Identification

Title

Dayside magnetospheric and ionospheric responses to a foreshock transient on 25 June 2008: 2. 2-D evolution based on dayside auroral imaging

Abstract

The foreshock region involves localized and transient structures such as foreshock cavities and hot flow anomalies due to solar wind-bow shock interactions, and foreshock transients have been shown to lead to magnetospheric and ionospheric responses. In this paper, the interaction between a foreshock transient and the magnetosphere-ionosphere system is investigated using dayside aurora imagers revealing structures and propagation in greater detail than previously possible. A foreshock transient was detected by Time History of Events and Macroscale Interactions during Substorms B and C during 1535-1545 UT on 25 June 2008. Time History of Events and Macroscale Interactions during Substorms A, D, and E observed magnetopause compression, cold plasma enhancement, and ultralow frequency waves in the dayside magnetosphere. The all-sky imager at South Pole observed that both diffuse and discrete aurora brightened locally soon after the appearance of this foreshock transient. The diffuse aurora brightening, which corresponded to a region a few Re size in geocentric solar magnetospheric Y in the equatorial plane, propagated duskward with an average speed of similar to 100km/s. Soon after the diffuse aurora brightened, discrete aurora also brightened and extended duskward, which was consistent with the motion of the foreshock transient as it swept through the magnetosheath while impacting the magnetopause. Equivalent horizontal currents measured by magnetometers revealed a pair of field-aligned currents moving duskward consistent with motion of the discrete aurora patterns. We conclude that the high-resolution and two-dimensional observation of auroral responses by ground-based all-sky imager can help to estimate the evolution and propagation of upstream foreshock transients and their substantial impacts on the magnetosphere-ionosphere coupling system, including magnetospheric compression and currents in the ionosphere.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7r2149q

codeSpace

Dataset language

eng

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geoscientificInformation

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Text

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title

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reference date

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publication

effective date

2016-01-01T00:00:00Z

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publication

effective date

2018-08-01T00:00:00Z

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None

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contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

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pointOfContact

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