J-GLOBAL ID:200904063964682721  Research Project code:9950000046 Update date:Jan. 19, 2004

Mapping of electric field between 'GEOTAIL' and 'Akebono'

Study period:1997 - 2002
Organization (1):
Investigating Researcher (4):
Research overview:
It has been known that large-scale convection of plasma has been caused in the polar ionosphere. This convection has been regarded as caused by conduction of electric field in the solar wind to the ionospheric layer through the magnetosphere. Comprehensively, therefore, convection mapped as that within the ionospheric layer ought to be observed within magnetosphere. However, it is observed in the actual magnetospheric tail that electric field much larger than that corresponds to a large-scale convection is accompanied by a violent temporal variation. In this study, we took consideration on propagation of Alfven wave with a long period (above 10 minutes) and constructed a model in order to account for mechanism that slow temporal variation of global plasma convection propagates to the ionospheric layer. As the result, it was shown that high-frequency components of electric field variation in the far magnetosphere degraded in high altitudes and delay in propagation dependent on frequency took place. When the constructed model was applied to data concurrently measured with 'Akebono' and 'GEOTAIL' to compare, it was shown that this model well accounts for the actual data.
Keywords (7):
electric field ,  mapping ,  plasma ,  GEOTAIL ,  Akebono ,  magnetohydrodynamics ,  magnetic field freezing
Research program: Ordinary Research
Ministry with control over the research :
Ministry of Education, Culture, Sports, Science and Technology

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