Hydromagnetic theory of geomagnetic storms

Dessler, A. J.; Parker, E. N.

doi:10.1029/jz064i012p02239

Cited by 768 publications

(491 citation statements)

References 22 publications

Supporting

Mentioning

477

Contrasting

Unclassified

Order By: Relevance

“…We estimate Dst from the calculated electron and proton energy content with the Dessler-Parker-Sckopke (DPS) relation [Dessler and Parker, 1959;Sckopke, 1966] and the sum of the estimated Dst is reasonable comparing with the observed Dst. Ring current electrons in this study may contribute 7.5% as much energy content as ring current protons over the L range.…”

Section: Discussionmentioning

confidence: 68%

Relative contribution of electrons to the stormtime total ring current energy content

Liu

Chen

Roeder

et al. 2005

Geophysical Research Letters

View full text Add to dashboard Cite

[1] We evaluate the relative importance of stormtime ring current electrons to protons by calculating the energy content ratio of electrons to protons for typical ring current energies inferred from observations and simulations. We analyze Explorer 45 measurements taken around the minimum Dst(=À171 nT) of the 17 December 1971 storm. We simulate the electron and proton ring current energy content during a hypothetical storm using drift-loss simulations. From the data analysis, we find that electrons with energies of $1 -50 keV and protons with energies of $10-200 keV contribute the most to the corresponding particle energy content. From both observations and simulations, the ring current electrons contribute only $1% as much energy content as ring current protons during quiet times. However, this ratio increases to $8-19% during storm main phase. Thus, the ring current electrons can contribute significantly to the ring current energy content during storms. Citation: Liu, S., M. W. Chen, J. L. Roeder, L. R. Lyons, and M. Schulz (2005), Relative contribution of electrons to the stormtime total ring current energy content, Geophys. Res. Lett., 32, L03110,

show abstract

Section: Discussionmentioning

confidence: 68%

Relative contribution of electrons to the stormtime total ring current energy content

Liu

Chen

Roeder

et al. 2005

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Combining with the Dessler-Parker-Sckopke relationship [Dessler and Parker, 1959;Sckopke, 1966], we have…”

Section: Results From 20 Idealized Stormsmentioning

confidence: 99%

“…Geomagnetic storms are identified using the Dst or SYM-H indices, whose depression is mainly attributed to the enhanced ring current in the inner magnetosphere [Dessler and Parker, 1959;Frank, 1967]. The major source of the ring current is regarded as the plasma transported from the main plasma sheet.…”

Section: Introductionmentioning

confidence: 99%

On the contribution of plasma sheet bubbles to the storm time ring current

et al. 2015

View full text Add to dashboard Cite

Particle injections occur frequently inside 10 Re during geomagnetic storms. They are commonly associated with bursty bulk flows or plasma sheet bubbles transported from the tail to the inner magnetosphere. Although observations and theoretical arguments have suggested that they may have an important role in storm time dynamics, this assertion has not been addressed quantitatively. In this paper, we investigate which process is dominant for the storm time ring current buildup: large‐scale enhanced convection or localized bubble injections. We use the Rice Convection Model‐Equilibrium (RCM‐E) to model a series of idealized storm main phases. The boundary conditions at 14–15 Re on the nightside are adjusted to randomly inject bubbles to a degree roughly consistent with observed statistical properties. A test particle tracing technique is then used to identify the source of the ring current plasma. We find that the contribution of plasma sheet bubbles to the ring current energy increases from ~20% for weak storms to ~50% for moderate storms and levels off at ~61% for intense storms, while the contribution of trapped particles decreases from ~60% for weak storms to ~30% for moderate and ~21% for intense storms. The contribution of nonbubble plasma sheet flux tubes remains ~20% on average regardless of the storm intensity. Consistent with previous RCM and RCM‐E simulations, our results show that the mechanisms for plasma sheet bubbles enhancing the ring current energy are (1) the deep penetration of bubbles and (2) the bulk plasma pushed ahead of bubbles. Both the bubbles and the plasma pushed ahead typically contain larger distribution functions than those in the inner magnetosphere at quiet times. An integrated effect of those individual bubble injections is the gradual enhancement of the storm time ring current. We also make two predictions testable against observations. First, fluctuations over a time scale of 5–20 min in the plasma distributions and electric field can be seen in the central ring current region for the storm main phase. We find that the plasma pressure and the electric field EY there vary over about 10%–30% and 50%–300% of the background values, respectively. Second, the maximum plasma pressure and magnetic field depression in the central ring current region during the main phase are well correlated with the Dst index.

show abstract

“…The modern concept of a radiation belt of bouncing and drifting protons and electrons trapped within the magnetosphere and producing the ring current was proposed by Singer (1957) and confirmed with the discovery of the radiation belts by both US and Soviet teams in 1959 (Van Allen and Frank, 1959b;Van Allen et al, 1959a;Vernov et al, 1969). Shortly thereafter Dessler and Parker (1959) and Sckopke (1966) showed that the magnetic field depression at the center of the Earth was proportional to the energy content of the particles trapped in the magnetic field. The depression on the surface of the Earth, the equatorial average value of which we term the D st index, is additionally enhanced by currents within the Earth that exclude the field of the newly-formed ring current from the Earth's interior.…”

Section: Introductionmentioning

confidence: 89%

Morphology of the ring current derived from magnetic field observations

2004

View full text Add to dashboard Cite

Abstract. Our examination of the 20 years of magnetospheric magnetic field data from ISEE, AMPTE/CCE and Polar missions has allowed us to quantify how the ring current flows and closes in the magnetosphere at a variety of disturbance levels. Using intercalibrated magnetic field data from the three spacecraft, we are able to construct the statistical magnetic field maps and derive 3-dimensional current density by the simple device of taking the curl of the statistically determined magnetic field. The results show that there are two ring currents, an inner one that flows eastward at ∼3 R E and a main westward ring current at ∼4-7 R E for all levels of geomagnetic disturbances. In general, the insitu observations show that the ring current varies as the D st index decreases, as we would expect it to change. An unexpected result is how asymmetric it is in local time. Some current clearly circles the magnetosphere but much of the energetic plasma stays in the night hemisphere. These energetic particles appear not to be able to readily convect into the dayside magnetosphere. During quiet times, the symmetric and partial ring currents are similar in strength (∼0.5 MA) and the peak of the westward ring current is close to local midnight. It is the partial ring current that exhibits most drastic intensification as the level of disturbances increases. Under the condition of moderate magnetic storms, the total partial ring current reaches ∼3 MA, whereas the total symmetric ring current is ∼1 MA. Thus, the partial ring current contributes dominantly to the decrease in the D st index. As the ring current strengthens the peak of the partial ring current shifts duskward to the pre-midnight sector. The partial ring current is closed by a meridional current system through the ionosphere, mainly the field-aligned current, which maximizes at local times near the dawn and dusk. The closure currents flow in the sense of region-2 field-aligned currents, downward into the ionosphere near the dusk and upward out of the ionosphere near the dawn.

show abstract

Hydromagnetic theory of geomagnetic storms

Cited by 768 publications

References 22 publications

Relative contribution of electrons to the stormtime total ring current energy content

Relative contribution of electrons to the stormtime total ring current energy content

On the contribution of plasma sheet bubbles to the storm time ring current

Morphology of the ring current derived from magnetic field observations

Contact Info

Product

Resources

About