain unrealistic model error growth during the forecast step due to the imbalance among model state variables resulting from an inadequate state update, which in turn leads to a greater forecast accuracy.

Chen, C.; Lin, C.; Matsuo, T.; Chen, W.; Lee, I.; Liu, J; Lin, J.; Hsu, C.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2016

YEAR: 2016     DOI: 10.1002/2015JA021787

Middle- and low-latitude ionosphere response to 2015 St. Patrick\textquoterights Day geomagnetic storm

This paper presents a study of the St Patrick\textquoterights Day storm of 2015, with its ionospheric response at middle and low latitudes. The effects of the storm in each longitudinal sector (Asian, African, American, and Pacific) are characterized using global and regional electron content. At the beginning of the storm, one or two ionospheric positive storm effects are observed depending on the longitudinal zones. After the main phase of the storm, a strong decrease in ionization is observed at all longitudes, lasting several days. The American region exhibits the most remarkable increase in vertical total electron content (vTEC), while in the Asian sector, the largest decrease in vTEC is observed. At low latitudes, using spectral analysis, we were able to separate the effects of the prompt penetration of the magnetospheric convection electric field (PPEF) and of the disturbance dynamo electric field (DDEF) on the basis of ground magnetic data. Concerning the PPEF, Earth\textquoterights magnetic field oscillations occur simultaneously in the Asian, African, and American sectors, during southward magnetization of the B_z component of the interplanetary magnetic field. Concerning the DDEF, diurnal magnetic oscillations in the horizontal component H of the Earth\textquoterights magnetic field exhibit a behavior that is opposed to the regular one. These diurnal oscillations are recognized to last several days in all longitudinal sectors. The observational data obtained by all sensors used in the present paper can be interpreted on the basis of existing theoretical models.

Nava, B.; iguez-Zuluaga, Rodr\; Alazo-Cuartas, K.; Kashcheyev, A.; e, Migoya-Oru\; Radicella, S.M.; Amory-Mazaudier, C.; Fleury, R.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 03/2016

YEAR: 2016     DOI: 10.1002/2015JA022299

On the latitudinal changes in ionospheric electrodynamics and composition based on observations over the 76--77 E meridian from both hemispheres during a geomagnetic storm

The relative contributions of the composition disturbances and the disturbance electric fields in the redistribution of ionospheric plasma is investigated in detail by taking the case of a long-duration positive ionospheric storm that occurred during 18\textendash21 February 2014. GPS total electron content (TEC) data from the Indian Antarctic station, Bharti (69.4\textdegreeS, 76.2\textdegreeE geographic), the northern midlatitude station Hanle (32.8\textdegreeN, 78.9\textdegreeE geographic), northern low-latitude station lying in the vicinity of the anomaly crest, Ahmedabad (23.04\textdegreeN, 72.54\textdegreeE geographic, dip latitude 17\textdegreeN), and the geomagnetic equatorial station, Trivandrum (8.5\textdegreeN, 77\textdegreeE geographic, dip latitude 0.01\textdegreeS) are used in the study. These are the first simultaneous observations of TEC from Bharti and Hanle during a geomagnetic storm. The impact of the intense geomagnetic storm (Dst\~-130\ nT) on the southern hemisphere high-latitude station was a drastic reduction in the TEC (negative ionospheric storm) starting from around 0330 Indian standard time (IST) on 19 February which continued till 21 February, the maximum reduction in TEC at Bharti being \~35 TEC units on 19 February. In the northern hemisphere midlatitude and equatorial stations, a positive ionospheric storm started on 19 February at around 0900 IST and lasted for 3\ days. The maximum enhancement in TEC at Hanle was about \~25 TECU on 19 February while over Trivandrum it was \~10 TECU. This long-duration positive ionospheric storm provided an opportunity to assess the relative contributions of disturbance electric fields and composition changes latitudinally. The results indicate that the negative ionospheric storm over Bharti and the positive ionospheric storm over Hanle are the effect of the changes in the global wind system and the storm-induced composition changes. At the equatorial latitudes, the positive ionospheric storm was due to the interplay of prompt penetration electric field and disturbance dynamo electric field.

Shreedevi, P.; Thampi, Smitha; Chakrabarty, D.; Choudhary, R.; Pant, Tarun; Bhardwaj, Anil; Mukherjee, S.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 02/2016

YEAR: 2016     DOI: 10.1002/2015JA021841

Geomagnetic storms; High latitude low latitude coupling; Ionosphere; positive ionospheric storm

Thermospheric atomic oxygen concentrations from WINDII O+ (2P→ 2D) 732 nm emission: Comparisons with the NRLMSISE-00 and C-IAM models and with GUVI observations

Shepherd, Gordon; Cho, Young-Min; Fomichev, Victor; Martynenko, Oleg;

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

YEAR: 2016     DOI:

Thermospheric atomic oxygen concentrations from WINDII O+ (2P→ 2D) 732 nm emission: Comparisons with the NRLMSISE-00 and C-IAM models and with GUVI observations

Shepherd, Gordon; Cho, Young-Min; Fomichev, Victor; Martynenko, Oleg;

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

YEAR: 2016     DOI:

Studying Peculiarities of Ionospheric Response to the 2015 March 17-19 Geomagnetic Storm in East Asia: Observations and Simulation

Romanova, Elena; Zherebtsov, Gelii; Polekh, Nelya; Wang, Xiao; Wang, Guojun; Zolotukhina, Nina; Shi, Jiankui;

Published by: 41st COSPAR Scientific Assembly      Published on:

YEAR: 2016     DOI:

High-latitude ionospheric irregularities: differences between ground-and space-based GPS measurements during the 2015 St. Patrick’s Day storm

We present an analysis of ionospheric irregularities at high latitudes during the 2015 St. Patrick’s Day storm. Our study used measurements from ~2700 ground-based GPS stations and

Cherniak, Iurii; Zakharenkova, Irina;

Published by: Earth, Planets and Space      Published on:

YEAR: 2016     DOI: 10.1186/s40623-016-0506-1

Ionospheric Space Weather: Longitude Dependence and Lower Atmosphere Forcing

This monograph is the outcome of an American Geophysical Union Chapman Conference on longitude and hemispheric dependence of ionospheric space weather, including the

Fuller-Rowell, Timothy; Yizengaw, Endawoke; Doherty, Patricia; Basu, Sunanda;

Published by:       Published on:

YEAR: 2016     DOI:

RENU 2 UV Measurements of Atomic Oxygen in the Cusp Region

Fritz, Bruce; Lessard, Marc; Paxton, Larry; Cook, Timothy; Lynch, Kristina; Clemmons, James; Hecht, James; Hysell, David; Crowley, Geoff;

Published by:       Published on:

YEAR: 2016     DOI:

Multi-instrument observation of two different types of polar cap aurora occurring simultaneously during northward IMF

Reidy, Jade; Fear, Robert; Lanchester, Betty; Whiter, Daniel; Kavanagh, Andrew; Paxton, Larry; Zhang, Yongliang;

Published by:       Published on:

YEAR: 2016     DOI:

Middle-and low-latitude ionosphere response to 2015 St. Patrick's Day geomagnetic storm

Nava, B; iguez-Zuluaga, Rodr\; Alazo-Cuartas, K; Kashcheyev, A; e, Migoya-Oru\; Radicella, SM; Amory-Mazaudier, Christine; Fleury, Rolland;

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

YEAR: 2016     DOI: 10.1002/2015JA022299

Validating Local Responses in OVATION Prime-2013 and OVATION-SM with DMSP SSUSI

Mitchell, Elizabeth; Schaefer, Robert; Paxton, Larry;

Published by:       Published on:

YEAR: 2016     DOI:

DYNAMIC: A Decadal Survey and NASA Roadmap Mission

Paxton, Larry; Oberheide, Jens;

Published by:       Published on:

YEAR: 2016     DOI:

Ionospheric responses to geomagnetic storms during 2015-2016 at longitude 120° E in China

Chen, Yanhong; Tianjiao, Yuan; Hua, Shen; Liu, Siqing; Wengeng, Huang; Gong, Jiancun;

Published by:       Published on:

YEAR: 2016     DOI:

Ionospheric data assimilation and forecasting during storms

Chartier, Alex; Matsuo, Tomoko; Anderson, Jeffrey; Collins, Nancy; Hoar, Timothy; Lu, Gang; Mitchell, Cathryn; Coster, Anthea; Paxton, Larry; Bust, Gary;

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

YEAR: 2016     DOI:

SPORT: The Scintillation Prediction Observations Research Task

Spann, James; Swenson, Charles; Durao, Otavio; Loures, Luis; Heelis, Rod; Bishop, Rebecca; Le, Guan; Krause, Linda; Nardin, Clezio; Fonseca, Eloi; , others;

Published by:       Published on:

YEAR: 2016     DOI:

NASA Timed Guvi and Dmsp Ssusi Observations of the St. Patricks Day Storm of

Paxton, Larry; Zhang, Yongliang; Kil, Hyosub; Mitchell, Elizabeth; Schaefer, Robert;

Published by: 41st COSPAR Scientific Assembly      Published on:

YEAR: 2016     DOI:

Dependence of the high-latitude plasma irregularities on the auroral activity indices: a case study of 17 March 2015 geomagnetic storm

The magnetosphere substorm plays a crucial role in the solar wind energy dissipation into the ionosphere. We report on the intensity of the high-latitude ionospheric irregularities during one of the largest storms of the current solar cycle\textemdashthe St. Patrick\textquoterights Day storm of 17 March 2015. The database of more than 2500 ground-based Global Positioning System (GPS) receivers was used to estimate the irregularities occurrence and dynamics over the auroral region of the Northern Hemisphere. We analyze the dependence of the GPS-detected ionospheric irregularities on the auroral activity. The development and intensity of the high-latitude irregularities during this geomagnetic storm reveal a high correlation with the auroral hemispheric power and auroral electrojet indices (0.84 and 0.79, respectively). Besides the ionospheric irregularities caused by particle precipitation inside the polar cap region, evidences of other irregularities related to the storm enhanced density (SED), formed at mid-latitudes and its further transportation in the form of tongue of ionization (TOI) towards and across the polar cap, are presented. We highlight the importance accounting contribution of ionospheric irregularities not directly related with particle precipitation in overall irregularities distribution and intensity.

Cherniak, Iurii; Zakharenkova, Irina;

Published by: Earth, Planets and Space      Published on: 12/2015

YEAR: 2015     DOI: 10.1186/s40623-015-0316-x

Auroral hemispheric power index Auroral precipitation; geomagnetic storm; GPS; Ionosphere irregularities; ROTI