Found 7 entries in the Bibliography.

Showing entries from 1 through 7


Empirical Modeling of the Geomagnetosphere for SIR and CME-Driven Magnetic Storms

During geomagnetic disturbances, the solar wind arrives in the form of characteristic sequences lasting from tens of hours to days. The most important magnetic storm drivers are the coronal mass ejections (CMEs) and the slow-fast stream interaction regions (SIRs). Previous data-based magnetic field models did not distinguish between these types of the solar wind driving. In the present work we retained the basic structure of the Tsyganenko and Andreeva (2015) model but fitted it to data samples corresponding to (1) SIR-drive ...

Andreeva, V.; Tsyganenko, N.;

YEAR: 2019     DOI: 10.1029/2018JA026008

Magnetic Storms; Magnetosphere; Modeling; Solar wind; spacecraft data; Van Allen Probes

Global Empirical Picture of Magnetospheric Substorms Inferred From Multimission Magnetometer Data

Magnetospheric substorms represent key explosive processes in the interaction of the Earth\textquoterights 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 iono ...

Stephens, G.; Sitnov, M.; Korth, H.; Tsyganenko, N.; Ohtani, S.; Gkioulidou, M.; . Y. Ukhorskiy, A;

YEAR: 2019     DOI: 10.1029/2018JA025843

Current sheet thinning; Data-mining; Magnetotail dipolarization; Storm-substorm relationship; substorm current wedge; substorms; Van Allen Probes


Empirical modeling of the quiet and storm-time geosynchronous magnetic field

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 th ...

Andreeva, V.; Tsyganenko, N.;

YEAR: 2017     DOI: 10.1002/2017SW001684

geomagnetic field; geostationary orbit; Modeling; spacecraft data; Van Allen Probes


Reconstructing the magnetosphere from data using radial basis functions

A new method is proposed to derive from data magnetospheric magnetic field configurations without any a priori assumptions on the geometry of electric currents. The approach utilizes large sets of archived satellite data and uses an advanced technique to represent the field as a sum of toroidal and poloidal parts, whose generating potentials Ψ1 and Ψ2 are expanded into series of radial basis functions (RBF) with their nodes regularly distributed over the 3D modeling domain. The method was tested by reconstructing the inner ...

Andreeva, Varvara; Tsyganenko, Nikolai;

YEAR: 2016     DOI: 10.1002/2015JA022242

current systems; magnetospheric modeling; polar cusps; Van Allen Probes


Empirical modeling of the storm-time innermost magnetosphere using Van Allen Probes and THEMIS data: Eastward and banana currents

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 ...

Stephens, G.; Sitnov, M.; . Y. Ukhorskiy, A; Roelof, E.; Tsyganenko, N.; Le, G.;

YEAR: 2015     DOI: 10.1002/2015JA021700

eastward current; empirical geomagnetic field; magnetic storm; ring current; Van Allen Probes


Testing a two-loop pattern of the substorm current wedge (SCW2L)

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 para ...

Sergeev, V.; Nikolaev, A.; Tsyganenko, N.; Angelopoulos, V.; Runov, A.; Singer, H.; Yang, J.;

YEAR: 2014     DOI: 10.1002/2013JA019629

injections; magnetotail; substorm current wedge; substorms


Storm time evolution of the outer radiation belt: Transport and losses

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. Th ...

. Y. Ukhorskiy, A; Anderson, B.; Brandt, P.; Tsyganenko, N.;

YEAR: 2006     DOI: 10.1029/2006JA011690

Magnetopause Losses