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...

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Bibliographic Details
Published in:Journal of geophysical research. Space physics 2019-07, Vol.124 (7), p.5641-5662
Main Authors: Andreeva, V. A., Tsyganenko, N. A.
Format: Article
Language:English
Subjects:
Charged particles
Clouds
Corona
Coronal mass ejection
Decay rate
Disturbances
Driving ability
Earth magnetosphere
Empirical models
Environmental impact
Geomagnetic disturbances
Geomagnetic storms
Geomagnetism
Gusts
Interplanetary medium
Ionosphere
Magnetic fields
Magnetic storms
magnetosphere
Magnetospheric magnetic field
Magnetospheric magnetic fields
Magnetospheric-solar wind relationships
modeling
Modelling
Parameterization
Ring currents
Rings (mathematics)
Shock waves
Solar corona
Solar wind
Space weather
Spacecraft
spacecraft data
Storms
Weather forecasting
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Summary: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‐driven storms, (2) CME‐driven storms preceded with a shock ahead of the CME, and (3) CME‐driven storms without such shocks. The storm time dynamics of the model current systems has been represented using the parametrization method developed by Tsyganenko and Sitnov (2005), based on dynamical variables Wi, calculated from concurrent solar wind characteristics and their previous history. The database included observations of THEMIS, Polar, Cluster, Geotail, and Van Allen Probes missions during 155 storms in 1997–2016. The model current systems drastically differ from each other with respect to decay rate and total current magnitudes. During SIR‐induced storms, all current systems saturate, while during CME‐induced disturbances, the saturation occurs only for the symmetric ring current and the tail current. The partial ring current parameters are drastically different between SIR‐ and CME‐induced storm sets. In the case of SIR‐driven storms, the total partial ring current is comparable with symmetric ring current, whereas for all CME‐induced events it is nearly twice higher. The results are compared with GOES 15 magnetometer observations. Plain Language Summary There exist several different types of disturbed solar wind that hits the Earth's magnetosphere and results in geomagnetic storms. In some cases, the solar wind gusts are caused by long‐lived high‐speed streams from magnetic holes in the Sun's corona, which overtake and compress the quiet flow ahead of them; these are termed “stream interaction regions.” Another largely different type of the solar wind disturbance is called “coronal mass ejections” (CMEs); they form as a result of a sudden eruption of dense clouds of the solar material. The CMEs arrive at the Earth's orbit with or without shock wave. It is well known that stream interaction region and CME result in a different magnetosphere and ionosphere response, but it was not yet taken into account in the data‐based models of the mag
ISSN:2169-9380
2169-9402
DOI:10.1029/2018JA026008