Biblio

Found 5 results
Filters: Author is Tsyganenko, N. A.  [Clear All Filters]
2019
Authors: Stephens G. K., Sitnov M I, Korth H., Tsyganenko N A, Ohtani S, et al.
Title: Global Empirical Picture of Magnetospheric Substorms Inferred From Multimission Magnetometer Data
Abstract: Magnetospheric substorms represent key explosive processes in the interaction of the Earth's magnetosphere with the solar wind, and their understanding and modeling are critical for space weather forecasting. During substorms, the magnetic field on the nightside is first stretched in the antisunward direction and then it rapidly contracts earthward bringing hot plasmas from the distant space regions into the inner magnetosphere, where they contribute to geomagnetic storms and Joule dissipation in the polar ionosphere, causing impressive splashes of aurora. Here we show for the first time that mining millions of spaceborne magnetometer data records from multiple missions allows one to reconstruct the global 3‐D picture of these stretching and dipolarization processes. Stretching results i. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025843 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025843
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2017
Authors: Andreeva V. A., and Tsyganenko N A
Title: Empirical modeling of the quiet and storm-time geosynchronous magnetic field
Abstract: A dynamical empirical model of the near-geosynchronous magnetic field has been constructed, based on a recently developed RBF approach and a multi-year set of spacecraft data taken by THEMIS, Polar, Cluster, and Van Allen Probes missions including 133 geomagnetic storms in the time interval between 1996 and 2016. The model describes the field as a function of Cartesian solar-magnetic coordinates, dipole tilt angle, solar wind ram pressure, and of a set of dynamic variables representing the response of the magnetosphere to the external driving/loading during the active phase of a space weather event, followed by the internal relaxation/dissipation during the storm recovery. In terms of the disturbance level, the model's validity range extends to intense storms with peak Sym-H values down to. . .
Date: 12/2017 Publisher: Space Weather DOI: 10.1002/2017SW001684 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017SW001684/full
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2015
Authors: Stephens G. K., Sitnov M I, Ukhorskiy A Y, Roelof E. C., Tsyganenko N A, et al.
Title: Empirical modeling of the storm-time innermost magnetosphere using Van Allen Probes and THEMIS data: Eastward and banana currents
Abstract: The structure of storm-time currents in the inner magnetosphere, including its innermost region inside 4RE, is studied for the first time using a modification of the empirical geomagnetic field model TS07D and new data from Van Allen Probes and THEMIS missions. It is shown that the model, which uses basis-function expansions instead of ad hoc current modules to approximate the magnetic field, consistently improves its resolution and magnetic field reconstruction with the increase of the number of basis functions and resolves the spatial structure and evolution of the innermost eastward current. This includes a connection between the westward ring current flowing largely at inline image and the eastward ring current concentrated at inline image resulting in a vortex current pattern. A simil. . .
Date: 01/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/2015JA021700 Available at: http://doi.wiley.com/10.1002/2015JA021700
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2014
Authors: Sergeev V. A., Nikolaev A. V., Tsyganenko N A, Angelopoulos V, Runov A. V., et al.
Title: Testing a two-loop pattern of the substorm current wedge (SCW2L)
Abstract: Recent quantitative testing of the classical (region 1 sense) substorm current wedge (SCI) model revealed systematic discrepancies between the observed and predicted amplitudes, which suggested us to include additional region 2 sense currents (R2 loop) earthward of the dipolarized region (SCW2L model). Here we discuss alternative circuit geometries of the 3-D substorm current system and interpret observations of the magnetic field dipolarizations made between 6.6RE and 11RE, to quantitatively investigate the SCW2L model parameters. During two cases of a dipole-like magnetotail configuration, the dipolarization/injection front fortuitously stopped at r ~ 9RE for the entire duration of ~ 30 min long SCW-related dipolarization within a unique, radially distributed multispacecraft constellat. . .
Date: 02/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 947 - 963 DOI: 10.1002/2013JA019629 Available at: http://doi.wiley.com/10.1002/2013JA019629
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2006
Authors: Ukhorskiy A Y, Anderson B J, Brandt P C, and Tsyganenko N A
Title: Storm time evolution of the outer radiation belt: Transport and losses
Abstract: During geomagnetic storms the magnetic field of the inner magnetosphere exhibits large-scale variations over timescales from minutes to days. Being mainly controlled by the magnetic field the motion of relativistic electrons of the outer radiation belt can be highly susceptible to its variations. This paper investigates evolution of the outer belt during the 7 September 2002 storm. Evolution of electron phase space density is calculated with the use of a test-particle simulation in storm time magnetic and electric fields. The results show that storm time intensification of the ring current produces a large impact on the belt. In contrast to the conventional Dst effect the dominant effects are nonadiabatic and lead to profound and irreversible transformations of the belt. The diamagnetic in. . .
Date: 11/2006 Publisher: Journal of Geophysical Research DOI: 10.1029/2006JA011690 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2006JA011690/abstract
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