[LeArc] [Fwd: AstroAlert: Impact of Coronal Mass Ejection - Aurora Warning]
Jay Hainline
[email protected]
Wed, 27 Nov 2002 01:11:11 +0000
-------- Original Message --------
Subject: AstroAlert: Impact of Coronal Mass Ejection - Aurora Warning
Date: Tue, 26 Nov 2002 15:19:01 -0700 (MST)
From: Cary Oler <[email protected]>
To: [email protected]
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This Is SKY & TELESCOPE's AstroAlert for Sun-Earth Interactions
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A s t r o A l e r t
Sun-Earth Alert
Solar Terrestrial Dispatch
http://www.spacew.com
26 November 2002
Contents
MIDDLE LATITUDE AURORAL ACTIVITY WARNING
MIDDLE LATITUDE AURORAL ACTIVITY WARNING
A shock front in the solar wind, similar in properties to a bomb
explosion blast wave that occurs on the Earth, has been observed by the ACE
spacecraft at 21:10 UTC (4:10 pm EST) on 26 November. The shock front is the
result of the explosive eruption of a large solar filament (a huge area of
gas suspended above the surface of the Sun's photosphere by strong magnetic
fields) that was observed on 24 November. The eruption produced a full halo
coronal mass ejection which is now impacting the Earth.
Very early, initial and preliminary data from the ACE spacecraft is
showing a strong interplanetary magnetic field that is oriented in a
direction favorable for producing auroral storm activity. As a result, a
middle latitude auroral activity warning has been issued. Periods of minor to
major geomagnetic and auroral storming will be possible with this
disturbance, particularly if the interplanetary magnetic field maintains its
favorable southward orientation.
You can determine whether conditions might be favorable for producing
periods of auroral storming yourself by visiting our plots page at:
http://www.spacew.com/plots.html. Perhaps the most important plot to watch is
the Bz plot, which describes the strength of the north-south component of the
interplanetary magnetic field (IMF). When the Bz plot is sustained in a
strong negative (southward) orientation (greater than -10 to -15 nT for
longer than an hour or two), geomagnetic and auroral storming is likely to
commence. Stronger solar wind velocities and densities also play a role in
modulating the response of the Earth's magnetosphere, but the dominant
parameter is the north-south Bz component of the IMF. Plots at the above URL
are updated every 1 to 2 minutes with real-time data.
European and North American observers may be well placed for observing
the strongest phase of activity. The middle latitude auroral activity warning
is included below.
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
MIDDLE LATITUDE AURORAL ACTIVITY WARNING
ISSUED: 22:10 UTC, 26 NOVEMBER 2002
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
*** POTENTIAL FOR MODERATE TO HIGH ACTIVITY EXISTS ***
For North Americans, begin watching TONIGHT.
VALID BEGINNING AT: EFFECTIVE IMMEDIATELY
VALID UNTIL: 22:00 UTC (5 PM EST) ON 27 NOVEMBER
HIGH RISK PERIOD: 27 NOVEMBER (UTC DAYS)
MODERATE RISK PERIOD: 26 - 28 NOVEMBER
PREDICTED ACTIVITY INDICES: 16, 40, 15, 12 (26 NOV - 29 NOV)
POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: MODERATE TO HIGH
POTENTIAL DURATION OF THIS ACTIVITY: MAIN BELT = 12 TO 18 HOURS
MINOR BELT = 18 TO 24 HOURS
ESTIMATED OPTIMUM OBSERVING CONDITIONS: PRIOR TO AND NEAR LOCAL MIDNIGHT
EXPECTED LUNAR INTERFERENCE: MODERATE
OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: FAIR TO GOOD
AURORAL ACTIVITY *MAY* BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...
OREGON TO EXTREME NORTHERN UTAH TO WYOMING TO NORTHERN NEBRASKA TO IOWA TO
ILLINOIS TO INDIANA TO OHIO TO WEST VIRGINIA TO NORTHERN VIRGINIA AND
MARYLAND.
ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...
NORTHERN FRANCE TO BELGIUM TO CENTRAL GERMANY TO CENTRAL POLAND TO
NORTHERN BELARUS TO NORTH-CENTRAL RUSSIA. ACTIVITY MAY ALSO BE OBSERVED
FROM NEW ZEALAND AND SOUTHEASTERN AUSTRALIA.
SYNOPSIS...
A moderately strong interplanetary disturbance is in-progress. Impact
of the disturbance occurred at the Earth near 21:52 UTC (4:52 pm EST).
Periods of minor to major auroral storming are expected to accompany this
disturbance. Observations of auroral activity will be possible across
wide-spread middle latitude regions during the next 12 to 18 hours. Initial
data suggest the disturbance could become fairly strong initially.
This warning will remain in effect until 22:00 UTC on 27 November. It
will then be downgraded to a watch or allowed to expire.
PLEASE REPORT OBSERVATIONS OF AURORAL ACTIVITY TO:
http://www.spacew.com/submitsighting.html
CURRENT REPORTED SIGHTINGS OF ACTIVITY MAY BE FOUND AT:
http://www.spacew.com/www/auroras.html
CURRENT REAL-TIME CONDITIONS (PLOTS) ARE AVAILABLE AT:
http://www.spacew.com/plots.html
CURRENT GALLERY OF ASTRONOMICAL AND AURORA IMAGES:
http://www.spacew.com/gallery
DISCUSSIONS OF ACTIVITY
http://www.spacew.com/aurora/forum.html
** End of the AstroAlert Bulletin **
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