Equatorial ionospheric response to storm-time electric fields during two intense geomagnetic storms over the Brazilian region using a Disturbance Ionosphere indeX

2021 ◽  
pp. 105734
Author(s):  
G.A.S. Picanço ◽  
C.M. Denardini ◽  
P.A.B. Nogueira ◽  
P.F. Barbosa-Neto ◽  
L.C.A. Resende ◽  
...  
Keyword(s):  
Electric Fields ◽  
Geomagnetic Storms ◽  
Ionospheric Response

scholarly journals Effects of strong IMF <I>B<sub>z</sub></I> southward events on the equatorial and mid-latitude ionosphere

2009 ◽  
Vol 27 (3) ◽  
pp. 1175-1187 ◽  
Author(s):  
E. Astafyeva
Keyword(s):  
Electric Fields ◽  
Geomagnetic Storms ◽  
The Other ◽  
Negative Events ◽  
Equatorial Anomaly ◽  
Low Latitude ◽  
Sudden Drop ◽  
Ionospheric Response ◽  
Peak Structure ◽  
Low Latitude Ionosphere

Abstract. Dayside ionospheric response to five intense geomagnetic storms (Dst<−120 nT) that occurred in 2001–2005 was investigated by use of simultaneous TEC measurements by the CHAMP, SAC-C, TOPEX/Jason-1 satellites. Since the satellites passed over different longitudinal sectors and measured TEC in different range of altitudes, it was possible to obtain information about altitudinal and longitudinal ionosphere redistribution during these storms. Severe enhancements (up to ~350%) of the equatorial and mid-latitude TEC above ~430 km with concurrent traveling of the equatorial anomaly crests for a distance of 10–15° of latitude were observed during two of the five events analyzed here (6 November 2001 and 8 November 2004). This phenomenon, known as the dayside ionosphere uplift, or the "daytime super-fountain effect", occurred after sudden drop in IMF Bz and consequent penetration of the electric fields to the low-latitude ionosphere. However, the same order Bz negative events caused comparatively weak changes in the dayside TEC (up to ~80 TECU) during the other three events of 18 June 2003, 11 February 2004 and 24 August 2005. At the main phase of these storms there were mostly observed formation of the "typical" dual peak structure of the equatorial anomaly rather than the reinforcement of the fountain effect and the anomaly itself. Possible reasons and factors responsible for the development of the extreme ionosphere effects are discussed in the paper.

scholarly journals Total electron content responses to HILDCAAs and geomagnetic storms over South America

2017 ◽  
Vol 35 (6) ◽  
pp. 1309-1326 ◽  
Author(s):  
Patricia Mara de Siqueira Negreti ◽  
Eurico Rodrigues de Paula ◽  
Claudia Maria Nicoli Candido
Keyword(s):  
Solar Wind ◽  
South America ◽  
Total Electron Content ◽  
Geomagnetic Storm ◽  
Electric Fields ◽  
Geomagnetic Storms ◽  
Time Variability ◽  
Electron Content ◽  
Quiet Time ◽  
Total Electron

Abstract. Total electron content (TEC) is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs) and the longer-lasting ionospheric disturbance dynamo (DD) electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA) at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE) activity) events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013) the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O ∕ N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil) and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from  ∼  25 to 80 % (compared to quiet time) were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to solar wind forcing and considering the events studied here, this was the most important source of ionospheric responses. Furthermore, the most important source of TEC changes were the long-lasting PPEFs observed on August 2013, during the HILDCAA event. The importance of this study relies on the peculiarity of the region analyzed characterized by high declination angle and ionospheric gradients which are responsible for creating a complex response during disturbed periods.

Ionospheric response to the 17 March and 22 June 2015 geomagnetic storms over Wuhan region using GNSS-based tomographic technique

2021 ◽  
Vol 67 (1) ◽  
pp. 111-121
Author(s):  
Jian Feng ◽  
Yufeng Zhou ◽  
Yan Zhou ◽  
Shuaihe Gao ◽  
Chen Zhou ◽  
...  
Keyword(s):  
Geomagnetic Storms ◽  
Ionospheric Response ◽  
Tomographic Technique

scholarly journals Role of the magnetospheric and ionospheric currents in the generation of the equatorial scintillations during geomagnetic storms

2004 ◽  
Vol 22 (9) ◽  
pp. 3195-3202 ◽  
Author(s):  
L. Z. Biktash
Keyword(s):  
Solar Wind ◽  
Electric Fields ◽  
Ring Current ◽  
Geomagnetic Storms ◽  
Equatorial Ionosphere ◽  
Experimental Investigations ◽  
Polar Regions ◽  
Ionospheric Currents ◽  
Geomagnetic Variations ◽  
Activity Effect

Abstract. The equatorial ionosphere parameters, Kp, Dst, AU and AL indices characterized contribution of different magnetospheric and ionospheric currents to the H-component of geomagnetic field are examined to test the geomagnetic activity effect on the generation of ionospheric irregularities producing VLF scintillations. According to the results of the current statistical studies, one can predict near 70% of scintillations from Aarons' criteria using the Dst index, which mainly depicts the magnetospheric ring current field. To amplify Aarons' criteria or to propose new criteria for predicting scintillation characteristics is the question. In the present phase of the experimental investigations of electron density irregularities in the ionosphere new ways are opened up because observations in the interaction between the solar wind - magnetosphere - ionosphere during magnetic storms have progressed greatly. According to present view, the intensity of the electric fields and currents at the polar regions, as well as the magnetospheric ring current intensity, are strongly dependent on the variations of the interplanetary magnetic field. The magnetospheric ring current cannot directly penetrate the equatorial ionosphere and because of this difficulties emerge in explaining its relation to scintillation activity. On the other hand, the equatorial scintillations can be observed in the absence of the magnetospheric ring current. It is shown that in addition to Aarons' criteria for the prediction of the ionospheric scintillations, models can be used to explain the relationship between the equatorial ionospheric parameters, h'F, foF2, and the equatorial geomagnetic variations with the polar ionosphere currents and the solar wind.

scholarly journals Ionospheric Response to Strong Geomagnetic Storms During 2000–2005: An IMF Clock Angle Perspective

Radio Science ◽  
2020 ◽  
Vol 55 (9) ◽  
Author(s):  
Sumanjit Chakraborty ◽  
Sarbani Ray ◽  
Abhirup Datta ◽  
Ashik Paul
Keyword(s):  
Geomagnetic Storms ◽  
Ionospheric Response ◽  
Imf Clock Angle

scholarly journals Evidence of prompt penetration electric fields during HILDCAA events

2017 ◽  
Vol 35 (5) ◽  
pp. 1165-1176 ◽  
Author(s):  
Regia Pereira Silva ◽  
Jose Humberto Andrade Sobral ◽  
Daiki Koga ◽  
Jonas Rodrigues Souza
Keyword(s):  
Electric Fields ◽  
Cross Correlation ◽  
Geomagnetic Storms ◽  
Current System ◽  
Special Kind ◽  
Recovery Phase ◽  
Peak Height ◽  
Auroral Zone ◽  
Density Peak ◽  
Sinusoidal Oscillations

Abstract. High-intensity, long-duration continuous auroral electrojet (AE) activity (HILDCAA) events may occur during a long-lasting recovery phase of a geomagnetic storm. They are a special kind of geomagnetic activity, different from magnetic storms or substorms. Ionized particles are pumped into the auroral region by the action of Alfvén waves, increasing the auroral current system. The Dst index, however, does not present a significant downward swing as it occurs during geomagnetic storms. During the HILDCAA occurrence, the AE index presents an intense and continuous activity. In this paper, the response of Brazilian equatorial ionosphere is studied during three HILDCAA events that occurred in the year of 2006 (the descending phase of solar cycle 23) using the digisonde data located at São Luís, Brazil (2.33° S, 44.2° W; dip latitude 1.75° S). Geomagnetic indices and interplanetary parameters were used to calculate a cross-correlation coefficient between the Ey component of the interplanetary electric field and the F2 electron density peak height variations during two situations: the first of them for two sets daytime and nighttime ranges, and the second one for the time around the pre-reversal enhancement (PRE) peak. The results showed that the pumping action of particle precipitation into the auroral zone has moderately modified the equatorial F2 peak height. However, F2 peak height seems to be more sensitive to HILDCAA effects during PRE time, showing the highest variations and sinusoidal oscillations in the cross-correlation indices.

scholarly journals Pre-storm <I>Nm</I>F2 enhancements at middle latitudes: delusion or reality?

2009 ◽  
Vol 27 (3) ◽  
pp. 1321-1330 ◽  
Author(s):  
A. V. Mikhailov ◽  
L. Perrone
Keyword(s):  
Magnetic Storm ◽  
Electric Fields ◽  
Geomagnetic Activity ◽  
Critical Analysis ◽  
Geomagnetic Storms ◽  
Activity Level ◽  
Quiet Time ◽  
Auroral Activity ◽  
Middle Latitudes ◽  
Plasma Ring

Abstract. A critical analysis of recent publications devoted to the NmF2 pre-storm enhancements is performed. There are no convincing arguments that the observed cases of NmF2 enhancements at middle and sub-auroral latitudes bear a relation to the following magnetic storms. In all cases considered the NmF2 pre-storm enhancements were due to previous geomagnetic storms, moderate auroral activity or they presented the class of positive quiet time events (Q-disturbances). Therefore, it is possible to conclude that there is no such an effect as the pre-storm NmF2 enhancement as a phenomenon inalienably related to the following magnetic storm. The observed nighttime NmF2 enhancements at sub-auroral latitudes may result from plasma transfer from the plasma ring area by meridional thermospheric wind. Enhanced plasmaspheric fluxes into the nighttime F2-region resulted from westward substorm-associated electric fields is another possible source of nighttime NmF2 enhancements. Daytime positive Q-disturbances occurring under very low geomagnetic activity level may be related to the dayside cusp activity.

scholarly journals Unexpected Southern Hemisphere ionospheric response to geomagnetic storm of 15 August 2015

2018 ◽  
Vol 36 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Ilya Edemskiy ◽  
Jan Lastovicka ◽  
Dalia Buresova ◽  
John Bosco Habarulema ◽  
Ivan Nepomnyashchikh
Keyword(s):  
South Africa ◽  
Southern Hemisphere ◽  
Geomagnetic Storms ◽  
Geomagnetic Latitude ◽  
Electron Content ◽  
Solar Activity Minimum ◽  
Total Electron ◽  
Ionospheric Response ◽  
Middle Latitudes ◽  
Local Noon

Abstract. Geomagnetic storms are the most pronounced phenomenon of space weather. When studying ionospheric response to a storm of 15 August 2015, an unexpected phenomenon was observed at higher middle latitudes of the Southern Hemisphere. This phenomenon was a localized total electron content (TEC) enhancement (LTE) in the form of two separated plumes, which peaked southward of South Africa. The plumes were first observed at 05:00 UT near the southwestern coast of Australia. The southern plume was associated with local time slightly after noontime (1–2 h after local noon). The plumes moved with the Sun. They peaked near 13:00 UT southward of South Africa. The southern plume kept constant geomagnetic latitude (63–64° S); it persisted for about 10 h, whereas the northern plume persisted for about 2 h more. Both plumes disappeared over the South Atlantic Ocean. No similar LTE event was observed during the prolonged solar activity minimum period of 2006–2009. In 2012–2016 we detected altogether 26 LTEs and all of them were associated with the southward excursion of Bz. The negative Bz excursion is a necessary but not sufficient condition for the LTE occurrence as during some geomagnetic storms associated with negative Bz excursions the LTE events did not appear.

An opposite response of the low-latitude ionosphere at Asian and American sectors during storm recovery phase: drivers from below and above

2020 ◽  
Author(s):  
Chao Xiong ◽  
Hermann Luehr ◽  
Yosuke Yamazaki
Keyword(s):  
Geomagnetic Storms ◽  
Recovery Phase ◽  
The Philippines ◽  
Lower Atmosphere ◽  
Electron Content ◽  
Early Recovery ◽  
Total Electron ◽  
Ionospheric Response ◽  
Swarm Satellites ◽  
Opposite Response

&lt;p&gt;The energy input from the solar wind and magnetosphere is thought to dominate the ionospheric response during geomagnetic storms. However, at the storm recovery phase, the role of forces from lower atmosphere could be as important as that from above. In this study, we focused on the geomagnetic storm happened on 6&amp;#8211;11 September 2017. The ground-based total electron content (TEC) data as well as the F region in situ electron density measured by the Swarm satellites reveals that at low and equatorial latitudes the dayside ionosphere shows as prominent positive and negative responses at the Asian and American longitudinal sectors, respectively. The global distribution of thermospheric O/N2 ratio measured by global ultraviolet imager on board the TIMED satellite cannot well explain such longitudinally opposite response of the ionosphere. Comparison between the equatorial electrojet variations from stations at Huancayo in Peru and Davao in the Philippines suggests that the longitudinally opposite ionospheric response should be closely associated with the interplay of E region electrodynamics. By further applying nonmigrating tidal analysis to the ground&amp;#8208;based TEC data, we find that the diurnal tidal components, D0 and DW2, as well as the semidiurnal component SW1, are clearly enhanced over prestorm days and persist into the early recovery phase, indicating the possibility of lower atmospheric forcing contributing to the longitudinally opposite response of the ionosphere on 9&amp;#8211;11 September 2017.&lt;/p&gt;

Theoretically modeling the low-latitude, ionospheric response to large geomagnetic storms

Radio Science ◽  
2006 ◽  
Vol 41 (5) ◽  
Author(s):  
D. Anderson ◽  
A. Anghel ◽  
E. Araujo ◽  
V. Eccles ◽  
C. Valladares ◽  
...  
Keyword(s):  
Geomagnetic Storms ◽  
Low Latitude ◽  
Ionospheric Response
Sign in / Sign up

Export Citation Format

Share Document