Geomagnetic disturbances on ground associated with particle precipitation during SC

Safargaleev, V. V.; Kozlovsky, Alexander; Honary, F.; Voronin, A.; Turunen, T.

doi:10.5194/angeo-28-247-2010

Cited by 11 publications

(11 citation statements)

References 36 publications

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“…The time interval between the moment when the z-component of the IMF turned from north to south and the moment when the SYM-H index began to decrease continuously was 21 min, indicating that the response time of the SYM-H index to the southward component of the IMF was 21 min, which was consistent with the result that the lag time varied from 17 to 25 min for 5 cases with northward-to-southward turnings in the article by Hairston and Heelis [45]. The response of the magnetosphere to the disturbance caused by the solar wind is very complicated (e.g., [42,[46][47][48][49][50] and the references therein). Many more studies should be conducted to understand the time lag between the disturbance caused by the solar wind and the magnetosphere better.…”

Section: Discussionsupporting

confidence: 82%

Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999

Zhao

2022

Universe

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We use the SYM-H index to indicate the ring current index. We find that there were two periods during which the SYM-H index decreased quickly during the main phase of the geomagnetic storm on 21–22 October 1999. The first period from 11:44 p.m. UT on 21 October 1999 to 1:35 a.m. UT on 22 October 1999 is defined as step 1. Another period from 3:36 a.m. UT to 5:49 a.m. UT on 22 October 1999 is defined as step 3. The durations of step 1 and step 3 are defined as Δt1 and Δt3, respectively. The variation of the pressure-corrected SYM-H index during step 1 and step 3 are defined as ΔSYMHob1* and ΔSYMHob3*, respectively. The interplanetary (IP) sources responsible for ΔSYMHob1* and ΔSYMHob3* are determined as the solar wind during period 1 and period 3, respectively. We find that the largest southward component of the interplanetary magnetic field (Bsmax) during period 3 was larger than that during period 1, and the largest solar wind dawn-to-dusk electric field (Eymax) during period 3 was also larger than that during period 1. We also find that the time integral of Ey during period 3 was much larger than that during period 1. However, we find that |ΔSYMHob1*| was larger than |ΔSYMHob3*|, and |ΔSYMHob1*/Δt1| was larger than |ΔSYMHob3*/Δt3|, indicating that the geomagnetic activity intensity during a period does not depend on Bsmax or Eymax, nor does it depend on the time integral of Ey. What is the reason for this? We find that the solar wind dynamic pressure during period 1 was larger than that during period 3, indicating that the geomagnetic storm intensity during a period not only depends on the solar wind speed and Bs, but it also depends on the solar wind dynamic pressure. The magnetosphere took 4 min to respond to the IP shock.When the z-component of the interplanetary magnetic field (IMF) turned from northward to southward, the response time of the SYM-H index to the southward component of the IMF was 21 min.

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Section: Discussionsupporting

confidence: 82%

Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999

Zhao

2022

Universe

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“…In Figure , variations of vertical velocity and reflectivity at 80–90 km and the geomagnetic field are plotted as functions of time. At the start of the geomagnetic disturbance, electron precipitation is largely enhanced, as observed by MEPED onboard POES as shown in Figure (e.g., Safargaleev et al, ). At the same time, vertical velocity 1′ peak and reflectivity a′ peak, as indicated in the top two panels, coincide with each other and match with the first pulses of geomagnetic fields of X = H cos ( D ; N‐S direction) and Y = H sin ( D ; E‐W direction), where H and D are the horizontal component and declination angle of the geomagnetic field, respectively.…”

Section: Relationship Between Pmse and Vertical Velocitymentioning

confidence: 76%

“…Electrons with energy ( ε ) higher than ~30 keV can reach effectively to altitudes of 80–90 km and those with ε >~100 keV to the lower altitudes (< 80 km). The large enhancements of cosmic noise absorption (due to an increase of D region electron density by energetic electron precipitation) have been reported in association with sudden storm commencement by Safargaleev et al (). Thus, the wave‐like structure above 90 km can be induced by the precipitation of energetic electrons modulated by whistler mode chorus waves which scatter electrons into the loss cone as they drift (Meredith et al, ).…”

Section: Reflectivity and Vertical Velocity Responses Under Geomagnetmentioning

confidence: 82%

EISCAT Observation of Wave‐Like Fluctuations in Vertical Velocity of Polar Mesospheric Summer Echoes Associated With a Geomagnetic Disturbance

Lee

Kim

et al. 2018

JGR Space Physics

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By analyzing a data set from the European Incoherent SCATter (EISCAT) Very High Frequency (VHF) radar at Tromsø, we find that both radar reflectivity and upward ion velocity in a polar mesospheric summer echo (PMSE) layer simultaneously increased at the commencement of a local geomagnetic disturbance, which occurred at midnight on 9 July 2013. The onset of the upward velocity was followed by periodic repetition of~5 min during the initial 30-min stage, and then at later stage the vertical velocity oscillated with~7-and~20-min periodicities at 85-to 90-km altitudes. The~5-min periodicity is close to the buoyancy period, and the~7-and~20 min periodicities are consistent with gravity waves, thus suggesting that gravity waves can be generated by the effects of the geomagnetic disturbance. On the other hand, the variation of PMSE intensity (85-90 km) was in phase with fluctuations of electron densities (90-110 km) with 12-and~13-min periodicities at the initial and later stages, respectively. The initial creation of PMSE can be attributed to both the sudden onset of particle precipitation and ice particles produced by adiabatic cooling during the rapid updraft, as detected by large upward velocity. Our periodogram analysis suggests that variations of PMSE intensity seem to follow the same periods with E region electron density, which is moduled by energetic electron precipitation, while vertical velocity oscillates at atmospheric gravity wave periods.

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“…3a and b are time-shifted by 1.3 min (one sampled unit) for better matching with the mushroom-like appearance. Such a phase difference is well explained by the time lag due to the different speeds of the VLF waves and the resonant energetic electrons propagating from their interaction region in the equatorial plane of the magnetosphere (Safargaleev et al, 2003(Safargaleev et al, , 2010.…”

Section: Observation Results and Its Discussionmentioning

confidence: 99%

Strange VLF bursts in northern Scandinavia: case study of the afternoon "mushroom-like" hiss on 8 December 2013

Manninen¹,

Клейменова

Kozlovsky³

et al. 2015

Ann. Geophys.

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Abstract. We investigate a non-typical very low frequency (VLF) 1-4 kHz hiss representing a sequence of separated noise bursts with a strange "mushroom-like" shape in the frequency-time domain, each one lasting several minutes. These strange afternoon VLF emissions were recorded at Kannuslehto (KAN, ϕ = 67.74 • N, λ = 26.27 • E; L ∼ 5.5) in northern Finland during the late recovery phase of the small magnetic storm on 8 December 2013. The left-hand (LH) polarized 2-3 kHz "mushroom caps" were clearly separated from the right-hand (RH) polarized "mushroom stems" at the frequency of about 1.8-1.9 kHz, which could match the lower ionosphere waveguide cutoff (the first transverse resonance of the Earth-ionosphere cavity). We hypothesize that this VLF burst sequence could be a result of the modulation of the VLF hiss electron-cyclotron instability from the strong Pc5 geomagnetic pulsations observed simultaneously at ground-based stations as well as in the inner magnetosphere by the Time History of Events and Macroscale Interactions during Substorms mission probe (THEMIS-E; ThE). This assumption is confirmed by a similar modulation of the intensity of the energetic (1-10 keV) electrons simultaneously observed by the same ThE spacecraft. In addition, the data of the European Incoherent Scatter Scientific Association (EISCAT) radar at Tromsø show a similar quasi-periodicity in the ratio of the Hall-to-Pedersen conductance, which may be used as a proxy for the energetic particle precipitation enhancement. Our findings suggest that this strange mushroom-like shape of the considered VLF hiss could be a combined mutual effect of the magnetospheric ULF-VLF (ultra low frequency-very low frequency) wave interaction and the ionosphere waveguide propagation.

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Geomagnetic disturbances on ground associated with particle precipitation during SC

Cited by 11 publications

References 36 publications

Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999

Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999

EISCAT Observation of Wave‐Like Fluctuations in Vertical Velocity of Polar Mesospheric Summer Echoes Associated With a Geomagnetic Disturbance

Strange VLF bursts in northern Scandinavia: case study of the afternoon "mushroom-like" hiss on 8 December 2013

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Geomagnetic disturbances on ground associated with particle precipitation during SC

Cited by 11 publications

References 36 publications

Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999

Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999

EISCAT Observation of Wave‐Like Fluctuations in Vertical Velocity of Polar Mesospheric Summer Echoes Associated With a Geomagnetic Disturbance

Strange VLF bursts in northern Scandinavia: case study of the afternoon &quot;mushroom-like&quot; hiss on 8 December 2013

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Strange VLF bursts in northern Scandinavia: case study of the afternoon "mushroom-like" hiss on 8 December 2013