Microscale structure of the interplanetary medium and solar wind control of the time lags in the auroral zone geomagnetic response

Journal Article · Fri Mar 01 04:00:00 EST 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JA02246· OSTI ID:6159498

Hruska, A; Wilson, M D ^[1]

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1. National Research Council of Canada, Ottawa, Ontario (Canada)

While the level of auroral zone geomagnetic activity, as measured by the AE index, is determined by the value of the southward component, B{sub s}, of the interplanetary magnetic field (IMF), the delay in the geomagnetic response is modified by the microscale fluctuations of the IMF vector B. For extreme values of B{sub s}(B{sub s}> 5 nT and B{sub s} = 0) the geomagnetic disturbances associated with small values of {sigma}{sub z} last longer than those associated with large {sigma}{sub z}. Conversely, for other values of B{sub s}, the magnetosphere responds to the quasi-stationary interplanetary conditions with a shorter delay than to the time dependent solar wind conditions. Autocorrelations of the solar wind (SW), parameters evaluated for various time lags are always stronger when the initial value of {sigma}{sub z} is small than when it is large. Analysis of the autocorrelations and of the geomagnetic responses corresponding to them suggests that, for positive but not extremely large values of B{sub s}, the temporal fluctuations of B trigger the internal magnetospheric (or the SW-magnetospheric coupling) processes which increase the observed time lags in the auroral zone geomagnetic activity. The value of {sigma}{sub z} is the SW parameter indicating whether the magnetosphere responds to SW conditions almost immediately (within less than {approximately} 1 hour) or whether the magnetospheric response is more gradual and is delayed for another {approximately} 1 to {approximately} 4 hours. The data analyzed in this study indicate the existence of magnetospheric processes delaying the geomagnetic response to the SW conditions for B{sub s} = 0 but they do not allow us to draw conclusions on the effects of {sigma}{sub z} when B{sub s} is extremely high or equal to zero.

• OSTI ID: 6159498
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:A3; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
CORRELATIONS
DATA ANALYSIS
DOCUMENT TYPES
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
FLUCTUATIONS
FORECASTING
FUNCTIONS
INDEXES
INTERACTIONS
INTERPLANETARY MAGNETIC FIELDS
MAGNETIC FIELDS
RESPONSE FUNCTIONS
SOLAR ACTIVITY
SOLAR WIND
TIME DELAY
VARIATIONS