scholarly journals Simulation of off-equatorial ring current ion spectra measured by Polar for a moderate storm at solar minimum

1999 ◽  
Vol 104 (A1) ◽  
pp. 429-436 ◽  
Author(s):  
V. K. Jordanova ◽  
C. J. Farrugia ◽  
J. M. Quinn ◽  
R. B. Torbert ◽  
J. E. Borovsky ◽  
...  
Keyword(s):  
Solar Minimum ◽  
Ring Current ◽  
Moderate Storm

scholarly journals Distortions of the magnetic field by storm-time current systems in Earth's magnetosphere

2010 ◽  
Vol 28 (1) ◽  
pp. 123-140 ◽  
Author(s):  
N. Yu. Ganushkina ◽  
M. W. Liemohn ◽  
M. V. Kubyshkina ◽  
R. Ilie ◽  
H. J. Singer
Keyword(s):  
Magnetic Field ◽  
Ring Current ◽  
Geostationary Orbit ◽  
Modeling Framework ◽  
Inner Magnetosphere ◽  
Tail Current ◽  
Modeling Approaches ◽  
Intense Storm ◽  
The Magnetic Field ◽  
Moderate Storm

Abstract. Magnetic field and current system changes in Earth's inner magnetosphere during storm times are studied using two principally different modeling approaches: on one hand, the event-oriented empirical magnetic field model, and, on the other, the Space Weather Modeling Framework (SWMF) built around a global MHD simulation. Two storm events, one moderate storm on 6–7 November 1997 with Dst minimum about −120 nT and one intense storm on 21–23 October 1999 with Dst minimum about −250 nT were modeled. Both modeling approaches predicted a large ring current (first partial, later symmetric) contribution to the magnetic field perturbation for the intense storm. For the moderate storm, the tail current plays a dominant role in the event-oriented model results, while the SWMF results showed no strong tail current in the main phase, which resulted in a poorly timed storm peak relative to the observations. These results imply that the the development of a ring current depends on a strong force to inject the particles deep into the inner magnetosphere, and that the tail current is an important external source for the distortions of the inner magnetospheric magnetic field for both storms. Neither modeling approach was able to reproduce all the variations in the Bx and By components observed at geostationary orbit by GOES satellites during these two storms: the magnetopause current intensifications are inadequate, and the field-aligned currents are not sufficiently represented. While the event-oriented model reproduces rather well the Bz component at geostationary orbit, including the substorm-associated changes, the SWMF field is too dipolar at these locations. The empirical model is a useful tool for validation of the first-principle based models such as the SWMF.

scholarly journals Ring current ion composition during solar minimum and rising solar activity: Polar/CAMMICE/MICS results

2001 ◽  
Vol 106 (A9) ◽  
pp. 19131-19147 ◽  
Author(s):  
T. I. Pulkkinen ◽  
N. Yu. Ganushkina ◽  
D. N. Baker ◽  
N. E. Turner ◽  
J. F. Fennell ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Minimum ◽  
Ring Current ◽  
Ion Composition

scholarly journals Understanding storm-time ring current development through data-model comparisons of a moderate storm

2007 ◽  
Vol 112 (A4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jichun Zhang ◽  
Michael W. Liemohn ◽  
Darren L. De Zeeuw ◽  
Joseph E. Borovsky ◽  
Aaron J. Ridley ◽  
...  
Keyword(s):  
Data Model ◽  
Ring Current ◽  
Current Development ◽  
Model Comparisons ◽  
Moderate Storm

scholarly journals Relationships between the AE, ap and Dst indices near solar minimum (1974) and at solar maximum (1979)

1997 ◽  
Vol 15 (10) ◽  
pp. 1265-1270 ◽  
Author(s):  
M. M. Fares Saba ◽  
W. D. Gonzalez ◽  
A. L. Clúa de Gonzalez
Keyword(s):  
Seasonal Variation ◽  
Solar Minimum ◽  
Ring Current ◽  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Correlation Coefficients ◽  
The Sun ◽  
Yearly Average ◽  
First Time ◽  
Activity Indices

Abstract. Three-hourly average values of the Dst, AE and ap geomagnetic activity indices have been studied for 1 year's duration near the solar minimum (1974) and also at the solar maximum (1979). In 1979 seven intense geomagnetic storms (Dst <–100 nT) occurred, whereas in 1974 only three were reported. This study reveals: (1) the yearly average of AE is greater in 1974 than in 1979, whereas the inverse seems to be true for the yearly average of Dst, when a higher number of intense storms is present. These averages indicate the kind of activity occurring on the sun as shown in earlier work. (2) The seasonal variation of Dst is higher than that of ap and is almost negligible in AE. (3) The correlation coefficient of ap × AE is in general the highest, as the magnetometers that monitor both indices are close, and is surpassed only by the ap × Dst correlation during geomagnetic storms, when the influence of the ring current is dominant. The correlation of ap × Dst also shows a seasonal variability. (4) For the first time a study of correlation between ap and a linear combination of AE and Dst has also been made. We found higher correlation coefficients in this case as compared to those between ap × Dst and ap × AE.

Ring current model of the naphthalene molecule

1997 ◽  
Vol 92 (3) ◽  
pp. 609-617 ◽  
Author(s):  
RICCARDO ZANASI ◽  
PAOLO LAZZERETTI
Keyword(s):  
Ring Current ◽  
Current Model ◽  
Naphthalene Molecule

Investigation of Ring Current/Storm Dynamics

1991 ◽  
Author(s):  
H. L. Collin ◽  
J. B. Cladis ◽  
J. M. Quinn
Keyword(s):  
Ring Current ◽  
Storm Dynamics

Survey of Ring Current Composition During Magnetic Storms

1998 ◽  
Author(s):  
M. Grande ◽  
C. H. Perry ◽  
A. Hall ◽  
J. Fennell ◽  
B. Wilken
Keyword(s):  
Ring Current ◽  
Magnetic Storms

scholarly journals Decay of the Dst field of geomagnetic disturbance after substorm onset and its implication to storm-substorm relation

1996 ◽  
Vol 14 (6) ◽  
pp. 608-618 ◽  
Author(s):  
T. Iyemori ◽  
D. R. K. Rao
Keyword(s):  
Ring Current ◽  
Geomagnetic Storms ◽  
Sharp Decrease ◽  
Geomagnetic Disturbance ◽  
Substorm Onset ◽  
Significant Development ◽  
H Index ◽  
Magnetospheric Tail ◽  
Storms And Substorms ◽  
Substorm Onsets

Abstract. In order to investigate the causal relationship between magnetic storms and substorms, variations of the mid-latitude geomagnetic indices, ASY (asymmetric part) and SYM (symmetric part), at substorm onsets are examined. Substorm onsets are defined by three different phenomena; (1) a rapid increase in the mid-latitude asymmetric-disturbance indices, ASY-D and ASY-H, with a shape of so-called `mid-latitude positive bay\\'; (2) a sharp decrease in the AL index; (3) an onset of Pi2 geomagnetic pulsation. The positive bays are selected using eye inspection and a pattern-matching technique. The 1-min-resolution SYM-H index, which is essentially the same as the hourly Dst index except in terms of the time resolution, does not show any statistically significant development after the onset of substorms; it tends to decay after the onset rather than to develop. It is suggested by a simple model calculation that the decay of the magnetospheric tail current after substorm onset is responsible for the decay of the Dst field. The relation between the IMF southward turning and the development of the Dst field is re-examined. The results support the idea that the geomagnetic storms and substorms are independent processes; that is, the ring-current development is not the result of the frequent occurrence of substorms, but that of enhanced convection caused by the large southward IMF. A substorm is the process of energy dissipation in the magnetosphere, and its contribution to the storm-time ring-current formation seems to be negligible. The decay of the Dst field after a substorm onset is explained by a magnetospheric energy theorem.

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