Cross-correlation and cross-wavelet analyses of the solar wind IMF Bz and auroral electrojet index AE coupling during HILDCAAs

Souza, A. M. de; Echer, E.; Bolzan, Maurı́cio José Alves; Hajra, Rajkumar

doi:10.5194/angeo-36-205-2018

Cited by 26 publications

(18 citation statements)

References 31 publications

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“…Hajra et al (2014) have shown the main process of solar wind energy dissipation in the magnetosphere during HILDCAA is by Joule heating in the auroral region, which is responsible for 67 % of the input energy. It was seen that the coupling between solar wind and the magnetosphere during these events occurs mainly in periods ≤ 8 h (Souza et al, 2018). Similar periods were observed in most energetic periods in the AE index and B z IMF component.…”

Section: Introductionsupporting

confidence: 70%

“…Non-stationary time series can be analyzed by wavelet transform (WT), a powerful mathematical tool that is able to show the temporal variability of the power spectral density (Morettin, 1992). Wavelet functions ψ (t) are generated by a simple function called wavelet mother, shown in Equation 1, which suffers expansion ψ (t) → ψ (2t) and translations ψ (t) → ψ (t + 1) in time, giving rise to those wavelet functions well known as wavelet daughters (Torrence and Compo, 1998).…”

Section: Methodsmentioning

confidence: 99%

“…The continuous wavelet functions allow the separation of phase and amplitude components associated with the signal; therefore they are generally used for analysis of time series. The most common continuous wavelet functions are the Mexican hat and the Morlet functions (Torrence and Compo, 1998;Addison, 2018). In this paper, both a discrete and a complex wavelet function were used, the Haar function in order to remove long-term trends in the data and the Morlet function for the periodicity identification.…”

Section: Methodsmentioning

confidence: 99%

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Wavelet analysis of the magnetotail response to solar wind fluctuations during HILDCAA events

Franco

Echer

Bolzan³

2019

Ann. Geophys.

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Abstract. In this work a study of the effects of the high-intensity long-duration continuous AE activity (HILDCAAs) events in the magnetotail was conducted. The aim of this study was to search the main frequencies during HILDCAAs in the Bx component of the geomagnetic field in the magnetotail, as well as the main frequencies, at which the magnetotail responds to the solar wind during these events. In order to conduct this analysis the wavelet transform was employed during nine HILDCAA events that coincided with Cluster spacecraft mission crossing through the tail of the magnetosphere from 2003 to 2007. The most energetic periods for each event were identified. It was found that 76 % of them have periods ≤4 h. With the aim to search the periods that have the highest correlation between the IMF Bz (OMNI) component and the Cluster Bx geomagnetic field component, the cross wavelet analysis technique was also used in this study. The majority of correlation periods between the Bz (IMF) and Bx component of the geomagnetic field observed also were ≤4 h, with 62.9 % of the periods. Thus the magnetotail responds stronger to IMF fluctuations during HILDCCAS at 2–4 h scales, which are typical substorm periods. The results obtained in this work show that these scales are the ones on which the coupling of energy is stronger, as well as the modulation of the magnetotail by the solar wind during HILDCAA events.

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Section: Introductionsupporting

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Wavelet analysis of the magnetotail response to solar wind fluctuations during HILDCAA events

Franco

Echer

Bolzan³

2019

Ann. Geophys.

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“…During all HILDCAA categories, the periodicities of the most energetic short-term power fluctuations are found to lie within the range of 0.5-3 hr. This lies within the range (<8 hr) where the solar-wind-magnetospheric coupling occurs during HILDCAA (de Souza et al, 2018). However, in majority of cases (~68% of 72 CIR HILDCAAs,~75% of 12 ICME HILCCAAs, and 56% of 29 nonstorm HILDCAAs), the most energetic periods are centered around 1.5-3 hr.…”

Section: 1029/2018sw001879mentioning

confidence: 75%

HILDCAA‐Related GIC and Possible Corrosion Hazard in Underground Pipelines: A Comparison Based on Wavelet Transform

et al. 2019

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High‐intensity long‐duration continuous auroral electrojet activities (HILDCAAs) are recognized as the continuous (duration >2 days) auroral electrojet activities (AE > 1,000 nT) caused by interplanetary Alfvén waves driving magnetic reconnection at the Earth's magnetopause. This paper focuses on the study of geoeffectiveness of HILDCAA on the basis of associated geomagnetically induced currents (GICs) and pipe‐to‐soil voltage (PSV) observed in an underground pipeline at Finnish Natural Gas Station, Mäntsälä. In this study, 113 HILDCAAs with different interplanetary sources (72 corotating interaction region‐storm preceded, 29 interplanetary coronal mass ejection‐storm preceded, and 12 nonstorm) have been selected and their possible contributions in underground pipeline corrosion have been quantitatively compared by assessing GIC/PSV profiles for each of these events. In addition, the spectral characteristics of GIC during these events have been studied using continuous wavelet transforms. The Morlet wavelet has been applied to 10‐s modeled GIC data corresponding to each event to explore the main band structures and the periodicities found in GIC spectrum. GIC/PSV modeling is based on plane wave method and distributed source transmission line analogy between pipelines and electric circuits. HILDCAAs are found to drive a small‐amplitude, but continuous, fluctuation in GIC throughout the event duration of several days. This makes the cumulative effect of HILDCAAs in pipeline corrosion noteworthy. The spectral analysis shows that GIC possesses both short‐term, as well as continuous, power distribution with different periodicities. CIR‐preceded HILDCAAs are found to be more geoeffective while taking associated GIC and PSV into account. Possible physical explanations supporting the results have been presented.

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“…The CIRs are characterized by compressed plasma and magnetic field regions. These are known to be geoeffective causing weak to moderate geomagnetic storms, and intense, long-duration auroral activities at the Earth (Tsurutani & Gonzalez 1987;Tsurutani et al 2006;Hajra et al 2013Hajra et al , 2014aHajra et al ,c,b, 2015aHajra et al ,b, 2017aSouza et al 2016Souza et al , 2018Mendes et al 2017;Guarnieri et al 2018;Hajra & Tsurutani 2018a). They result from magnetic reconnection (Dungey 1961) between the southward component of CIR magnetic fields and the Earth's dayside magnetopause fields.…”

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confidence: 99%

Cometary plasma response to interplanetary corotating interaction regions during 2016 June–September: a quantitative study by the Rosetta Plasma Consortium

Hajra

Henri

Myllys

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Four interplanetary corotating interaction regions (CIRs) were identified during 2016 June-September by the Rosetta Plasma Consortium (RPC) monitoring in situ the plasma environment of the comet 67P/Churyumov-Gerasimenko (67P) at heliocentric distances of ∼3-3.8 au. The CIRs, formed in the interface region between low-and high-speed solar wind streams with speeds of ∼320-400 km s −1 and ∼580-640 km s −1 , respectively, are characterized by relative increases in solar wind proton density by factors of ∼13-29, in proton temperature by ∼7-29, and in magnetic field by ∼1-4 with respect to the pre-CIR values. The CIR boundaries are well defined with interplanetary discontinuities. Out of 10 discontinuities, four are determined to be forward waves and five are reverse waves, propagating at ∼5-92 per cent of the magnetosonic speed at angles of ∼20 •-87 • relative to ambient magnetic field. Only one is identified to be a quasi-parallel forward shock with magnetosonic Mach number of ∼1.48 and shock normal angle of ∼41 •. The cometary ionosphere response was monitored by Rosetta from cometocentric distances of ∼4-30 km. A quiet time plasma density map was developed by considering dependences on cometary latitude, longitude, and cometocentric distance of Rosetta observations before and after each of the CIR intervals. The CIRs lead to plasma density enhancements of ∼500-1000 per cent with respect to the quiet time reference level. Ionospheric modelling shows that increased ionization rate due to enhanced ionizing (>12-200 eV) electron impact is the prime cause of the large cometary plasma density enhancements during the CIRs. Plausible origin mechanisms of the cometary ionizing electron enhancements are discussed.

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Cross-correlation and cross-wavelet analyses of the solar wind IMF B_z and auroral electrojet index AE coupling during HILDCAAs

Cited by 26 publications

References 31 publications

Wavelet analysis of the magnetotail response to solar wind fluctuations during HILDCAA events

Wavelet analysis of the magnetotail response to solar wind fluctuations during HILDCAA events

HILDCAA‐Related GIC and Possible Corrosion Hazard in Underground Pipelines: A Comparison Based on Wavelet Transform

Cometary plasma response to interplanetary corotating interaction regions during 2016 June–September: a quantitative study by the Rosetta Plasma Consortium

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