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Christine Amory-mazaudier - One of the best experts on this subject based on the ideXlab platform.
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Ionospheric Disturbance Dynamo Associated to coronal hole during Geomagnetic Storm 1-5 August 2002
2016Co-Authors: Ibrahim Fathy, Christine Amory-mazaudier, A. M. MahrousAbstract:In this paper we study the Ionosphericmagnetic Disturbance during a magnetic storm on 2 August 2002 associated to a coronal hole. The Earth was under the influence of a high speed solar wind and IMF was southward. We separate the magnetic Disturbance associated to the Ionospheric Disturbance dynamo (Ddyn) from the magnetic Disturbance associated to the prompt penetration of magnetospheric electric field (DP2).We used three Stations (AAE, GUA and HUA) from INTERMAGNET Magnetometers in the equatorial regions at different longitude sectors (African, Asian and American respectively). At the beginning of the storm our data highlights the effect of the prompt penetration of the magnetosphere electric field (DP2). During the recovery phase of the storm, we observe the signature of Ionospheric Disturbance dynamo due to wind produced by Joule heating in the auroral zone. It is the first time that we observe an anti-Sq circulation on magnetic data in agreement with the Blanc and Richmonds model of Ionospheric Disturbance dynamo. The strongest effect is observed in the American sector
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Sun Earth Connections
2016Co-Authors: Christine Amory-mazaudierAbstract:Sun and Earth : Variabilities The Main Dynamos Solar dynamo Solar wind magnetosphere dynamo Ionospheric dynamo Earths dynamo The Electric current systems Magnetospheric current systems Ionospheric current systems Electrodynamic coupling between high and low latitudes PPEF : Prompt penetration of magnetospheric convection DDEF : Ionospheric Disturbance dynamo
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Planetary magnetic signature of the storm wind Disturbance dynamo
2015Co-Authors: Currents Ddyn, Minh Le Huy, Christine Amory-mazaudierAbstract:[1] During magnetic storms, Joule heating and ion drag, in auroral zones, strongly influence the circulation of thermospheric neutral winds. Joule heating produces equatorward neutral winds at F-region heights with return flow at E-region altitudes around the equator, the so-called Hadley cell. The modified thermospheric circulation produces upwelling of molecule-enriched air at high latitudes and global changes in the atmospheric composition. The equatorward neutral winds extending from the auroral zone to mid and low latitudes through the Coriolis force create westward storm wind which drives an equatorward dynamo current. In this paper, we detect for the first time, in the three longitude sectors, the planetary magnetic signature (Ddyn) of Ionospheric Disturbance dynamo with its main features: (1) the decrease of the equatorial electrojet due to a westward electric current flow opposite to the regular eastward current flow and (2) the equatorward Ionospheric Disturbance dynamo currents at midlatitudes. Citation: Le Huy, M., and C. Amory-Mazaudier (2008), Planetary magnetic signature of the storm wind Disturbance dynam
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Ionospheric Disturbance dynamo associated to a coronal hole: Case study of 5-10 April 2010
Journal of Geophysical Research Space Physics, 2014Co-Authors: Ibrahim Fathy, Christine Amory-mazaudier, A. Fathy, A. M. Mahrous, K. Yumoto, E. GhamryAbstract:In this paper we study the planetary magnetic Disturbance during the magnetic storm occurring on 5 April 2010 associated with high-speed solar wind stream due to a coronal hole following a coronal mass ejection. We separate the magnetic Disturbance associated to the Ionospheric Disturbance dynamo (Ddyn) from the magnetic Disturbance associated to the prompt penetration of magnetospheric electric field (DP2). This event exhibits different responses of Ionospheric Disturbance dynamo in the different longitude sectors (European-African, Asian, and American). The strongest effect is observed in the European-African sector. The Ddyn Disturbance reduces the amplitude of the daytime H component at low latitudes during four consecutive days in agreement with the Blanc and Richmond's model of Ionospheric Disturbance dynamo. The amplitude of Ddyn decreased with time during the 4 days. We discuss its diverse worldwide effects. The observed signature of magnetic Disturbance process in specific longitude sector is strongly dependent on which Earth's side faces the magnetic storms (i.e., there is a different response depending on which longitude sector is at noon when the SSC hits). Finally, we determined an average period of 22 h for Ddyn using wavelet analysis.
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Planetary magnetic signature of the storm wind Disturbance dynamo currents: Ddyn
Journal of Geophysical Research, 2008Co-Authors: Christine Amory-mazaudierAbstract:[1] During magnetic storms, Joule heating and ion drag, in auroral zones, strongly influence the circulation of thermospheric neutral winds. Joule heating produces equatorward neutral winds at F-region heights with return flow at E-region altitudes around the equator, the so-called Hadley cell. The modified thermospheric circulation produces upwelling of molecule-enriched air at high latitudes and global changes in the atmospheric composition. The equatorward neutral winds extending from the auroral zone to mid and low latitudes through the Coriolis force create westward storm wind which drives an equatorward dynamo current. In this paper, we detect for the first time, in the three longitude sectors, the planetary magnetic signature (Ddyn) of Ionospheric Disturbance dynamo with its main features: (1) the decrease of the equatorial electrojet due to a westward electric current flow opposite to the regular eastward current flow and (2) the equatorward Ionospheric Disturbance dynamo currents at midlatitudes.
M Ostrowski - One of the best experts on this subject based on the ideXlab platform.
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studies of a sudden Ionospheric Disturbance using the schumann resonances
URSI Atlantic Radio Science Conference, 2015Co-Authors: M Dyrda, Andrzej Kulak, Janusz Mlynarczyk, M OstrowskiAbstract:Extremely low frequency (ELF) electromagnetic waves in the Earth-ionosphere cavity are generated mainly by lightning discharges, originating from the tropical thunderstorm centres. The Earth-ionosphere spherical cavity forms a global resonator for the ELF waves, as predicted by Schumann in 1952. The resonance and the propagation properties of the ELF waves depend on the physical properties of the cavity. The lower Ionospheric layers are created by the UV radiation form the Sun. They are modulated by the Sun's 11-year cycle, but sometimes the rapid changes are caused by the solar flares and related sudden Ionospheric Disturbance (SID) phenomena. During the SID event the development of the Ionospheric D layer is observed, which leads to strong damping of the radio waves in the high frequency (HF) band. However, for the ELF waves the attenuation rate decreases significantly and the changes in the resonant frequencies should be observed.
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novel analysis of a sudden Ionospheric Disturbance using schumann resonance measurements
Journal of Geophysical Research, 2015Co-Authors: M Dyrda, Andrzej Kulak, Janusz Mlynarczyk, M OstrowskiAbstract:A spherical cavity between Earth and the lower ionosphere forms a global resonator for Extremely Low Frequency electromagnetic waves. Constant thunderstorm activity leads to the formation of a resonance field in the cavity, known as the Schumann resonance. Solar flare generated Sudden Ionospheric Disturbances (SID) modify the ionosphere affecting the ground-based radio communication systems. They are also expected to modify radiowave propagation in the cavity. In this paper, the Schumann Resonance spectral decomposition method is used for the first time to study the cavity resonance frequencies during the SID accompanying a strong X2.1 solar flare. We analyzed rapid changes in the frequencies and Q factors of the first five resonance modes using a 5 min timescale. The observed frequency shifts were compared to the ionizing solar flare fluxes in the UV, X-ray, and high-energy γ rays.
Yuichi Otsuka - One of the best experts on this subject based on the ideXlab platform.
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Observational evidence of interaction between Equatorial Plasma Bubble, Medium-scale Traveling Ionospheric Disturbances, and Midnight Brightness Wave at low latitudes
2020Co-Authors: C. A. O. B. Figueiredo, Yuichi Otsuka, Kazuo Shiokawa, Cristiano Max Wrasse, Hisao Takahashi, Ricardo Arlen Buriti, Igo Paulino, D. BarrosAbstract:An interesting interaction between equatorial plasma bubbles (EPBs), medium-scale traveling Ionospheric Disturbance (MSTID), and midnight brightness wave (MBW) were observed at Cachoeira Paulista, ...
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disappearance of equatorial plasma bubble after interaction with mid latitude medium scale traveling Ionospheric Disturbance
Geophysical Research Letters, 2012Co-Authors: Yuichi Otsuka, K Shiokawa, T OgawaAbstract:[1] We report simultaneous observations of an equatorial plasma bubble and a Medium-Scale Traveling Ionospheric Disturbance (MSTID) in 630-nm airglow images taken with an all-sky airglow imager at Shigaraki (34.9°N, 136.1°E; dip angle of the geomagnetic field ∼49°), Japan. Clear depletion of the 630-nm airglow intensity was observed as the equatorial plasma bubble propagated eastward, whereas the MSTID, which had a wavefront aligned from northwest to southeast, propagated southwestward. This result indicates that MSTIDs do not propagate at the same velocity as the ambient plasma, which is clearly shown by the eastward motion of the plasma bubbles. We found that the airglow depletion caused by the plasma bubble disappeared when the plasma bubble encountered the MSTID. The plasma depletion could be filled with ambient rich plasma that moved into the plasma-depleted region byE × B drift associated with the MSTID, indicating that MSTIDs are accompanied by electric field perturbations.
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long distance propagation of Ionospheric Disturbance generated by the 2011 off the pacific coast of tohoku earthquake
Earth Planets and Space, 2011Co-Authors: Chiahung Chen, Hofang Tsai, Takuya Tsugawa, M. Nishioka, A. Saito, Yuichi Otsuka, M. MatsumuraAbstract:Propagation of the initial Ionospheric total electron content (TEC) Disturbances generated by the 2011 off the Pacific coast of Tohoku Earthquake at 05:46:23 UT on March 11, 2011, was investigated with ground-based Global Positioning System (GPS) receivers in the east-Asian region. It was found that the initial Ionospheric Disturbance formed a zonal wave front after the earthquake occurrence. Four zonal wave fronts of this initial Ionospheric Disturbance were observed to travel southward from Japan to Taiwan with a velocity of about 1,000– 1,700 m/s. This study further found that the direction of the wave vector rotated from the south-southwest to the south-southeast as it traveled from Japan to Taiwan. The meridional propagation of the coseismic Ionospheric Disturbances is consistent with those observed after previous intense earthquakes. The temporal evolutions of initial Ionospheric Disturbances, after the earthquake, near the epicenter was observed in two-dimensions. The directivity of the Disturbances was caused by a geomagnetic field effect.
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statistical study of relationship between medium scale traveling Ionospheric Disturbance and sporadic e layer activities in summer night over japan
Journal of Atmospheric and Solar-Terrestrial Physics, 2008Co-Authors: Yuichi Otsuka, T Ogawa, T Tani, T Tsugawa, Akinori SaitoAbstract:Abstract We investigate the relationship between medium-scale traveling Ionospheric Disturbance (MSTID) and sporadic E ( E s ) layer activities in summer nights by analyzing total electron content (TEC) data obtained from a global positioning system (GPS) network in Japan and ionosonde data obtained at Kokubunji, Japan during May–August in 2001–2005. MSTID activity is defined as δ I / I ¯ , where δ I is standard deviation of the TEC perturbations over Kokubunji within 1 h, and I ¯ is the background TEC. By analyzing nighttime-averaged (19-02 LT) values of MSTID activity and E s layer parameters, we find that the MSTID activity is closely correlated with f 0 E s and f 0 E s - f b E s . This result suggests that MSTID and the spatial structures of E s layer could be generated by an electro-dynamical coupling process between the E s layer and F region through polarization electric fields. Furthermore, we suggest that the appearance of the E s layer in the summer hemisphere could play an important role in generating MSTIDs in both hemispheres.
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Ground observation and AMIE‐TIEGCM modeling of a storm‐time traveling Ionospheric Disturbance
Journal of Geophysical Research: Space Physics, 2007Co-Authors: Kazuo Shiokawa, Yuichi Otsuka, Tadahiko Ogawa, Masayuki Yamamoto, Nozomu Nishitani, Natsuo SatoAbstract:[1] This paper reports the first comparison between comprehensive observations of equatorward moving traveling Ionospheric Disturbance at midlatitudes and thermospheric general circulation model with high-latitude energy input based on data assimilation. A prominent traveling Ionospheric Disturbance (TID) was observed during the major magnetic storm of 31 March 2001. The TID propagated from north to south over Japan with phase speeds of 370–640 m/s. The assimilative mapping of Ionospheric electrodynamics (AMIE) technique was used as input to the thermosphere-ionosphere-electrodynamics general circulation model (TIEGCM) to investigate generation and propagation of the observed TID. In the model, two Joule heating enhancements in the high-latitude dayside sector produced two distinct traveling atmospheric waves (TADs), which propagated to Japan in the midnight sector as enhancements in thermospheric temperature and southward wind speed. The phase speed of the TADs was much faster (∼1100 m/s) in the model, probably due to the overestimation of Joule heating in the model. The second TAD corresponds to the observed prominent TID, while signatures of the first TAD were also seen in the observed ionosonde data. The observed TID was characterized by a decrease in southward wind speed, causing a significant F-layer height decrease and a temporal enhancement of F-layer peak density. These characteristics were reproduced by the model as a rarefaction of the second TAD. The temporal enhancement of F-layer peak density was because of the vertical shear of meridional wind. The absolute value of F-layer electron density in the model was several factors smaller than that observed, probably because of the underestimation of the supply of O+ ions from the plasmasphere.
Andrzej Kulak - One of the best experts on this subject based on the ideXlab platform.
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studies of a sudden Ionospheric Disturbance using the schumann resonances
URSI Atlantic Radio Science Conference, 2015Co-Authors: M Dyrda, Andrzej Kulak, Janusz Mlynarczyk, M OstrowskiAbstract:Extremely low frequency (ELF) electromagnetic waves in the Earth-ionosphere cavity are generated mainly by lightning discharges, originating from the tropical thunderstorm centres. The Earth-ionosphere spherical cavity forms a global resonator for the ELF waves, as predicted by Schumann in 1952. The resonance and the propagation properties of the ELF waves depend on the physical properties of the cavity. The lower Ionospheric layers are created by the UV radiation form the Sun. They are modulated by the Sun's 11-year cycle, but sometimes the rapid changes are caused by the solar flares and related sudden Ionospheric Disturbance (SID) phenomena. During the SID event the development of the Ionospheric D layer is observed, which leads to strong damping of the radio waves in the high frequency (HF) band. However, for the ELF waves the attenuation rate decreases significantly and the changes in the resonant frequencies should be observed.
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novel analysis of a sudden Ionospheric Disturbance using schumann resonance measurements
Journal of Geophysical Research, 2015Co-Authors: M Dyrda, Andrzej Kulak, Janusz Mlynarczyk, M OstrowskiAbstract:A spherical cavity between Earth and the lower ionosphere forms a global resonator for Extremely Low Frequency electromagnetic waves. Constant thunderstorm activity leads to the formation of a resonance field in the cavity, known as the Schumann resonance. Solar flare generated Sudden Ionospheric Disturbances (SID) modify the ionosphere affecting the ground-based radio communication systems. They are also expected to modify radiowave propagation in the cavity. In this paper, the Schumann Resonance spectral decomposition method is used for the first time to study the cavity resonance frequencies during the SID accompanying a strong X2.1 solar flare. We analyzed rapid changes in the frequencies and Q factors of the first five resonance modes using a 5 min timescale. The observed frequency shifts were compared to the ionizing solar flare fluxes in the UV, X-ray, and high-energy γ rays.
K Shiokawa - One of the best experts on this subject based on the ideXlab platform.
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www.ann-geophys.net/27/2399/2009/ © Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License.
2016Co-Authors: A. Koustov, K Shiokawa, N. Nishitani, P. V. Ponomarenko, S. Suzuki, B. M. Shevtsov, J. W. MacdougallAbstract:Joint observations of a traveling Ionospheric Disturbance with the Paratunka OMTI camera and the Hokkaido HF rada
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disappearance of equatorial plasma bubble after interaction with mid latitude medium scale traveling Ionospheric Disturbance
Geophysical Research Letters, 2012Co-Authors: Yuichi Otsuka, K Shiokawa, T OgawaAbstract:[1] We report simultaneous observations of an equatorial plasma bubble and a Medium-Scale Traveling Ionospheric Disturbance (MSTID) in 630-nm airglow images taken with an all-sky airglow imager at Shigaraki (34.9°N, 136.1°E; dip angle of the geomagnetic field ∼49°), Japan. Clear depletion of the 630-nm airglow intensity was observed as the equatorial plasma bubble propagated eastward, whereas the MSTID, which had a wavefront aligned from northwest to southeast, propagated southwestward. This result indicates that MSTIDs do not propagate at the same velocity as the ambient plasma, which is clearly shown by the eastward motion of the plasma bubbles. We found that the airglow depletion caused by the plasma bubble disappeared when the plasma bubble encountered the MSTID. The plasma depletion could be filled with ambient rich plasma that moved into the plasma-depleted region byE × B drift associated with the MSTID, indicating that MSTIDs are accompanied by electric field perturbations.
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thermospheric wind during a storm time large scale traveling Ionospheric Disturbance
Journal of Geophysical Research, 2003Co-Authors: K Shiokawa, Yuichi Otsuka, Masayuki Yamamoto, T Ogawa, Seiji Kawamura, S Fukao, Takuji Nakamura, Toshitaka Tsuda, K IgarashiAbstract:[1] A prominent large-scale traveling Ionospheric Disturbance (LSTID) was observed in Japan during the major magnetic storm (Dst ∼ −358 nT) of 31 March 2001. It was detected as enhancements of the 630-nm airglow and foF2, GPS-TEC variations, and a decrease in F-layer virtual height at 1700–1900 UT (0200–0400 LT). It moved equatorward with a speed of ∼600 m/s. The decrease in the F-layer height was also detected by the MU radar at Shigaraki. Thermospheric wind variations were observed by the MU radar through ion drift measurement and by a Fabry-Perot interferometer (FPI) through a Doppler shift of the 630-nm airglow line at Shigaraki. The wind data show a turn of the meridional wind from −94 m/s (equatorward) to +44 m/s (poleward) during the LSTID, indicating that an intense poleward wind in the thermosphere passed over Shigaraki as an atmospheric gravity wave and caused the observed Ionospheric features of the LSTID. Intense poleward wind was also detected at mesospheric altitudes (95–100 km) by the MU radar (through meteor echoes) and by the FPI (through the 558-nm airglow) with a delay of ∼2 hours from the thermospheric wind, indicating downward phase progression of the wave. Generation of the observed poleward wind in the auroral zone was investigated using magnetic field data and auroral energy input estimated by the assimilative mapping of Ionospheric electrodynamics (AMIE) technique. We suggest that simple atmospheric heating and/or the Lorentz force in the auroral zone do not explain the observed poleward wind enhancement.
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ground and satellite observations of nighttime medium scale traveling Ionospheric Disturbance at midlatitude
Journal of Geophysical Research, 2003Co-Authors: K Shiokawa, Yuichi Otsuka, T Ogawa, C Ihara, F J RichAbstract:[1] We have investigated a nighttime medium-scale traveling Ionospheric Disturbance (MSTID) observed by an airglow imager at Shigaraki (34.9°N, 25.4°MLAT), Japan, on 17 May 2001. The structure was identified in the airglow images of OI (630.0 nm and 777.4 nm) as NW-SE band structures (horizontal wavelength: 230 km) moving southwestward with a velocity of 50 m/s. Neutral wind velocity was measured simultaneously from the Doppler shift of the 630.0-nm emission by a Fabry-Perot interferometer at Shigaraki. From these parameters, we performed model calculations of MSTIDs generated by gravity waves and by an oscillating electric field. We found that for the case of gravity waves, the estimated vertical wavelength was too small to explain the observed amplitudes of airglow intensity. For the case of the electric field, we found that an electric field oscillation of ∼1.2 mV/m was sufficient to reproduce the observed airglow amplitudes. This modeled electric field was comparable to that observed by the DMSP F15 satellite as it passed over Shigaraki during our observing period on 17 May 2001. The DMSP ion drift data show that the oscillation of the polarization electric field correlated with the MSTID structure in the airglow image, suggesting that the polarization electric field plays an important role in the generation of MSTIDs.
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a large scale traveling Ionospheric Disturbance during the magnetic storm of 15 september 1999
Journal of Geophysical Research, 2002Co-Authors: K Shiokawa, Yuichi Otsuka, N. Balan, T Ogawa, K Igarashi, A J Ridley, Delores J Knipp, Akinori Saito, K. YumotoAbstract:enhancement of GPS total electron content (� 1.0 � 10 16 m � 2 ). Multipoint and imaging observations of these parameters show that the LSTID moved equatorward over Japan with a velocity of � 400–450 m/s. From a comparison with the Sheffield University Plasmasphere-Ionosphere Model (SUPIM) we conclude that an enhancement (250–300 m/s) of poleward neutral wind (that is propagating equatorward) caused these observational features of the LSTID at midlatitudes. To investigate generation of the LSTID by auroral energy input, we have used auroral images obtained by the Polar UVI instrument, magnetic field variations obtained at multipoint ground stations, and the empirical Joule heating rate calculated by the assimilative mapping of Ionospheric electrodynamics (AMIE) technique. Intense auroral energy input was observed at 0800–1100 UT (4–6 hours before the LSTID), probably causing equatorward neutral wind at lower latitudes. It is likely that the poleward wind pulse that caused the observed LSTID was generated associated with the cessation of this equatorward wind. The effect of Lorentz force is also discussed. INDEX TERMS: 0310 Atmospheric Composition and Structure: Airglow and aurora; 2427 Ionosphere: Ionosphere/atmosphere interactions (0335); 2435 Ionosphere: Ionospheric Disturbances; 2437 Ionosphere: Ionospheric dynamics; 2788 Magnetospheric Physics: Storms and substorms; KEYWORDS: large-scale traveling Ionospheric Disturbance, thermosphere–ionosphere coupling, magnetic storm, airglow imaging, GPS network, ionosonde
