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Daglis, Ioannis A.

doi:10.1023/a:1013873329054

Cited by 36 publications

(10 citation statements)

References 75 publications

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“…The Dst index time series is the longitudinal average of low-latitude, ground-level geomagnetic disturbance (Sugiura, 1964;World Data Center for Geomagnetism et al, 2015). It is useful for identifying the primary evolutionary phases of individual magnetic storms (e.g., Loewe & Prölss, 1997;McPherron) (e.g., Daglis, 2001) that is so distinctive it is sometimes taken to be the defining characteristic of a magnetic storm (e.g., Gonzalez et al, 1994).…”

Section: The Dst Time Seriesmentioning

confidence: 99%

Some Experiments in Extreme‐Value Statistical Modeling of Magnetic Superstorm Intensities

Love

2020

Space Weather

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In support of projects for forecasting and mitigating the deleterious effects of extreme space weather storms, an examination is made of the intensities of magnetic superstorms recorded in the Dst index time series . Modified peak-over-threshold and solar cycle, block-maximum samplings of the Dst time series are performed to obtain compilations of storm maximum −Dst m intensity values. Lognormal, upper limit lognormal, generalized Pareto, and generalized extreme-value model distributions are fitted to the −Dst m data using a maximum-likelihood algorithm. All four candidate models provide good representations of the data. Comparisons of the statistical significance and goodness of fits of the various models give no clear indication as to which model is best. The statistical models are used to extrapolate to extreme-value intensities, such as would be expected (on average) to occur once per century. An upper limit lognormal fit to peak-over-threshold −Dst m data above a superstorm threshold of 283 nT gives a 100-year extrapolated intensity of 542 nT and a 68% confidence interval (obtained by bootstrap resampling) of [466, 583] nT. A generalized extreme-value distribution fit to solar cycle, block-maximum −Dst BM m data gives a nine-solar cycle (approximately 100-year) extrapolated intensity of 591 nT. The Dst data are found to be insufficient for providing usefully accurate estimates of a statistically theoretical upper limit for magnetic storm intensity. Secular change in storm intensities is noted, as is a need for improved estimates of pre-1957 magnetic storm intensities.

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Section: The Dst Time Seriesmentioning

confidence: 99%

Some Experiments in Extreme‐Value Statistical Modeling of Magnetic Superstorm Intensities

Love

2020

Space Weather

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“…Radial flow and pressure profiles of ring current particles during quiet periods have a maximum at L max = 5.5-6.0, and during storms at L max = 2-5 (Kovtyukh and Panasyuk, 2008). In quiet times, the current mainly consists of protons (average partial concentration ∼ 90 %, Daglis et al, 1999). During the magnetic storms there is a sharp increase in the density of atomic oxygen ions O + originating from the ionosphere.…”

Section: The Earth's Ring Currentmentioning

confidence: 99%

“…During the magnetic storms there is a sharp increase in the density of atomic oxygen ions O + originating from the ionosphere. However, protons continue to make the main contribution to the ring current during typical storms, with an average partial energy density of ∼ 70 % (Daglis et al, 1999). During very large storms, the O + ion component becomes predominant (Daglis et al, 1999).…”

Section: The Earth's Ring Currentmentioning

confidence: 99%

“…The outflow of ions through the dayside magnetopause can be a significant term in the energy balance of the storm-time ring current during the main phase of the storm (Kozyra and Liemohn, 2003). Also, the initial fast stage of the recovery phase of very strong storms can be associated with the decay of the oxygen component, and the subsequent slow stage with the decay of the proton component (Daglis et al, 1999). Rapid decay of the inner part of the magnetospheric tail current (Alexeev et al, 1996) and the sudden change in the IMF direction to northward at the end of the main phase of the storm were also considered mechanisms which act during the fast phase of the recovery of powerful storms, which can lead to an inversion of the convection electric field and ejection of the ring current from the outer regions of the trapping region (Ebihara and Ejiri, 1998).…”

Section: The Earth's Ring Currentmentioning

confidence: 99%

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Influence of the Earth's ring current strength on Størmer's allowed and forbidden regions of charged particle motion

Lavrukhin¹,

Alexeev²,

Tyutin³

2019

Ann. Geophys.

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Abstract. Størmer's particles' trapping regions for a planet with an intrinsic dipolar magnetic field are considered, taking into account the ring current which arises due to the trapped particles' drift for the case of the Earth. The influence of the ring current on the particle trapping regions' topology is investigated. It is shown that a critical strength of the ring current exists under which further expansion of the trapping region is no longer possible. Before reaching this limit, the dipole field, although deformed, retains two separated Størmer regions. After transition of critical magnitude, the trapping region opens up, and charged particles, which form the ring current, get the opportunity to leave it, thus decreasing the ring current strength. Numerical calculations have been performed for protons with typical energies of the Earth's radiation belt and ring current. For the Earth's case, the Dst index for the critical ring current strength is calculated.

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“…In our problem we consider only symmetric ring current due to the axial symmetry. In addition to the large-scale potential electric fields, that appear in the nightside magnetosphere due to the prolonged southern IMF, the impulsive induced electric fields (which also can transport particles into the inner magnetosphere) can arise due to the magnetic field reconfigurations of during substorms (Daglis, 2001). These two particle's transport and acceleration mechanisms can act simultaneously Ebihara and Ejiri (2003).…”

Section: The Earth's Ring Currentmentioning

confidence: 99%

Influence of the Earth's ring current strength on the Størmer's allowed and forbidden regions of charged particles motion

Lavrukhin¹,

Alexeev²,

Tyutin³

2018

Preprint

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Abstract. Størmer's particles' trapping regions for a planet with an intrinsic dipolar magnetic field are considered, taking into account the ring current which arises due to the trapped particles drift for the case of Earth. The influence of the ring current on the particles' trapping regions topology is investigated. It is shown that a critical strength of the ring current exists, under which further expansion of the trapping region is no longer possible. Before reaching this limit, the dipole field, although deformed, retains two separated Størmer regions. After transition of critical magnitude, the trapping region opens up and charged particles, which form the ring current, get the opportunity to leave it (go to infinity or come to the trapping region from infinity), thus decreasing the ring current strength. Numerical calculations have been performed for protons with typical energies of Earth's radiation belt and ring current. For the Earth case, the Dst index for the critical ring current strength is calculated.

show abstract

Untitled

Cited by 36 publications

References 75 publications

Some Experiments in Extreme‐Value Statistical Modeling of Magnetic Superstorm Intensities

Some Experiments in Extreme‐Value Statistical Modeling of Magnetic Superstorm Intensities

Influence of the Earth's ring current strength on Størmer's allowed and forbidden regions of charged particle motion

Influence of the Earth's ring current strength on the Størmer's allowed and forbidden regions of charged particles motion

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