Effects of substorms on the stormtime ring current index &amp;lt;i&amp;gt;Dst&amp;lt;/i&amp;gt;

Rostoker, G.

doi:10.1007/s00585-000-1390-2

Cited by 15 publications

(2 citation statements)

References 14 publications

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“…[12] This result implies that surface charging by particles injected from geomagnetic tail may be the most probable cause of the severe anomalies. It is known that increase of Kp index is partly due to the collapse of stretched magnetic field lines on the night side of the Earth which also causes the injection of energetic particles from the region of geomagnetic tail [Rostoker, 2000]. In addition, during geomagnetic storms, magnetic field stretching makes nonuniform particle distribution at the geostationary orbit [Onsager et al, 2002;Lee et al, 2006].…”

Section: Local Time Dependencementioning

confidence: 99%

Analysis of GEO spacecraft anomalies: Space weather relationships

et al. 2011

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[1] The authors welcome the comment from J. E. Mazur and T. P. O'Brien [Mazur and O'Brien, 2012] on our recently published study [Choi et al., 2011]. In our paper, we investigated the geostationary Earth orbit (GEO) satellite anomalies archived by Satellite News Digest (SND) during 1997-2009 in order to search for possible influences of space weather on the anomaly occurrences. There were good relationships between geomagnetic activity (as measured by the Kp index) and anomaly occurrences of the GEO satellites; the satellite anomalies occurred mainly in the midnight-to-morning sector, and the anomalies were found more frequently in spring and fall than in summer and winter. A comparison of the SND data with data from Los Alamos National Laboratory satellites showed that low-energy (<100 keV) electrons exhibit behavior similar to that of spacecraft anomalies and implied that the spacecraft charging may be a primary contributor to the GEO spacecraft anomalies reported on the SND Web site (http://www.sat-index.co.uk). [2] Mazur and O'Brien [2012] point out that some anomalies used in our analysis were not obviously caused by space weather effects. In fact, we intentionally used all of the GEO satellite anomalies listed on the SND Web site in order to exclude a subjective selection effect. Our event list, chosen from the SND database, represented major satellite anomalies that had significant financial impacts. There were numerous minor satellite anomalies reported from many agencies, and we want to emphasize that their tendency was similar to that of our event list. While the number of events may not be large enough to analyze local time dependence, when the anomalies reported by SND from 2010 to 2011 (indicated in Figure 1 by star symbols) are included, it is very clear that the anomaly occurrences are more frequent at nighttime than during the daytime. [3] Mazur and O'Brien [2012] also mention the relationship between GEO satellite anomalies and charging effects. Internal charging may be concerned with high-energy electrons and independent of its local time, while external charging is related to low-energy electrons and dependent on its local time. As we noted in Choi et al. [2011], the flux of 100 keV electrons on GEO orbit shows nonuniform distribution on the local time, yet these electrons don't have enough energy to penetrate satellite walls and charge internal components. At this moment, we don't fully understand the mechanism by which charged particles bring about the anomalies. [4] We support the proposal made by Mazur and O'Brien [2012] that an agency be established to maintain adequate and open anomaly and abnormality lists containing all information about events. We also anticipate that our paper will serve as encouragement to all the agencies concerned to make their anomaly data publicly available and to investigate an occurrence mechanism of spacecraft anomaly. References

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Section: Local Time Dependencementioning

confidence: 99%

Analysis of GEO spacecraft anomalies: Space weather relationships

et al. 2011

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“…Therefore, ap should be sensibly more responsive to electric fields that contribute to ring current enhancement (that is, to Dst changes) inside geosynchronous orbit during strong disturbances than AE or AL, which are measured inside the auroral oval (Rostoker, 2000;Thomsen, 2004). In addition, Lockwood et al (2019a) have noticed that AE saturates at high geomagnetic activity measured by am (when am > 150, with am a mid-latitude index very similar to ap) probably because the auroral oval then expands equatorward of the stations used to measure AE.…”

Section: Physical Interpretation-insights From Entropy Analysismentioning

confidence: 99%

Dynamical Properties of Peak and Time‐Integrated Geomagnetic Events Inferred From Sample Entropy

2020

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We provide a comprehensive statistical analysis of the sample entropy of peak and time‐integrated geomagnetic events in 2001–2017, considering different measures of event strength, different geomagnetic indices, and a simplified solar wind‐magnetosphere coupling function P*. Our investigations reveal the existence of significant correlations between the entropies of Dst, ap, and P*, and between such entropies and event strengths, as well as good correlations between peak levels of solar wind‐magnetosphere coupling and ring current ( Dst) and ap entropies, suggesting a potential predictability of significant Dst and ap events on the basis of appropriate functions of P*. Sensibly weaker correlations are found with AE entropy. We further show the presence of several significant entropy correlations between geomagnetic indices, solar wind‐magnetosphere coupling, and trapped or precipitated energetic electron and ion fluxes measured by geostationary and low Earth orbit satellites in the outer radiation belt during the same periods. Entropy correlations between Dst and trapped or precipitated 30‐ to 80‐keV ion fluxes at low L and between AE and trapped 40‐keV electron fluxes at geostationary orbit correspond well with ring current properties and substorm‐induced injections, respectively. Entropy correlations between ap and precipitation rates of energetic ion and electron fluxes demonstrate the sensibility of ap index entropy to both low‐energy (5–30 keV) electron injections and ring current. The stronger entropy correlation between solar wind‐magnetosphere coupling and ap than AE likely stems from the more stochastic behavior of electron injections and fast losses near geostationary orbit.

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Testing for lack of dependence in the functional linear model

et al. 2008

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The authors consider the linear model Y, = *X, + E, relating a functional response with explanatory variables. They propose a simple test of the nullity of \k based on the principal component decomposition. The limiting distribution of their test statistic is chi-squared, but this distribution is also an excellent approximation in finite samples. The authors illustrate their method using data from terrestrial magnetic observatories.Un test d'absence de dependance dans un modele fonctionnel lineaire R 6 s u d : Les auteurs s'intkressent au modkle lintaire Y, = Q X , + E, liant une variable dponse fonctionnelle h des variables explicatives. 11s proposent un test simple de nullit6.de * fond6 sur la dkomposition en composantes principales. L a loi limite de leur statistique est une khi-deux, mais cette loi foumit aussi une excellente approximation h taille finie. Les auteurs illustrent leur m6thode au moyen de donnks provenant d'observatoires du champ magnttique terrestre.

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Effects of substorms on the stormtime ring current index <i>Dst</i>

Cited by 15 publications

References 14 publications

Analysis of GEO spacecraft anomalies: Space weather relationships

Analysis of GEO spacecraft anomalies: Space weather relationships

Dynamical Properties of Peak and Time‐Integrated Geomagnetic Events Inferred From Sample Entropy

Testing for lack of dependence in the functional linear model

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