Evidence for presence of a global quasi-resonant mode of oscillations during high-intensity long-duration continuous AE activity (HILDCAA) events

Rout, Diptiranjan; Singh, R. P.; Pandey, Kuldeep; Pant, Tarun Kumar; Stolle, Claudia; Chakrabarty, D.; Thampi, Smitha V.; Bag, Tikemani

doi:10.1186/s40623-022-01642-1

Cited by 7 publications

(6 citation statements)

References 59 publications

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“…Tsurutani et al (2004) concluded that they were not substorms, and suggested instead that intensifications of the westwards electrojet by prompt penetration of interplanetary electric fields could be the cause. Rout et al (2022) also concluded that HILDCAAs were not directly related to substorms but produced by the excitation of a global perturbation with a "quasi-resonant frequency" of order 1.5-2 hr. On the other hand, Kim et al (2008) found that energetic particle injections at geosynchronous orbit during HILDCAAs were well-aligned with substorm onsets seen in global auroral imagery, so deduced that most of these activations were indeed substorms.…”

Section: Discussionmentioning

confidence: 99%

“…The IMF within the HSSs undergoes Alfvénic fluctuations on a variety of timescales ranging from minutes to hours (e.g., Rout et al., 2022). The superposition of long and short timescales results in variability within Φ D which differs for each HILDCAA event.…”

Section: Discussionmentioning

confidence: 99%

“…Rout et al. (2022) also concluded that HILDCAAs were not directly related to substorms but produced by the excitation of a global perturbation with a “quasi‐resonant frequency” of order 1.5–2 hr. On the other hand, Kim et al.…”

Section: Discussionmentioning

confidence: 99%

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Solar Wind‐Magnetosphere Coupling During High‐Intensity Long‐Duration Continuous AE Activity (HILDCAA)

Milan,

Mooney,

Bower

et al. 2023

JGR Space Physics

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High‐Intensity Long‐Duration Continuous AE Activity (HILDCAA) intervals are driven by High Speed solar wind Streams (HSSs) during which the rapidly‐varying interplanetary magnetic field (IMF) produces high but intermittent dayside reconnection rates. This results in several days of large, quasi‐periodic enhancements in the auroral electrojet (AE) index. There has been debate over whether the enhancements in AE are produced by substorms or whether HILDCAAs represent a distinct class of magnetospheric dynamics. We investigate 16 HILDCAA events using the expanding/contracting polar cap model as a framework to understand the magnetospheric dynamics occurring during HSSs. Each HILDCAA onset shows variations in open magnetic flux, dayside and nightside reconnection rates, the cross‐polar cap potential, and AL that are characteristic of substorms. The enhancements in AE are produced by activity in the pre‐midnight sector, which is the typical substorm onset region. The periodicities present in the intermittent IMF determine the exact nature of the activity, producing a range of behaviors from a sequence of isolated substorms, through substorms which merge into one‐another, to almost continuous geomagnetic activity. The magnitude of magnetic fluctuations, dB/dt, in the pre‐midnight sector during HSSs is sufficient to produce a significant risk of Geomagnetically Induced Currents.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Solar Wind‐Magnetosphere Coupling During High‐Intensity Long‐Duration Continuous AE Activity (HILDCAA)

Milan,

Mooney,

Bower

et al. 2023

JGR Space Physics

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“…In addition, they reported that the magnetotail responds to IMF fluctuations during HILDCAA. Rout et al (2022) used the wavelet transform and cross-spectrum analysis to examine the responses of two HILDCAA events to solar wind observation. It was found that the quasi-periodic oscillation of 1.5-2 hr in the interplanetary electric field is the most effective parameter that controls the solar wind-magnetosphere-Ionosphere coupling process during HILDCAA events.…”

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confidence: 99%

Dynamical Complexity Transitions During High‐Intensity Long Duration Continuous Auroral Activities (HILDCAA) Events: Feature Analysis Based on Neural Network Entropy

Oludehinwa,

Velichko,

Ogunsua

et al. 2023

Space Weather

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In this study, we examine the dynamical complexity transitions during HILDCAA events. HILDCAA preceded by an Interplanetary Coronal Mass Ejection (ICME) storm recovery phase, HILDCAA preceded by a Corotating Interaction Region (CIR) storm recovery phase, and non‐storm driven HILDCAA and geomagnetically quiet periods were investigated using the Auroral Electrojet index time series. Neural Network Entropy (NNetEn) was used to capture the dynamical complexity transitions during these sporadic events. The NNetEn was able to decipher the distinct dynamical features associated with the emergence of HILDCAA and the geomagnetically quiet periods. Our analysis revealed a high value of NNetEn during HILDCAA signifying that the complexity levels of the coupled solar wind‐magnetosphere‐ionosphere system for HILDCAA, driven by different interplanetary structures were high with no significance difference. Thus, indicating that during HILDCAA, the dynamical behavior of the underlying physical processes due to the energy deposition driven either by ICME, CIR or non‐storm HILDCAA remain the same. However, a deciphering feature of dynamical complexity between the geomagnetically quiet period and HILDCAA events was evident. It was noticed that as the HILDCAA emerges, the NNetEn depicts an increment in entropy value signifying that the complexity levels of the coupled solar wind‐magnetosphere‐ionosphere system increases, and as the dynamics transcend to its recovery state, a reduction in entropy was observed implying a decline in complexity levels. Low values of NNetEn revealing lower complexity levels are found to be associated with geomagnetically quiet periods.

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“…caused by PPEF, DDEF, disturbed thermospheric winds, and compositional changes in low to midlatitude regions during HILDCAA (daSilva et al, 2020;Koga et al, 2011;Matamba & Habarulema, 2021;Rout et al, 2022;Silva et al…”

mentioning

confidence: 99%

NO Radiative Cooling and Ionospheric Response to the HILDCAA Events Following Geomagnetic Storms

Ranjan,

Sunil Krishna,

Kumar

et al. 2023

JGR Space Physics

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Nitric oxide infrared (5.3 µm) radiative cooling plays an important role in Earth's upper atmospheric energy balance during space weather events. Its behavior during a HILDCAA event following a geomagnetic storm can be more complicated than what is observed in an isolated geomagnetic storm (without HILDCAA). In order to understand this contrast, two moderate (SYM‐Hmin −80 nT; April 2005 (event‐1) and −65 nT; December 2006 (event‐2)), and an intense (Dstmin −150 nT; May 2000 (event‐3)) geomagnetic storms followed by HILDCAA events are considered for this study. It is found that, despite the larger solar wind‐magnetospheric energy coupling during the main phases of event‐1 and event‐2, the NO radiative cooling (NORC) and energetic electron precipitation (EEP) rates are larger during the HILDCAA phase. TIE‐GCM simulations indicate that the NORC pattern can be mainly attributed to variation in temperature, [O], and [NO] during HILDCAA. A larger rates of EEP due to the continuous substorm activity contributed to an additional ionization in D‐region and E‐region of the northern polar ionosphere during HILDCAA period of event‐2. This work is the first attempt to understand the NORC and EEP fluctuations during HILDCAA events preceded by geomagnetic events like event‐1 and event‐2. This study presents a comprehensive investigation of NORC and energetic electron (>27.93 keV) precipitation rate during HILDCAA event preceded by a moderate geomagnetic storm. An atmospheric chemistry‐based NORC emission model is used to understand the variation of NORC during intense geomagnetic storm (event‐3).

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Evidence for presence of a global quasi-resonant mode of oscillations during high-intensity long-duration continuous AE activity (HILDCAA) events

Cited by 7 publications

References 59 publications

Solar Wind‐Magnetosphere Coupling During High‐Intensity Long‐Duration Continuous AE Activity (HILDCAA)

Solar Wind‐Magnetosphere Coupling During High‐Intensity Long‐Duration Continuous AE Activity (HILDCAA)

Dynamical Complexity Transitions During High‐Intensity Long Duration Continuous Auroral Activities (HILDCAA) Events: Feature Analysis Based on Neural Network Entropy

NO Radiative Cooling and Ionospheric Response to the HILDCAA Events Following Geomagnetic Storms

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