Energy coupling function and solar wind‐magnetosphere dynamo

Kan, J. R.; Lee, L. C.

doi:10.1029/gl006i007p00577

Cited by 476 publications

(489 citation statements)

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“…vB (related to the electric field in the current sheet), vB 2 (Poynting flux) determine the level of geomagnetic activity (Perreault and Akasofu, 1978). v 2 B 2 describes the energy coupling function for the magnetospheric substorm and the delivered power (see also Kan and Lee, 1979). One has to consider that magnetospheric current systems may respond differently to the HSS related and the CME-related solar wind disturbances (cf.…”

Section: Discussionmentioning

confidence: 99%

Real-Time Solar Wind Prediction Based on SDO/AIA Coronal Hole Data

et al. 2015

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We present an empirical model based on the visible area covered by coronal holes close to the central meridian in order to predict the solar wind speed at 1 AU with a lead time up to four days in advance with a 1-h time resolution. Linear prediction functions are used to relate coronal hole areas to solar wind speed. The function parameters are automatically adapted by using the information from the previous 3 Carrington Rotations. Thus the algorithm automatically reacts on the changes of the solar wind speed during different phases of the solar cycle. The adaptive algorithm has been applied to and tested on SDO/AIA-193Å observations and ACE measurements during the years 2011 − 2013, covering 41 Carrington Rotations. The solar wind speed arrival time is delayed and needs on average 4.02 ± 0.5 days to reach Earth. The algorithm produces good predictions for the 156 solar wind high speed streams peak amplitudes with correlation coefficients of cc ≈ 0.60. For 80% of the peaks, the predicted arrival matches within a time window of 0.5 days of the ACE in situ measurements. The same algorithm, using linear predictions, was also applied to predict the magnetic field strength from coronal hole areas but did not give reliable predictions (cc ≈ 0.2).

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Section: Discussionmentioning

confidence: 99%

Real-Time Solar Wind Prediction Based on SDO/AIA Coronal Hole Data

et al. 2015

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“…Of particular importance are the solar wind velocity and the direction and strength of the interplanetary magnetic field (IMF). These ingredients combine into the solar wind electric field, a prime parameter affecting the coupling at the dayside magnetosphere through magnetic reconnection, which may lead to geomagnetic storms during strong driving [e.g., Gonzalez and Mozer, 1974;Perreault and Akasofu, 1978;Kan and Lee, 1979]. Another important parameter in solar wind-magnetosphere interaction is the solar wind Alfvén Mach number M A : the ratio of the bulk solar wind to Alfvén speeds [Lavraud and Borovsky, 2008;Borovsky, 2008].…”

Section: Introductionmentioning

confidence: 99%

Asymmetry of magnetosheath flows and magnetopause shape during low Alfvén Mach number solar wind

et al. 2013

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[1] Previous works have emphasized the significant influence of the solar wind Alfvén Mach number (M A ) on magnetospheric dynamics. Here we report statistical, observational results that pertain to changes in the magnetosheath flow distribution and magnetopause shape as a function of solar wind M A and interplanetary magnetic field (IMF) clock angle orientation. We use all Cluster 1 data in the magnetosheath during the period 2001-2010, using an appropriate spatial superposition procedure, to produce magnetosheath flow distributions as a function of location in the magnetosheath relative to the IMF and other parameters. The results demonstrate that enhanced flows in the magnetosheath are expected at locations quasi-perpendicular to the IMF direction in the plane perpendicular to the Sun-Earth line; in other words, for the special case of a northward IMF, enhanced flows are observed on the dawn and dusk flanks of the magnetosphere, while much lower flows are observed above the poles. The largest flows are adjacent to the magnetopause. Using appropriate magnetopause crossing lists (for both high and low M A ), we also investigate the changes in magnetopause shape as a function of solar wind M A and IMF orientation. Comparing observed magnetopause crossings with predicted positions from an axisymmetric semi-empirical model, we statistically show that the magnetopause is generally circular during high M A , while is it elongated (albeit with moderate statistical significance) along the direction of the IMF during low M A . These findings are consistent with enhanced magnetic forces that prevail in the magnetosheath during low M A . The component of the magnetic forces parallel to the magnetopause produces the enhanced flows along and adjacent to the magnetopause, while the component normal to the magnetopause exerts an asymmetric pressure on the magnetopause that deforms it into an elongated shape.

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“…The effective interplanetary electric field (IEF) was calculated using the formula EKL = VxB Y zsin 2 (8/2) where 9 is the IMF clock angle [Kan and Lee, 1979]. This formula was initially derived by Sonnerup [1974] for the maximum rate of component merging in the subsolar region.…”

Section: Foundations For a New Directionmentioning

confidence: 99%