June 6 EVENT SUMMARY|
From Simon Plunkett (SOHO/LASCO)
LASCO and EIT observed a full halo CME today. The event was first visible
at all position angles in C2 at 15:54 UT. It appears as a bright front,
particularly over the N pole, with trailing filamentary material. The
plane-of-sky speed of the leading edge of the halo is about 908 km/s,
possibly with some deceleration in the outer part of the C3 field of view.
The halo is probably associated with an X2.3 flare and filament eruption
in AR 9026, located at about N21 E15. EIT observed the flare and filament
eruption beginning at about 15:12 UT. There was also an earlier X1.1 flare
and filament eruption from the same region, that was observed by EIT at
about 13:36 UT. This flare was probably associated with an earlier CME
that merged with the halo in C2.
Halo CME on 2000/06/07
LASCO and EIT observed a halo CME today, 2000/06/07. The event was
first visible as a faint diffuse front over the N and W limbs in C2 at
16:30 UT, and extended all around the occulter in the next image at 17:08
UT. There appears to be a second ring of enhanced brightness at 17:30 UT,
probably a second phase of the same event.
The CME was probably associated with an X1.2 flare in AR 9026, located
near central meridian at about N20 E02. This flare was observed by EIT at
15:36 UT. The plane-of-sky speed for the event was about 411 km/s at PA 180 (S pole).
Because this event was faint, it was difficult to identify a feature that could be
reliably tracked through a sufficient number of images to give a good speed measurement.
GEOPHYSICAL ACTIVITY FORECAST: The Geomagnetic field is expected to be mostly
quiet to unsettled for June 6 with possible isolated active periods.
Activity should increase to minor storming on June 7, due to the arrival
of the Earth-directed full-halo CME. Activity should increase on June 8
to major storm conditions, especially at higher latitudes.
From Mike Kaiser (WIND/WAVES)
I was surprised to see that the shock from the June 6 event arrived
cosiderably earlier than our predict based on Wind data (i.e. 800 km/sec
arriving after 19:30 June 8), but pretty good compared to the alternate
version of the Cassini data (1300 km/sec). There is an
obvious light travel time difference of some 22 or 23 minutes due to the
fact that Cassini is nearly 4 AU from the sun. Clearly, Cassini
does not see much of the Wind 'main' event only the bright blob.
If you look carefully at the WAVES data,
you can see that this event consists of more than just the two blips at
2 and 4 MHz. Hidden somewhat by the intense type III bursts one can see
that these blips are a continuation of something that started at about
15:24 or so. The speed fit to these also matches 1200-1300 km/sec with
a liftoff of about 15:05 to 15:10. I suspect it must be this 'ignored'
component that reach Earth with an overall transit speed of ~1000 km/sec.
From Mike Desch (WIND/WAVES)
The Cassini data from June 7
show an interplanetary type II drifting between 20 and 10 kHz. This is
probably due to an earlier CME on the west limb - or possibly from the NW
limb/backside CME of June 4 (06:36) because it would be clearly visible to
Cassini on the other side of the Sun to the Earth. This would also make sense
in terns of the propagation time out into the interplanetary medium where the
densities are a few/cm^3
From Harlan Spence (POLAR/CEPPAD)
During the course of 06/07/00, the entire magnetosphere was bathed by
solar energetic particles (SEP). This non-thermal population is created in
association with strong shock waves travelling through the inner heliosphere
as a result of fast CMEs. They race ahead of the shock and arrive first.
The SEP fluxes started to increase on the 7th and have continued to rise
even through the morning of the 8th.
The ACE spacecraft is sitting at L1 monitoring the solar wind ~200 Re
upstream of the Earth. Just hours ago, the first shock (there may be more
to come as this seemed to be a compound solar event) was encountered. The
solar wind speed jumped discontinuously by nearly a factor of two (to >800
km/sec). The density jumped to >10/cc, temperature to >10^6K, and the
magnetic field magnitude to >20 nT. At the leading edge of the shock, the
IMF was nearly purely southward (-Bz), the orientation which leads to
optimal coupling of all that flow energy into the magnetosphere. The IMF
has remained southward for nearly the past four hours with an average Bz
value of <-10 nT. In the last hour, the post-shock IMF seems to be
intensifying with amplitudes approaching 30 nT and almost purely Bz south.
The post-shock energetic particle population is impressively high; the MeV
protons have risen nearly two orders of magnitude from pre-event background.
While measures of geomagnetic activity usually take some time to process,
predictive models give some idea of what is going on instantaneously from
other real-time data sources (such as ACE). NOAA/SEC is estimating high
world-wide ground magnetic activity with "Kp" indices of 6-7 (on a quasi-log
scale of 0-9) for the last three hours (which now puts us in the "red"
zone). Our best visibility into storm activity (Kyoto University's
real-time Dst index) stopped updating at 0UT today, so we don't have a good
feel yet for the size of storm that is likely brewing. However, a quick
look at individual ground magnetometer station data shows that impressive
electrical currents started flowing around 9UT today, consistent with the
propagation time of the shock from L1.
From Daniel Berdichevsky
There have been highly disturbed solar wind conditions near Earth since
approximately 0900 UT (06/08/00).
ACE-NRT SWEPAM and MAG instrument plasma sensors indicate the passing of a
strong IP shock at approx. 0845UT, June 8, 2000. After the IP shock the
interplanetary magnetic field (IMF) turned south. Currently, 1330 UT, June 8,
the IP solar wind conditions are as follow: IMF intensity: above 20 nT. IMF
Z-component fluctuates and now is South. IMF azimuth is mainly in the
Y-direction. Solar wind (protons) speed above 700 km/s, density above 10 part/cc
temperature about 300 000 Deg Kelvin, it was a millon degrees for a few hours
after passage of the shock. Spike in ACE-NRT SIS >10 MeV but not in >30 MeV
channel at the time of the IP shock. Also spike near IP shock in ions at lower
energies (ACE-NRT EPAM).
Today there were several compressions of the magnetosphere as they are sensed
at geostationary orbit with the Hp component of the magnetic field. These are
measures by the enviromental satellites GOES.
Around the time of the arrival at Earth of the
IP shock the NOAA estimated global geomagnetic Kp-index jumped to 7
(a log scale from 0 to 9). Geostationary GOES 8 Hp magnetic
field component shows extreme compression values near 1300 UT, June 8 (Today),
(GOES 8 at Long. W 75).