Two‐step development of geomagnetic storms

Kamide, Y.; Yokoyama, Noboru; González, W. D.; Tsurutani, B. T.; Daglis, Ioannis A.; Brekke, A.; Masuda, S.

doi:10.1029/97ja03337

Cited by 256 publications

(231 citation statements)

References 22 publications

(12 reference statements)

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“…Of the eight storm events, seven are single-dip storms, meaning that there is only one significant perturbation minimum. June 1991 is the notable exception, with three separate Dst * minima (Figure 1), and is a more general case of the two-stage magnetic storm development described in Kamide et al (1998a). This preconditioning of the ring current development for this storm was discussed by Kozyra et al (2002), finding that the strong convection of each new stage cleared out most of the ions from the previous injections.…”

Section: Eight Magnetic Stormsmentioning

confidence: 99%

Ring Current Energy Input and Decay

Kozyra

Liemohn

2003

Space Science Reviews

118

104

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Abstract.A new view of the ring current as an active element in the geospace system has emerged in which the ring current responds not only to changing convection electric fields imposed by solar wind interactions but to internal dynamics of the magnetosphere-ionosphere-atmosphere (geospace) system. Variations in the plasma sheet density, temperature and composition, saturation of the polar cap potential drop (and presumably the cross-tail potential drop), modifications to the imposed convection potential in the inner magnetosphere due to ring current shielding effects, the presence of a pre-existing ring current population, storm-substorm coupling, and strong convection with and without accompanying substorm activity all have an impact on the ring current strength, formation and loss. All of these internal processes imply that the geoeffectiveness of a solar wind driver cannot be predicted on the basis of the characteristics of the driver alone but must reflect key aspects of the dynamically changing geospace environment, itself. This review gives a summary of new information on ring current input and decay processes focusing on implications for the global geospace response to solar wind drivers during magnetic storms and on open questions that can be addressed with new ENA imaging techniques.

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Section: Eight Magnetic Stormsmentioning

confidence: 99%

Ring Current Energy Input and Decay

Kozyra

Liemohn

2003

Space Science Reviews

118

104

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“…A weaker storm, with a smaller average convection electric field and a shorter main phase [e.g., Yokoyama andKamide, 1997], would be less likely to enhance the effect of a more intense storm that had preceded it. The quiet 3 hours between the two main phases in our double-dip storm corresponds to the minimum time interval between two peaks of IDstl imposed by Kamide et al [1998] in their statistical study of two-peaked Dst magnetic storms in order to exclude cases in which apparent decreases in Dst magnitude were caused by substorm effects (e.g., current wedge) and not definitively by the stormtime ring current. We choose the shortest allowable quiet interval (3 hours) between the two main phases in constructing our hypothetical double-dip storm so as to minimize the opportunity for charge exchange to deplete the seed …”

Section: Simulation Modelmentioning

confidence: 99%

“…Observational studies [e.g., Tsurutani et al, 1988; Yokoyama and Kamide, 1997; Kamide et al, 1998] show that especially intense magnetic storms (e.g., those during which Dst attains values < -toe nT) are often associated with two distinct intervals of large southward IMF Bz and with two distinct intervals of increasingly negative Dst indicating that a second ring-current enhance-fomia [e.g., Kamide et al, 1997], suggested that perhaps the ring current enhancement attained during the first stage of a double-dip storm provides a necessary seed population for the more intense ring current to be attained during the second enhancement. If so, then it seems that a double-dip storm would inherently attain a stronger ring current than a comparable single-dip storm.…”

Section: Introductionmentioning

confidence: 99%

Stormtime ring‐current formation: A comparison between single‐and double‐dip model storms with similar transport characteristics

Chen¹,

Lyons²,

Schulz³

2000

J. Geophys. Res.

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Abstract. Intense magnetic storms often develop in two stages such that a second ring current enhancement begins before the first ring current enhancement has recovered to the prestorm level. Since Dst traces of such storms exhibit two dips, we refer to these as double-dip storms. Here we compare double-and single-dip storms with similar convective and diffusive transport characteristics for effectiveness at forming the proton ring current. Our model storms consist of superposition of almost randomly occurring impulses in the convection electric field. We have synthesized a hypothetical double-dip storm consisting of a moderate 6-hour storm, followed by a 3-hour quiet interval and then by a more intense 15-hour storm, for a total duration of 24 hours. For comparison, we consider a single-dip model storm with an unmodulated 24-hour main phase during which the root-mean-square enhancement of the cross-tail potential drop is made equal to the timeweighted rms enhancement for the double-dip model storm. This leads to comparable timeaveraged diffusion coefficients for our single-and double-dip model storms. The mean enhancement of the cross-tail potential drop of the two storms are also comparable. When the stormtime proton plasma sheet distribution, the source of ring current protons, is left unchanged from its quiet (prestorm) level, we find little difference in proton energy content per unit R (which is geocentric distance normalized by RE) between our double-and single-dip model storms. The protonenergy content of the magnetosphere is roughly increased by a factor of 2.5 by either model storm under this scenario, in which the overall amount of stormtime transport, whether convective or diffusive, is nearly the same for the double-and single-dip model storms. As in our earlier work, we require here an enhanced stormtime plasma sheet population (in addition to enhanced particle transport) in order to achieve (for example) the 20-fold increase in IDstl characteristic of a large storm. Only when we invoke a two-stage stormtime enhancement of the boundary (plasma sheet) phase space density in combination with the two-stage enhancement in particle transport, our double-dip model storm does show a much larger total energy content than our single-dip model storm with a one-stage enhancement of the boundary spectrum. This suggests that plasma sheet preconditioning may be important for the development of especially intense storms.

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“…Figure 13 shows the results of a superposed epoch analyses by Yokoyama and Kamide (1997) and Kamide et al (1998b), for an examination of single storms and double storms. The top panel gives the AL index for single and double storm events.…”

Section: Multiple Magnetic Stormsmentioning

confidence: 99%

“…Plotted are curves for the total energy density as well as for the energy density of the 4 main ion species (H + , O + , He ++ , He + ). Kamide et al (1998b) recently suggested that such two-phase storms actually are a superposition of two consecutive storms with two consecutive main phases (instead of one storm with a two-step main phase). Following the SSC at 0341 UT, on March 24, and during the first main phase of the storm, when Dst reaches -130 nT, we notice the O + curve gradually rising from the pre-storm level of ~15% to above 50%.…”

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confidence: 99%

Space Storms and Space Weather Hazards

Daglis¹

2001

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Subject Terms Report Classification unclassified Classification of this page unclassified Classification of Abstract unclassified Limitation of Abstract UU Number of Pages 486REPORT DOCUMENTATION PAGE Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, -to review recent spacecraft measurements that have provided new insight into the dynamics and effects of space storms; -to review space weather hazards associated with space storms and pertinent to the operation of technological systems in space and on ground;-to discuss and assess methods of space weather forecasting, as well as national and international initiatives towards an efficient development of space climatology.Space weather, the invisible but nevertheless effective result of solar activity and solar-terrestrial coupling, has affected the operations of communication systems since the appearance of telegraph in the 19th century, though as an unknown trouble factor. Nowadays, the effects of space weather affect in various ways all communication modes, from cable to wireless to space-based systems. Moreover, space weather hazards include malfunction or even permanent damage of power distribution grids and of telecommunication, navigation and surveillance satellites, disturbances of over-the-horizon (OTH) radar, HF, VHF and UHF communications, surveying and navigation systems that use Global Positioning System (GPS) satellites, surveillance (optical and radar), and satellite tracking. Space weather influences on the Earth's weather and climate is still a developing topic. Little is known concerning the biological effects of space weather, especially regarding astronauts.This Institute could not be timelier. Space Weather, which has been defined as "conditions on the sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-and ground-based technological systems and can endanger human life", encompasses a broad range of phenomena impacting both space science and technology. The effects of Space Weather, while present throughout the solar cycle, gain particular prominence around the peak of the 11-year sunspot activity; the maximum of cycle 23 occurred in summer 2000.The fact that this ASI on Space Weather was held in Europe is particularly appropriate. European countries host a considerable repository of knowledge and world-class facilities in this field. Nevertheless, while Space Weather activities in c...

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Two‐step development of geomagnetic storms

Cited by 256 publications

References 22 publications

Ring Current Energy Input and Decay

Ring Current Energy Input and Decay

Stormtime ring‐current formation: A comparison between single‐and double‐dip model storms with similar transport characteristics

Space Storms and Space Weather Hazards

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