To a special Solar Physics issue
on the Bastille Day Event:
Materials for the accompanying
CD-ROM
Multi-scale temporal features of the 14 July 2000 meter-wavelength
dynamic radio spectrum compared with TRACE data
by I.M. Chertok, V.V. Fomichev, A.A. Gnezdilov, R.V. Gorgutsa,
V.V. Grechnev, A.K. Markeev, R.W. Nightingale, and D.E. Sobolev
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Figure 1 (100 KB). SOHO/EIT (a) and LASCO/C2
(b) images show the region of the eruptive flare event of 14 July 2000
and related halo CME. The compressed inverted IZMIRAN dynamic radio spectrum
in 05:50-13:00 UT interval (c) and extracted time-intensity profiles (d)
at 58 MHz (right axis) and 86 MHz (left axis) display large-scale restructuring
of the noise storm associated with the event: sharp weakening of the pre-existing
noise storm in the 75-100 MHz range and some intensification of radio
emission at lower frequencies. This phenomenon was perhaps caused by interaction
of the halo CME with emitting coronal structures.
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Figure 2 (47 KB). Inverted TRACE images at
195 Å illustrating development of the EUV post-eruption arcade
with the well-organized loop, two-ribbon, and spine structures (see
the movie indicated below). Note that the exposures have been rescaled
to the same peak intensity to show the evolution of the bright elements.
The field of view is 230 by 170 Mm.
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Figure 3 (115 KB). Medium-scale dynamic
spectrum (a), 204 MHz metric (b) and 3000 MHz microwave (c) profiles
of the "Bastille Day" event. Several type II bands and slow-drifting decimetric
continuum are marked by indexes (aa)-(dd) and (ee), respectively. The frequency
drifts of the clearest bands correspond to the estimated shock wave speed
of 1100-2300 km/s that is comparable with the observed CME speed. Significant
broadband enhancements of the metric radio emission took place around of
10:24-10:27 UT coinciding with sharp development of the EUV arcade in the
north-east direction (see the movie indicated below). It appears
to correspond to the intensification of the electron acceleration
in a process of post-eruption loop formation.
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Figure 4 (75 KB). Enlarged dynamic
spectrum of the initial phase of the event with type II bands (aa)-(dd)
and some other fine-structure elements.
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Figure 5 (115 KB). Enlarged fragments
of the dynamic spectrum revealing the radio pulsations and type III-like
bursts. At the initial and maximum phases, these features have a time scale
of a few seconds which coincides with a typical time of formation and brightening
up of the loops in the EUV arcade. These the second-scale radio pulsations
appear to be related to the temporal fragmentation of the post-eruption
magnetic reconnection and particle acceleration processes. As for the longer
ten-second-scale pulsations predominating at the end of the flare event,
they may have been exited particularly by MHD oscillations of higher
and bigger coronal loop-like flux tubes, perhaps somehow related to the
CME.
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Movie: This composite movie allows to compare development of the
IZMIRAN metric-wavelenght dynamic spectrum and the EUV post-eruption arcade
observed with TRACE at 195 Å:
Javascript
movie (2.6 MB)
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