Astro Alert - MAJOR X-CLASS SOLAR FLARE ALERTS/MIDDLE LATITU

[Ulrich Rieth]

A s t r o A l e r t

Sun-Earth Alert

Solar Terrestrial Dispatch

http://www.spacew.com

28 May 2003

1. MAJOR X-CLASS SOLAR FLARE ALERTS

2. MIDDLE LATITUDE AURORAL ACTIVITY WATCH

MAJOR X-CLASS SOLAR FLARE ALERTS

Observers of the upcoming total annular solar eclipse (visit
www.skyandtelescope.com for details) will be interested to learn that a
significant and developing active sunspot complex has evolved over the last
several days into a potential power-house for solar flare activity.

Active sunspot Region 10365 is a rapidly developing/growing mass of
dense sunspots currently numbering in the neighborhood of 42. The sunspot
complex currently covers an area of approximately 1.2 billion square
kilometers. You could map more than twice the entire surface area of the
Earth into this spot complex. This region is also presently visible to the
unaided (but protected) eye. Remember never to look directly at the Sun
without appropriate eye protection.

Two powerful X-class solar flares were observed from this spot complex
within 1.5 hours of each other on the evening of 27 May EDT (late in the UTC
day of 27 May and early on 28 May). This activity was preceded on 26 May by
smaller M-class solar flares. Analysis of this activity has revealed that
most of these flare events were associated with coronal mass ejections (CMEs)
containing Earthward directed components.

Interestingly, there is evidence suggesting that perhaps only two of
these coronal mass ejections may actually survive the trip to the Earth. The
others may be "cannibalized" by the strongest and fastest coronal mass
ejections. Cannibalism in space occurs when one coronal mass ejection
travelling faster than another overtakes the slower one and cannibalizes it.
This process of cannibalization irreversibly changes the character of both of
the coronal mass ejection disturbances that are involved. Depending on the
nature of the CMEs, the end-product of the cannibalization may be a single
disturbance that is constructively reinforced to become stronger and more
volatile, or it may become a single disturbance that is weakened if the two
CMEs destructively merge together. In either case, the end-product is
invariably a CME that contains very little resemblance to the original CME.
For this reason, the Earth-bound impact of these types of space weather
disturbances are much more difficult to predict with accuracy.

Each of the smaller M-class flare associated CMEs have a good chance of
producing a single cannibalized CME. Similarly, the two X-class flares that
were observed also may have produced CMEs that have merged into a single
disturbance. Whether these disturbances have merged constructively or
destructively (assuming that they have in fact merged with other CMEs)
remains an open question.

What is known is that at least two separate and distinct space weather
CME disturbances are expected to impact the Earth over the coming days. The
first, associated with the smaller M-class flares, may impact the Earth on 29
May. The second and perhaps more energetic disturbance is expected to impact
the Earth early on 30 May (UTC time - which translates to the late evening
and early morning hours of 29/30 May, Eastern daylight time [EDT]).

Because these disturbances have the potential of being less predictable
and possibly more volatile than might normally be observed, there is at least
minor concern that their impact with the Earth may be stronger than would
normally be expected. For this reason, warnings are being issued to alert of
the potential for geomagnetic storm activity and auroral storm activity
("northern lights" activity) on 29 through perhaps 31 May inclusive, with
heaviest emphasis on 30 May. The official middle latitude aurora watch is
appended below and contains more details.

Additional major X-class solar flare activity is possible from active
sunspot Region 10365 over the coming days. There is also the potential for
energetic proton flares from this active region. Proton flares are nothing
more than solar flares that involve processes capable of accelerating protons
to near relativistic energies (>10 to 100 MeV) and velocities. These protons
enhance the radiation environment in space around the Earth and can pose a
hazard to satellite and (in less frequent cases) astronaut health, but are
not a health hazard to people living on the Earth. These energetic protons
also reac havoc with ionospheric-based radio communications systems by
producing a phenomenon known as polar cap absorption (PCA). PCA is intense
ionization of the polar ionosphere and can significantly alter the character
or strength of radio signals that propagate through these regions of the
ionosphere.

Region 10365 will remain in a sensitive position to throw other coronal
mass ejections toward the Earth during the next few days. It will rotate
behind the west limb of the Sun and will become incapable of significantly
affecting the Earth by this same time next week.

MIDDLE LATITUDE AURORAL ACTIVITY WATCH - 28-31 MAY 2003

VALID BEGINNING AT: EFFECTIVE IMMEDIATELY
VALID UNTIL: 23:00 UTC (7 pm EDT) ON 31 MAY

HIGH RISK PERIOD: 30 MAY (UTC DAYS)
MODERATE RISK PERIOD: 28 - 31 MAY

PREDICTED ACTIVITY INDICES: 30, 30, 35, 20 (28 MAY - 31 MAY)

POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: MODERATE - HIGH

POTENTIAL DURATION OF THIS ACTIVITY: MAIN BELT = 12 - 24 HOURS

MINOR BELT = 24 - 48 HOURS

ESTIMATED OPTIMUM OBSERVING CONDITIONS: NEAR LOCAL MIDNIGHT

EXPECTED LUNAR INTERFERENCE: NONE - LOW

OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: FAIR

AURORAL ACTIVITY *MAY* BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...

OREGON TO SOUTHERN IDAHO AND POSSIBLY NORTHERN UTAH TO WYOMING TO NORTHERN

NEBRASKA TO IOWA TO ILLINOIS TO INDIANA TO OHIO AND POSSIBLY NORTHERN

KENTUCKY AND NORTHERN WEST VIRGINIA TO MARYLAND.

ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...

IRELAND TO SOUTHERN UNITED KINGDOM AND POSSIBLY NORTHERN FRANCE TO BELGIUM

TO THE NETHERLANDS TO THE NORTHERN THIRD OF GERMANY TO NORTHERN POLAND TO

NORTHERN BELARUS TO NORTH-CENTRAL RUSSIA.

NEW ZEALAND AND SOUTHEASTERN TO SOUTH-CENTRAL REGIONS OF AUSTRALIA ALSO

HAVE A FAIR CHANCE TO OBSERVE PERIODS OF ACTIVITY.

SYNOPSIS...

A series of solar coronal mass ejections are expected to impact the
Earth over the next 72 hours. The first disturbance may impact on 29 May and
produce enhanced levels of activity. The most disturbed interval is expected
on 30 May when effects of what may be a more energetic coronal mass ejection
are expected to reach the Earth. This latter disturbance is associated with
two major X-class solar flares and has the potential for producing periods of
moderate to strong auroral activity over the high and middle latitude
regions. The intensity of the activity probably will not be particularly
significant. However, since the potential for cannibalistic CME activity is
fairly high (a faster CME overtaking a slower CME), the level of
predictability is reduced. There is a chance some regions of this disturbance
may involve strongly enhanced magnetic fields capable of coupling more
strongly with the Earth's magnetosphere to produce strong auroral storm
activity. There is also the possibility periods of activity may be fairly
weak. Because of these uncertainties and the complex space weather situation
which is evolving from this (and other ambient) activity, this watch is based
on an optimistic projection favoring a slightly stronger disturbance than
would otherwise be expected. The near-new phase of the moon, which will
contribute to optimally dark skies will also enhance the potential for
observing activity from middle latitudes, particularly on 30 May.

There is a strong potential for additional major solar flare activity
from active solar Region 10365. Future activity from this region may involve
additional Earthward-directed coronal mass ejection activity that could serve
to prolong the duration of favorable conditions for middle latitude sightings
of auroral activity.

This watch will remain valid through 23:00 UTC (7 pm EDT) on
31 May. It will then be updated or allowed to expire. For updated
information, visit: http://www.spacew.com/aurora/forum.html. For real-time
plots of current activity, visit: http://www.spacew.com/plots.html

PLEASE REPORT OBSERVATIONS OF AURORAL ACTIVITY TO:

http://www.spacew.com/submitsighting.html

NOTICE: THE NEXT HOME-STUDY INTERNET SPACE WEATHER FORECASTING COURSE

will commence on 16 June 2003. This course is suitable for anyone to

take (there are no prerequisites). It teaches you how to analyse solar

activity and predict space weather impacts of this activity on the Earth

and Earth-based technology systems (including predicting the occurrence

of auroral activity). It includes over 600 pages of printable curriculum

and may also optionally include several powerful software packages

developed for space weather studies and research.

Details are available at: http://www.spacew.com/www/course.html

The last offering of this course was October 2002. We do not know when

the next class may be offered. We encourage all who are interested to

consider enrolling soon.

** End of the AstroAlert Bulletin **

[Peter Kuklok]

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MAJOR SOLAR FLARE ALERT

ISSUED: 08:25 UTC, 28 MAY 2003

/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

SYNOPSIS:

Two X-class solar flares were observed recently from active Region
10365. The first was a class X1.4/2B and was observed at 23:07 UTC on 27 May.
The second X-class flare was a class X3.9/2B and occurred less than 1.5 hours
later at 00:27 UTC on 28 May. Both events were associated with moderate to
strong radio emissions, including Type II and IV sweeps. The Type II of the
first event was estimated to be approx. 600 km/sec (Palehua and Culgoora -
preliminary). The Type II of the second event is presently listed by SEC as
392 km/sec from Palehua. However, this second Type II is probably not
representative of the true shock velocity and probably should not be related
to the velocity of any associated coronal mass ejection activity.

SOHO was out of real-time contact shortly after the first X-class flare
(the last LASCO C2 image at 00:06 UTC confirmed the presence of what is
probably a full-halo CME. There is insufficient data to determine a reliable
velocity estimate from that single frame). The next contact with SOHO came at
05:18 UTC. A complex probable-full-halo ejecta pattern was visible in the
subsequent images. Plane of sky velocity estimates range from approximately
675 km/sec due north and south to approximately 850 km/sec toward the
southwest where the highest velocity ejecta appears to reside.

Although there is not yet any conclusive evidence from SOHO to say
whether the second X-class solar flare (which was roughly 4 times more
energetic than the first X-class flare) was associated with a full halo CME,
all evidence suggests one probably was. The jury will remain out on this
until the recorded SOHO data is played back and made available. We are
assuming, however, that a CME with at least equal or stronger strength to the
first CME was observed. We suggest there is a good possibility of a
cannibalistic CME scenario.

Two minor M-class flares on 26 May and early on 27 May (also from Region
10365). These two events also appear to have been associated with CMEs
containing Earthward-directed components. The second CME was notably faster
than the first and may overtake the first before reaching the Earth. Impact
with the Earth is likely sometime on 29 May (possibly late on 28 May).

The CME activity associated with the two X-class flares is predicted to
arrive sometime early on 30 May. Our impact assessment suggests a time
perhaps near 04:00 UTC on 30 May. A moderately strong shock front may
accompany this disturbance. There is a notable chance the heliospheric
current sheet may have been caught up within one of these CMEs from region
10365. We expect both northward and southward turnings of the IMF within
these disturbances, which may help fuel geomagnetic substorm activity. We
expect minor to major geomagnetic storming may be observed over the next
several days, but with heaviest emphasis for 30 May.

Energetic proton populations in the near Earth space environment at
energy levels greater than 10 MeV have been enhanced following the second
X-class solar flare. >10 MeV protons may reach or exceed event levels of 10
pfu over the next 12 hours. This may induce mild polar cap absorption
activity and may increase the incidence of spacecraft anomalies (SEU's, etc).

Region 10365 appears capable of producing additional significant
energetic activity over the next 24 to 72 hours. Major M and X-class flares
appear to remain distinctly possible. There is also a notable possibility for
an attendant major proton flare as well.

** End of Notice **

[Heiko]

a good possibility of a cannibalistic CME scenario .....