Magnetic field of the magnetospheric ring current and its dynamics during magnetic storms

Feldstein, Y. I.; Grafe, A.; Pisarsky, V.Yu.; Prigansova, A.; Sumaruk, P. V.

doi:10.1016/0021-9169(90)90086-3

Cited by 14 publications

(8 citation statements)

References 24 publications

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“…This explained in their model the typically observed short decay time (2–4 h) at the beginning of the storm recovery phase, when the solar wind electric field starts diminish, and the subsequent slower recovery with a significantly longer decay time (10–20 h). Also other studies have confirmed that the ring current decay time is not constant but depends on the storm (or storm driver) intensity [see, e.g., Gonzalez et al , 1989; Akasofu , 1981; Feldstein et al , 1990; MacMahon and Llop‐Romero , 2008]. Also the increase of the fraction of oxygen ions, with a relatively short life time, in the ring current during large storms can decrease the effective ring current decay time [ Daglis et al , 1999].…”

Section: Introductionmentioning

confidence: 98%

Modeling the contributions of ring, tail, and magnetopause currents to the corrected Dst index

2010

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[1] We present a new semiempirical model describing the contributions of the ring, tail, and magnetopause currents to the Dcx index. We use the isotropic boundary (IB) location of energetic particles measured by the NOAA/POES satellites, as a proxy for the tail current strength. Using local linear regression, we derive the model parameters and their functional dependencies on solar wind and interplanetary magnetic field parameters and on IB latitude. The model gives the ring, tail, and magnetopause current contributions for the whole time interval 1999-2007, performing roughly equally well during all activity levels. We find that the coefficient of proportionality between the square root of solar wind pressure and the magnetopause current contribution is larger than in earlier estimates. Ring current decay time is found to decrease with increasing solar wind electric field and dynamic pressure. We estimate the average quiet time level of the combined ring and tail (magnetopause) current contributions to Dcx to be roughly −7 nT (+13 nT). The average tail current contribution is found to be about 34% of the Dcx index, which is somewhat larger than previous estimates based on smaller-intensity storms. For individual storms the tail current contribution can reach up to −160 nT (about 40%-60% of the pressure corrected Dcx). The present model agrees well with earlier results for individual storms based on detailed dynamical models of the magnetosphere. Our work demonstrates that the different current contributions to Dcx during both active and quiet time intervals can be reliably estimated using solar wind observations and isotropic boundary location.Citation: Asikainen, T., V. Maliniemi, and K. Mursula (2010), Modeling the contributions of ring, tail, and magnetopause currents to the corrected Dst index,

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Section: Introductionmentioning

confidence: 98%

Modeling the contributions of ring, tail, and magnetopause currents to the corrected Dst index

2010

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“…One should note that the Dst index has contributions from other current systems such as the Chapman-Ferraro magnetopause current and the magnetotail current (Baumjohann, 1986;Gonzalez et al, 1994;Feldstein et al, 2003) as well. However the exact level of the various contributions is being debated (Feldstein et al, 1990(Feldstein et al, , 2003. The Dst index is derived from hourly averages of the horizontal component of the geomagnetic field, usually recorded at four or six low-latitude observatories.…”

Section: Introductionmentioning

confidence: 99%

Statistical studies of geomagnetic storms with peak Dst≤−50nT from 1957 to 2008

Echer

González

Tsurutani

2011

Journal of Atmospheric and Solar-Terrestrial Physics

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“…The D field, on the other hand, has a relevant role in generating magnetic noise interference in diver magnetic detections, as it consists of DSt (Storms) and Dloc (Local variations). DSt itself consists of DR (Ring currents) and DP1 (Auroral substorms) (Parkinson, 1983;Fairfield, 1990;Feldstein et al, 1990). The sum of all these field components (aperiodic) determines an irregular transient magnetic field of high energy.…”

Section: The Magnetic Environment In Harboursmentioning

confidence: 99%