Ring Current Energy Input and Decay

Kozyra, J. U.; Liemohn, Michael W.

doi:10.1023/b:spac.0000007516.10433.ad

Cited by 120 publications

(114 citation statements)

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“…By carefully inspecting such a profile, we note that the storm‐time increases start during the so‐called Storm Sudden Commencement (SSC), before the decrease of the Dst parameter. Anyway, it has been observed by Kozyra and Liemohn [2003] that the ring current generally starts growing before the decrease of Dst , since other current systems occurring at the beginning of the storm partially compensate the effect of the ring current on Dst .…”

Section: Discussionmentioning

confidence: 99%

Modeling the time‐evolving plasma in the inner magnetosphere: An empirical approach

Orsini¹

2004

J. Geophys. Res.

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[1] The global plasma distribution in the inner magnetosphere is directly related to the time-evolving magnetospheric and solar wind conditions. However, it is difficult to derive a realistic global picture of the inner magnetosphere from in situ spacecraft measurements. In this study we approach this intriguing task by analyzing the H + spectra from CRRES Magnetospheric Ion Composition Spectrometer (MICS) and Low-Energy Magnetospheric Ion Composition Sensor (LOMICS) experiments (L shell between 3 and 9 and energies between 4 and 400 keV) during a large period including storm times as well as quiet times and by best fitting these proton spectra with those obtained via the empirical model proposed by Milillo et al. [2001]. The procedure is performed by tuning a subset of the model parameters in order to reconstruct the trend of the experimental data at the given location. It is shown that the profile versus time of the selected model parameters (strictly linked to the plasma distribution characteristics) is well correlated to the geomagnetic indexes. In particular, the storm-time development of both the diffused population at high energies and the convected/injected particles in the range of tens of keVs are highlighted. Subsequently, the trend of the proton distributions on a global scale is reconstructed by means of the mentioned empirical model. Finally, the macroscopic features and their developments on a global scale are analyzed in terms of energy density, electric potential, and equatorial current density.

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Section: Discussionmentioning

confidence: 99%

Modeling the time‐evolving plasma in the inner magnetosphere: An empirical approach

Orsini¹

2004

J. Geophys. Res.

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“…The ring current has long been understood in terms of injection and decay of the trapped particles that carry it (Burton et al, 1975) and the injection is more efficient when the interplanetary magnetic field points southward (see, e.g., Shi et al, 2012). The response is complicated by the fact that the interplanetary electric field also influences the decay of the ring current and there are other, internal magnetospheric factors which influence both the injection and the decay (see reviews by Kozyra and Liemohn, 2003;Pulkkinen, 2007). Enhancements of the ring current cause negative depressions in the index but will also influence other geomagnetic indices.…”

Section: Dependencies Of the Various Indices On Interplanetary Paramementioning

confidence: 99%

Reconstruction and Prediction of Variations in the Open Solar Magnetic Flux and Interplanetary Conditions

Lockwood

2013

Living Rev. Solar Phys.

133

173

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Historic geomagnetic activity observations have been used to reveal centennial variations in the open solar flux and the near-Earth heliospheric conditions (the interplanetary magnetic field and the solar wind speed). The various methods are in very good agreement for the past 135 years when there were sufficient reliable magnetic observatories in operation to eliminate problems due to site-specific errors and calibration drifts. This review underlines the physical principles that allow these reconstructions to be made, as well as the details of the various algorithms employed and the results obtained. Discussion is included of: the importance of the averaging timescale; the key differences between "range" and "interdiurnal variability" geomagnetic data; the need to distinguish source field sector structure from heliosphericallyimposed field structure; the importance of ensuring that regressions used are statistically robust; and uncertainty analysis. The reconstructions are exceedingly useful as they provide calibration between the in-situ spacecraft measurements from the past five decades and the millennial records of heliospheric behaviour deduced from measured abundances of cosmogenic radionuclides found in terrestrial reservoirs. Continuity of open solar flux, using sunspot number to quantify the emergence rate, is the basis of a number of models that have been very successful in reproducing the variation derived from geomagnetic activity. These models allow us to extend the reconstructions back to before the development of the magnetometer and to cover the Maunder minimum. Allied to the radionuclide data, the models are revealing much about how the Sun and heliosphere behaved outside of grand solar maxima and are providing a means of predicting how solar activity is likely to evolve now that the recent grand maximum (that had prevailed throughout the space age) has come to an end.

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“…Anderson et al, 2001), the enhanced convection electric field can inject more ions into the ring current and inner magnetosphere (e.g. Daglis and Kozyra, 2002;Kozyra and Liemohn, 2003;Liemohn and Kozyra, 2003), forming a larger azimuthal pressure gradient. Stronger R2 FACs will be generated by the enhanced misalignment between the large azimuthal pressure gradient and the orientation of the magnetic field flux tube.…”

Section: Seasonal Variation Of Cpcpmentioning

confidence: 99%

The efficiency of mechanisms driving Subauroral Polarization Streams (SAPS)

Wang

Lühr

2011

Ann. Geophys.

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Abstract.We have investigated the seasonal and diurnal variation of SAPS (Subauroral Polarization Streams) occurrence based on 3663 SAPS events identified in DMSP ion drift observations in the Northern Hemisphere during July 2001 and June 2003. Their relationships with high latitude convection electric field, substorm, and ionospheric conductivity have been addressed. SAPS occurrences show a clear seasonal and diurnal variation with the occurrence rates varying by a factor of 5. It is found that the convection electric field might play a dominant role in association with SAPS occurrence. Peak convection electric fields mark the occurrence maximum of SAPS. Substorm might play a secondary role related to SAPS occurrence. It account for the secondary maximum in SAPS occurrence rate during December solstice. Our work demonstrates that the substorm induced electric field can develop SAPS during relatively low global convection. Somewhat low fluxtube-integrated conductivity is favorable for SAPS to develop. Another topic is the temporal relationship between SAPS and substorm phases. SAPS can occur at substorm onset, substorm expansion and recovery phases. Most probably SAPS tend to occur 60 min/45 min after substorm onset during quiet/more disturbed geomagnetic activity, respectively. This indicates that enhanced global convection helps SAPS to develop quicker during substorms. The peak plasma velocity of SAPS is increased on average only by 5-10 % by the substorm process.

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Ring Current Energy Input and Decay

Cited by 120 publications

References 103 publications

Modeling the time‐evolving plasma in the inner magnetosphere: An empirical approach

Modeling the time‐evolving plasma in the inner magnetosphere: An empirical approach

Reconstruction and Prediction of Variations in the Open Solar Magnetic Flux and Interplanetary Conditions

The efficiency of mechanisms driving Subauroral Polarization Streams (SAPS)

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